A Pest Management Strategic Plan for Production in

Douglass E. Stevenson, Ph.D. Extension Associate - Agricultural & Environmental Safety Texas Cooperative Extension, Texas A&M University System

Mark A. Matocha Extension Program Specialist - Agricultural & Environmental Safety Texas Cooperative Extension, Texas A&M University System Table of Contents

Page Table of Contents ...... i List of Figures ...... vii List of Tables ...... viii Executive Summary ...... 1 Research priorities...... 1 Regulatory priorities...... 2 Educational priorities ...... 3 Introduction ...... 4 Stakeholder recommendations ...... 4 Philosophy...... 4 Production facts...... 4 Production regions ...... 4 East Texas...... 5 The Blacklands ...... 6 South Texas...... 6 Lower Rio Grande Valley ...... 7 High Plains...... 7 Rolling Plains ...... 8 Trans-Pecos ...... 8 Irrigated production ...... 8 Dryland production ...... 9 Cotton production in Eastern, Southern and Blacklands regions ...... 10 Cotton production in the Lower Rio Grande Valley ...... 10 Full-season production ...... 10 Bt transgenic cotton...... 11 Early stalk destruction and field cleanup ...... 12 Stalk destruction laws ...... 12 and Pest Management...... 13 Early-season pests ...... 14 Stand destroying pests ...... 15 Thrips ...... 15 Cutworms ...... 17 Aphids ...... 18 Grasshoppers ...... 19 Whiteflies ...... 20 Saltmarsh caterpillar (Estigmine acrea) ...... 21 Other early-season foliage-feeding pests ...... 21 Early-season square-destroying pests ...... 21 Cotton fleahopper (Pseudatomoscelis seriatus) ...... 22 Boll weevil (Anthonomus grandis) ...... 22 Boll weevil eradication ...... 24 Overwintered boll weevil management strategy ...... 25 Lower Rio Grande Valley ...... 25 Eastern, Southern and Blacklands...... 26 Boll weevil trap index ...... 27 High Plains, Rolling Plains and Trans-Pecos ...... 27 Early-season plant bugs (Lygus and Creontiades spp.)...... 28 Lygus bugs ...... 28 Eastern, Southern and Blacklands ...... 28 High Plains Rolling Plains and Trans-Pecos ...... 29 Creontiades spp. Lower Rio Grande Valley ...... 29

i Page Early-season stink bugs ...... 30 Eastern, Southern and Blacklands...... 30 High Plains, Rolling Plains and Trans-Pecos ...... 30 Mid-season and Late-season pests...... 31 Cotton bollworm and tobacco budworm...... 31 Bollworm and budworm management in Bt transgenic cotton ...... 34 Mid-season and Late-season boll weevil management strategy ...... 34 Lower Rio Grande Valley ...... 35 Eastern, Southern and Blacklands...... 35 High Plains, Rolling Plains and Trans-Pecos ...... 36 Pink bollworm ...... 36 Pink bollworm management in conventional cotton ...... 37 Pink bollworm management in Bt transgenic cotton...... 38 The pesticide option ...... 38 The non-pesticide option ...... 38 The eradication option ...... 39 Pink bollworm eradication ...... 39 Eradication in the Trans-Pecos and Phase I area ...... 41 Eradication in the High Plains and Phase II area ...... 42 Mid-season and Late-season plant bugs and stink bugs ...... 42 Mid-season Lygus bugs ...... 43 Eastern, Southern and Blacklands ...... 43 High Plains, Rolling Plains and Trans-Pecos ...... 43 Creontiades spp. Lower Rio Grande Valley ...... 44 Mid- and Late-season stink bugs...... 45 Eastern, Southern and Blacklands...... 45 High Plains, Rolling Plains and Trans-Pecos ...... 45 Lower Rio Grande Valley ...... 45 Beet armyworm ...... 45 Lower Rio Grande Valley ...... 45 Eastern, Southern and Blacklands...... 46 High Plains, Rolling Plains and Trans-Pecos ...... 46 Cabbage looper and other loopers (: Geometridae) ...... 47 Lower Rio Grande Valley ...... 48 Eastern, Southern and Blacklands...... 48 High Plains, Rolling Plains and Trans-Pecos ...... 48 Spider mites (Acari: Tetranychidae)...... 48 Other mid- and late-season pests ...... 49 ...... 50 Avermectin (Abamectin®®, Zephyr ) ...... 50 Acephate (Orthene®®, Address )...... 50 Acetamprid (Intruder®)...... 51 Aldicarb (Temik®)...... 51 Amitraz (Ovasyn®) ...... 51 Azinphos-methyl (Guthion®)...... 51 Bifenthrin (Capture®) ...... 52 Carbofuran (Furadan®) ...... 52 Chlorpyrifos (Lorsban®®, Lock-on ) ...... 52 Cyfluthrin (Baythroid®) ...... 52 Cypermethrin (Ammo®® 2.5EC and Ammo WSB) ...... 53 Deltamethrin (Decis®) ...... 53 Dicofol (Kelthane®) ...... 54 Dicrotophos (Bidrin®) ...... 54 Dimethoate (Cygon®®, De-Fend , Dimate®)...... 55 Disulfoton (Di-Syston®) ...... 55

ii Page Emamectin benzoate (Denim®®, Proclaim ) ...... 55 Endosulfan (Thiodan®®, Phaser ) ...... 55 Esfenvalerate (Asana®) ...... 56 Fenpropatrhin (Danitol®) ...... 56 Gossyplure (Checkmate PBW®®, No Mate PBW , PB Rope L®) ...... 56 Imidacloprid (Gaucho Grande®®, Leverage , Provado®, Trimax®) ...... 57 Indoxacarb (Steward®)...... 57 Lambda-Cyhalothrin (Karate®®, Warrior ) ...... 58 Malathion (Fyfanon®) ...... 58 Methamidophos (Monitor®) ...... 58 Methomyl (Lannate®) ...... 58 Methoxyfenozide (Intrepid®)...... 59 Methyl parathion (Methyl Parathion, Penncap-M®) ...... 59 Oxamyl (Vydate®) ...... 59 Phorate (Thimet®) ...... 60 Profenofos (Curacron®) ...... 60 Propargite (Comite®) ...... 60 Pyriproxyfen (Knack®) ...... 61 Spinosad (Tracer®) ...... 61 Tebufenozide (Confirm®) ...... 61 Thiamethoxam (Centric®®, Cruiser ) ...... 61 Thiodicarb (Larvin®)...... 62 Tralomethrin (Scout X-tra®) ...... 62 Zeta-Cypermethrin (Fury®®, Mustang Max ) ...... 62 Weed Control ...... 63 Herbicides...... 65 Herbicides applied post-harvest or pre-plant to control winter weeds ...... 65 Glyphosate (Roundup®) ...... 65 Oxyfluorfen (Goal®) ...... 65 2,4-D (Formula 44®®,Weedone , Weedar®) ...... 65 Prometryn (Caparol®®, Cotton Pro , Prometryne®) ...... 65

Pre-plant herbicides applied to control emerged weeds ...... 65 Glyphosate (Roundup®) ...... 65 MSMA ...... 65 Paraquat (Gramoxone®)...... 65 Thifensulfuron + Tribenuron (Harmony Extra®) ...... 65 2,4-D (Formula 44®®,Weedone , Weedar®) ...... 65 Glufosinate (Ignite®)...... 65

Pre-plant incorporated (PPI) herbicides ...... 66 Norflurazon (Zorial Rapid®) ...... 66 Pendimethalin (Prowl®®, Prowl H2O, Pendimax®) ...... 66 Trifluralin (Treflan®®, Trilan ) ...... 66

Pre-plant incorporated (PPI) / preemergence (PRE) herbicides ...... 66 Norflurazon (Zorial Rapid®) ...... 66 Trifluralin (Treflan®®, Trilan ) ...... 66 Pendimethalin (Prowl®®, Prowl H2O , Pendimax®) ...... 66

preemergence herbicides ...... 66 Diuron (Karmex®®, Direx ) ...... 66 Fluometuron (Cotoran®) ...... 66 S-Metolachlor (Dual Magnum®®, Dual II Magnum , Cinch®) ...... 66 Norflurazon (Zorial Rapid®) ...... 66

iii Page Prometryn (Caparol®®, Cotton Pro , Prometryne®) ...... 66 Pyrithiobac (Staple®) ...... 66 Clomazone (Command®) ...... 67 Postemergence (POST) or post-directed (PDIR) herbicides ...... 67 Trifluralin (Treflan®®, Trilan ) ...... 67 Pendimethalin (Prowl®®, Prowl H2O , Pendimax®) ...... 67 S-Metolachlor (Dual Magnum®®, Dual II Magnum , Cinch®) ...... 67 Prometryn (Caparol®®, Cotton Pro , Prometryne®) ...... 67 Fluometuron (Cotoran®) ...... 67 Diuron (Karmex®®, Direx ) ...... 67 Lactofen (Cobra®) ...... 67 DSMA ...... 67 MSMA ...... 67 Pyrithiobac (Staple®) ...... 67 Fluazifop (Fusilade DX®) ...... 67 Fluazifop + Fenoxaprop (Fusion®) ...... 68 Clethodim (Select®) ...... 68 Quizalofop (Assure II®)...... 68 Sethoxydim (Poast Plus®) ...... 68 Carfentrazone (Aim®)...... 68 Pyraflufen-ethyl (ET®) ...... 68 Flumioxazin (Valor®)...... 68 Linuron + Diuron (Layby-Pro®) ...... 68 Oxyfluorfen ...... 68 Glyphosate...... 68 Glufosinate (Ignite®)...... 68 Bromoxynil (Buctril®) ...... 68 Trifloxysulfuron (Envoke®) ...... 68

Herbicides applied at layby ...... 69 Prometryn (Caparol®®, Cotton Pro , Prometryne®) ...... 69 Linuron + Diuron (Layby-Pro®) ...... 69 Diuron (Karmex®®, Direx ) ...... 69 Fluometuron (Cotoran®) ...... 69 MSMA ...... 69 Pyrithiobac (Staple®) ...... 69 Carfentrazone (Aim®)...... 69 Pyraflufen-ethyl (ET®) ...... 69 Flumioxazin (Valor®)...... 69 Glyphosate...... 69

Cotton Disease Control...... 70 Seedling diseases ...... 70 Rhizoctonia ...... 70 Pythium ...... 70 Fusarium ...... 70 Thielaviopsis ...... 71 Seedling disease reduction practices ...... 71 Root and vascular diseases...... 72 Bronze wilt ...... 72 Causal agent and disease development ...... 73 Symptoms ...... 73 Distinguishing bronze wilt from other diseases ...... 74 Genetic predisposition to bronze wilt – "B genes" ...... 74 Prevention and control ...... 75

iv Page Cotton root rot ...... 75 Causal agent and disease development ...... 75 Symptoms ...... 76 Prevention and control ...... 77 Cultural control ...... 77 Chemical control ...... 78 Vascular wilt diseases ...... 78 Fusarium wilt ...... 78 Causal agent and disease development ...... 79 Symptoms ...... 79 Prevention and control ...... 79 Verticillium wilt ...... 79 Causal agent and disease development ...... 79 Symptoms ...... 79 Prevention and control ...... 79 Foliar diseases ...... 80 Ascochyta (wet weather) blight ...... 80 Symptoms ...... 80 Prevention and control ...... 80 Bacterial blight ...... 80 Symptoms ...... 80 Bacterial blight resistance...... 81 Prevention and control ...... 81 Cultural control ...... 81 Chemical control ...... 82 Boll rot ...... 82 Cotton leaf rust ...... 82 Causal agent and disease development ...... 82 Symptoms ...... 82 Prevention and control ...... 83 Chemical control...... 83 Other foliar diseases and minor leaf spots ...... 83 Fungicides ...... 84 Azoxystrobin (Protégé®®, Quadris )...... 84 Bacillus subtilis (Kodiak®®, Kodiak HB ) ...... 84 Captan (Captan®®, Orthocide ) ...... 84 Carboxin (Vitavax®) ...... 84 Chloroneb (Nu-Flow D®®, Demosan ) ...... 84 Etridiazole (Ethazol®®, Terrazole ETMT) ...... 84 Fludioxonil (Maxim®) ...... 84 Iprodione (Rovral®) ...... 85 Mancozeb (Dithane M-45®®, Manzate D ) ...... 85 Mefanoxam (Apron XL®®, Ridomil Gold ) ...... 85 Metalaxyl (Apron®®, Ridomil , Allegiance®) ...... 85 Myclobutanil (Nu-Flow M®)...... 85 Pentachloronitrolbenzene (Terrachlor®, PCNB) ...... 85 TCMTB (Argent®®, Ascend , Nusan®, Nu-Flow T®) ...... 86 Thiram...... 86 Triadimenol (Baytan®) ...... 86 Trichoderma harzianum (T-22 Planter Box®®, T-22G , F-Stop®) ...... 86 Nematodes ...... 87 Root-knot nematode ...... 87 Causal agent and disease development ...... 87 Symptoms ...... 87 Prevention and control ...... 87

v Page Resistant cotton varieties ...... 87 Chemical control...... 88 Other nematodes...... 88 Nematicides and soil fumigants...... 89 1,3-Dichloropropene (Telone II®, 1,3-D) ...... 89 Chloropicrin + 1,3-D (Telone®® C-17, Telone C-35) ...... 89 Aldicarb (Temik®)...... 89 Fenamiphos (Nemacur®) ...... 90 Metam-sodium (Vapam®®, Nemasol )...... 90 Worker Activities ...... 91 Scouting ...... 91 Manual weed control ...... 91 Irrigation ...... 91 Conclusions ...... 92 Education ...... 92 Regulatory...... 92 Research...... 93 Advisory Committee Members ...... 95 Acknowledgments...... 95 References ...... 96 Efficacy Tables ...... 98 Herbicide Efficacy Tables ...... 108 Cotton Harvest Aid Chemicals and Plant Growth Regulator Efficacy Tables ...... 112 Fungicide and Nematicide Efficacy Tables ...... 114 Arthropod Pest Species Index...... 116 Arthropod Common Name Index...... 117 Pesticide Index ...... 118

vi List of Figures

Figure Page Fig. 1. Texas vegetational regions ...... 5 Fig. 2. Boll weevil in the U.S. (1892-1966) ...... 23 Fig. 3. Boll weevil eradication program (2004) ...... 25 Fig. 4. Pink bollworm eradication plan...... 40

vii List of Tables

Table Page Table 1. Boll weevil trap index...... 27 Table 2. Seed treatment insecticides ...... 98 Table 3. Insecticides applied in-furrow at planting for thrips (Frankliniella spp. and Thrips spp.) ...... 98 Table 4. Insecticides applied to foliage for thrips (Frankliniella spp. and Thrips spp.) . . . . 99 Table 5. Insecticides for cotton fleahopper (Pseudatomoscelis seriatus) ...... 99 Table 6. Insecticides for overwintering boll weevil (Anthonomis grandis) ...... 99 Table 7. Insecticides for grasshoppers (Brachystola magna and Melanoplus spp.) . . . . 100 Table 8. Insecticides for beet armyworm (Spodoptera exigua) and other armyworms . . 100 Table 9. Insecticides for saltmarsh caterpillar (Estigmene acrea) ...... 101 Table 10. Insecticides for Lygus bugs (Lygus spp.) ...... 101 Table 11. Ovicides for cotton bollworm (Helicoverpa zea) and tobacco budworm (Heliothis virescens) eggs ...... 102 Table 12. Microbial insecticides for bollworm/budworm (H. zea/H. virescens) larvae ...... 102 Table 13. Insecticides for bollworm (Helicoverpa zea) larvae ...... 102 Table 14. Insecticides for tobacco budworm (Heliothis virescens) larvae ...... 103 Table 15. Insecticides for in-season boll weevil (Anthonomis grandis) ...... 103 Table 16. Insecticides for aphids in cotton (Aphis gossyppii, A. craccivora and Myzus persicae) ...... 104 Table 17. Insecticides for stink bugs ...... 104 Table 18. Insecticides for pink bollworm (Pectinophora gossyppiella)...... 105 Table 19. Insecticides for cabbage looper (Trichoplusia ni) and other loopers ...... 105 Table 20. Acaricides / Insecticides for spider mites (Acari: Tetranychidae) ...... 105 Table 21. Insecticides for silverleaf whitefly (Bemisia argentifolii) and other whiteflies . . 106 Table 22. Insecticides for Cutworms (Rio Grande Valley) ...... 106 Table 23. Insecticides for plant bugs (Creontiades spp.) (Rio Grande Valley) ...... 107 Table 24. Herbicides applied post-harvest or pre-plant to control winter weeds ...... 108 Table 25. Preplant herbicides applied to control emerged weeds ...... 108 Table 26. Preplant incorporated (PPI) herbicides ...... 109 Table 27. Preplant incorporated / preemergence herbicides ...... 109 Table 28. Preemergence herbicides ...... 109 Table 29. Postemergence or Post-directed herbicides ...... 110 Table 30. Herbicides applied at layby ...... 111 Table 31. Herbicides and plant growth regulators (PGRs) applied as harvest aids and weed control agents at boll opening and at harvest of cotton ...... 112 Table 32. Miscellaneous plant growth regulators applied to cotton during the growing season to regulate the growth and fruiting process ...... 113 Table 33. Fungicides for cotton seed treatment or in-furrow application at planting ...... 114 Table 34. Fungicides for cotton foliar diseases ...... 115 Table 35. Soil fumigants and nematicides for nematode control in cotton ...... 115

viii Executive Summary

Research Priorities

In the coming years cotton pest management research will be vital to the Texas agricultural economy. Research must continue with both basic and applied research. It is imperative to maintain level or increased support of public research institutions, including the Land Grant College system, the Experiment Station system and Texas Cooperative Extension, which together focus exclusively on the needs of Texas producers and not on broader national marketing imperatives. Cotton pest management research must continue with both basic and applied research in the various aspects of cotton production, including, agronomy, genetics, physiology, weed control, plant diseases and . Agronomic research must include investigations into weed physiology, herbicide resistance, ecological shifts in weed populations under selection by single herbicides or herbicide classes, continued breeding of conventional varieties, while searching for desirable traits for use in transgenic varieties. Insect pest management research must continue evaluation of crop protection technology while also addressing changes in cotton ecosystems resulting from the use of transgenic cotton varieties and the effects following eradication of boll weevil and pink bollworm. Plant disease research must continue to investigate sources of disease resistance, production practices to reduce incidence of several diseases not controlled by fungicides, and the periodic evaluation of crop protection fungicides. It is also essential to develop risk mitigation measures to reduce human and environmental exposure to pesticides.

! Evaluate economics of conventional vs. transgenic weed control systems

! Evaluate the potential for and/or extent of increased weed resistance/shifts as a result of single herbicide use over multiple years

! Develop programs for potential weed resistance management

! Evaluate the efficacy and value of in-season plant growth regulators (PGRs)

! Evaluate the efficacy and value of end of season PGRs and defoliants

! Identify and evaluate tools for managing cotton root rot

! Amplify research on pests that transgenic crops do not control such as plant bugs and stink bugs

! Examine and re-examine economic thresholds and sub-threshold infestation levels for insect pests under various production systems

! Identify desirable transgenic traits for commercial research and development

! Evaluate seed treatment chemicals and coated seed technology to reduce costs and optimize profitability

! Investigate sources of resistance to bacterial blight

! Protect and expand the positions of Extension Agents-IPM and District Specialists to conduct research on cotton pest management.

1 Regulatory Priorities

Regulatory priorities focused almost exclusively on pesticides. At the top of the list were priorities surrounding the regulation of transgenic cotton varieties. The importance of transgenic cotton in the control key lepidopterous pests means that producer organizations, industry and the three major groups of the land-grant college system must come together to address the regulatory process to preserve this technology and reduce or eliminate the associated technology fees. Other priorities centered on preservation and continued registration of pesticides vital to cotton production. These included several old organophosphate insecticides, such as ULV malathion, which is essential to boll weevil eradication, and dicrotophos, a key insecticide in the control of plant bugs, aphids and several other pests not controlled by transgenic Bt cotton varieties. Priorities also included the continued registration of 2,4-D as a tool for post-harvest crop destruction and the preservation of all herbicides presently registered on cotton for resistance management arising from widespread use of transgenic herbicide tolerant varieties. Priorities also included the preservation and support of reregistration of seed treatment chemicals.

! Address grower concerns over rising technology fees for transgenic varieties as well as future availability of conventional varieties

! Maintain registrations of other herbicides for resistance management in view of widespread use of herbicide-tolerant varieties

! Alleviate current high costs of registration and re-registration of limited acreage herbicides that remain valuable to producers

! Maintain registration of 2,4-D as invaluable tool for crop destruction, volunteer, and pre-plant weed control

! Evaluate the impact of online pesticide sales on geographical sales reporting

! Maintain registrations of older insecticides such as dicrotophos in spite of decreasing use

! Preserve insecticides necessary to eradicate boll weevil and pink bollworm from affected areas of Texas

! Maintain availability of seed treatment chemicals

2 Educational Priorities

Educational priorities fell into five categories. First, were priorities for continued educational programs on pesticide use, safety, drift management and application methods. Second, was continued development of educational programs for weed management, identification of herbicide injury, and symptoms of herbicide carryover, herbicide resistance management, identification of herbicide resistance, and the identification of environmental effects that have been misidentified as herbicide resistance. Third, were priorities for insect pest management educational programs on beneficial and pest insect identification, education programs for field scouts and continuing the TPMA/EA-IPM coordinated cotton pest scouting program. Fourth, education priorities included the preservation and expansion of the positions of Extension Agents-IPM and District Specialists as local resources for cotton producers. It included producer input and cooperation to provide direction and goals for Extension Agents-IPM and District Specialists to develop education programs. Finally, a set of general educational priorities were established, which included web-based educational resources, publishing success stories and stakeholder support for extension positions in county and district positions, and improving the information network among county, district, and state research and extension personnel.

! Educate growers and applicators on proper sprayer calibration and cleanout procedures

! Educate growers and applicators on drift management

! Educate growers on proper identification of herbicide misapplication and environmental effects that have been misidentified as herbicide resistance

! Emphasize importance of residual herbicides for managing weed resistance/shifts in herbicide-tolerant varieties

! Educate growers and scouts on proper scouting methods for stink bugs

! Preserve and expand the positions of Extension Agents-IPM and District Specialists as local resources for cotton producers

! Preserve and develop producer input and cooperation to provide direction and goals for Extension Agents-IPM and District Specialists to develop education programs

! Develop web-based educational resources for county producers and other significant interest groups

! Publish success stories and stakeholder support for extension positions in county and district positions

! Improve information network among county, district, and state research and extension personnel

3 Introduction

The safety standards established by the 1996 Food Quality Protection Act (FQPA) will potentially impact certain crop protection tools used by cotton producers in Texas. The United States Department of Agriculture (USDA) has requested that producers of all commodities cooperate with research scientists and educators from the Land Grant University system, regulatory officials, and professional crop advisors (PCAs) to develop Pest Management Strategic Plans (PMSPs) that identify research, regulatory, and educational pest management priorities. The resulting PMSP for Texas cotton will help the Texas cotton industry work more effectively with university research and extension systems and others involved in Texas cotton pest management. This strategic plan will help the grower community and federal and state programs to direct resources to the most critical issues for Texas cotton producers.

The primary objective of this strategic plan is in identifying the research, regulatory, and educational priorities for cotton pest management as identified by the growers themselves. It will serve as a guideline to direct future pest management efforts related to Texas cotton production. The mention of specific trade names in this document is not an endorsement of any particular product.

Stakeholder recommendations

Two PMSP planning meetings were held to identify the research, regulatory, and educational priorities for the Texas cotton industry. The first meeting was held in May 2004 in Corpus Christi and the second meeting in January 2005 in Lubbock. Growers, commodity representatives, research and extension personnel provided the input necessary to complete this document.

Philosophy

The overall IPM strategy in Texas cotton, with the exception of pests under eradication programs, is to find levels of insect, weed, and disease infestations that permit producers to produce cotton profitably with optimum levels of economic inputs per production unit with a maximum profitability per unit.

Production facts

Texas leads the U.S. in cotton production. In 2004, Texas cotton growers planted 6 million acres of cotton. This exceeds 9,300 square miles and is a land area larger than combined total land areas of Connecticut, Delaware and Rhode Island. It is also larger than the total land area of Hawaii, New Jersey, Massachusetts, New Hampshire or Vermont. Cotton is the leading cash crop of Texas and ranks only behind the beef and nursery industries in total cash receipts. In any one year, Texas cotton growers produce between 4 and 6 million bales. This represents more than $1 billion to the Texas economy and is between 25 and 30 percent of the entire U.S. crop.

Production regions

The slogan, "Texas is like a whole other country," from a cotton production perspective is certainly appropriate. For example, when producers start planting in the Rio Grande Valley in February, the High Plains is still locked in winter. When the first bale is harvested in the Rio Grande Valley in July, High plains cotton growers have just finished planting. In most years, the harvest season is about six months long, starting in the Valley in July and finishing on the High Plains and Trans Pecos in December. In fact, every season, many custom harvesters start their season in the Lower Rio Grande valley and make the northern trek following the harvest from there to the Texas High Plains.

4 Geologists divide the physical geography of Texas into sixteen main regions. Within this diverse physical environment, ecologists have identified ten principal ecological regions (ecoregions) defined generally by ten distinct vegetational areas (Fig 1). Within these distinct regions, agronomists have identified seven cotton production regions characterized by distinct growing seasons, soils, rainfall, adapted varieties and production practices.

Fig. 1. Texas vegetational regions.

The seven cotton production regions include are designated by the vegetation region or regions in which they lie (Fig. 1). They include the Lower Rio Grande Valley (composed of the subtropical riparian zone at the southern limit of the South Texas Plains), High Plains, Trans-Pecos, Rolling Plains (composed of the Rolling plains and in part of the Cross Timbers), Blacklands, Eastern Texas (composed of the Pineywoods and Post Oak Savannah) and, South Texas (composed of the Coastal Prairies and interior South Texas Plains). Each region differs from the others with respect to climate, soils, cultural practices, the pest, disease, and weed and native plant complex, cotton varieties, and even the species of cotton grown.

East Texas. The Eastern Texas cotton production area includes two huge regions known as the Pineywoods and the Post Oak Savannah. The Pineywoods is located in eastern Texas and covers over 15 million acres. It is well-watered, gently rolling to hilly forested land that consists of the western terminus of the contiguous southern pine forest extending south and east to the Atlantic Coast. Upland soils are generally acid, sandy loams and sands over varying subsoils. Bottomland soils are generally acid to calcareous, clay loams. It receives up to 45 inches of precipitation per year, and cotton is grown entirely under conditions of rainfall. Farms have been cleared out of the forest, and cotton production practices, adapted

5 varieties and the complexes of pests, diseases and weeds are similar to those in the Midsouth and Southeastern United States.

The Post Oak Savanna, also known as Oak Woods and Prairies, is a large region of approximately 19,000 square miles. Landforms are mostly of gently rolling to hilly landscape. The bottomland soils range from sandy loam to clay, while the prairies have sandy loam or sands. It forms a somewhat drier portion of the coastal plain where dominant vegetation consisted of open grasslands with small patches of forest characterized by post oak and other hardwood trees. Farms were plowed out of the grasslands, and production practices are most similar to those of the Midsouth. Cotton is produced mostly under conditions of rainfall, but supplemented in a few locations with irrigation during drier periods of the summer. The pest, weed and disease complexes are most similar to those of the Midsouth.

Eastern Texas produces about 4% of the Texas cotton crop. Less than 1% of the cotton is irrigated. Production is primarily short-season varieties. This avoids adverse fall weather and a great deal of late-season pest pressure. More than 95% of the crop is stripped.

The Blacklands. The Blackland Prairie region is gently rolling and level land covering about 23,500 square miles, extending from the Red River north of Dallas southward through Austin to an area just south of San Antonio. It is named for the rich, deep, fertile black soils that once supported the original tallgrass prairie communities and, due to land-use change, today support crop production and cattle ranching. About 98 percent of the Blackland Prairie is cultivated and now is more commonly called the Blacklands.

The Blacklands production area also includes the eastern portion of the Crosstimbers and Prairies region, often referred to simply as the Crosstimbers area. This is an area of Texas consisting of two broad belts of wooded prairies between the Blacklands and the Rolling Plains. It extends southward from the Red River to the Edwards Plateau. About 25 percent of this area is cultivated farmland, while the rest is used as range and pasture.

Both the Blacklands and adjacent prairies are an extension of the tallgrass prairie system of the Central United States. Farming practices in this region are about the same as in the Blacklands Prairies with only the characteristic soils and native climax vegetation being different. This region produces 4% of the state's total cotton crop. Deep prairie soils predominate this region. Temperate, warm nights and adequate rainfall (30-36 inches a year) lead to the fact that only five percent of this region is irrigated. At harvest, 95% of the cotton is stripped.

South Texas. The South Texas production region includes the Gulf Coast Prairies and Marshes and the inland, semi-arid South Texas Plains. The Gulf Coast Prairies and Marshes is a nearly level plain of more than 13 million acres. It borders the Gulf of Mexico from Louisiana to Mexico, with the most characteristic section extending from the Sabine River to Corpus Christi Bay. About one-third of the area is farmland.

Most of the cotton in this region is produced in the deep, rich soils of the Coastal Prairies in an area known as the Coastal Bend. This region occupies a part of the coastal plain about 100 miles wide, extending from Jackson and Victoria Counties on the north to Kenedy County immediately south of Corpus Christi. About one-third of the area is farmland and produces about 8% of Texas cotton under warm temperate conditions with very high humidity and comparatively abundant rainfall. The Coastal Bend receives 25 to 32 inches of rainfall per year. Ninety percent of the cotton produced in this region is grown under dryland conditions with only 10 percent receiving irrigation of any type. Most of the cotton produced in the Coastal Bend is harvested with spindle pickers.

The South Texas Plains, also known as the Brush Country is an area that lies inland from the Gulf Prairies and Marshes and encompasses approximately 18 million acres. It is a semi-

6 arid inland region extending from slightly north of San Antonio south to the Mexican border and Rio Grande River. It includes the Texas Wintergarden area and Del Rio. Geographically, the South Texas Plains are an area nearly level to rolling, generally increasing in elevation to the west. It was once covered with open grasslands and a scattering of trees, but the original grasslands have become shrubland due to overgrazing. Today the area is characterized by thorny shrubs and cacti, including mesquite, acacia, and prickly pear. In the river valleys are patches of palms and subtropical woodlands. It has shallower soils and receives less rainfall, and ranching is the major land use. However, irrigated and dryland cropping of cotton, grain and forages are also important. Most cotton produced in this inland region receives supplemental irrigation. Cultivation and harvesting practices are similar to those employed in the Coastal Bend.

In the southern part of the Gulf Coast Prairies and Marshes is an area known to some ecologists as the Coastal Sand Plains, a small ecological region somewhat distinct from the rest of the South Texas Plains occupying about 2.5 million acres. The vegetation of this area can be described as grasslands with coastal oak motts, mesquite, granjeno, and salt marshes. It is home to the King Ranch, which in the past ten years has begun to plant extensive acreages of dryland cotton, produced primarily on a short-season plan.

Lower Rio Grande Valley. Lower Rio Grande Valley production area is a narrow, subtropical river flood plain adjacent to the border with Mexico, extending from the Falcon Dam in Starr County near Rio Grande City to the Gulf of Mexico near Brownsville. Although the Lower Rio Grande Valley is part of the South Texas Plains ecoregion and vegetational zone, its subtropical climate, farming practices and crops separate it from the rest of the South Texas Plains as a distinct cotton production region. This region plants early due to the warm temperate to subtropical climate. Average rainfall is between 25 and 30 inches per year and 60% of the crop is irrigated. Seventy percent of the cotton is picker harvested. This area produces 3% of the state's crop. Along the margins of the Lower Rio Grande Valley in an area identified on ecological maps as the Sand Prairies producers plant dryland cotton, which is grown under a short-season production regime. The Lower Rio Grande Valley is far enough south to reside in the Neotropical climatic zone. During the rainy season of the American tropics, it receives enough rainfall to mature short-season cotton.

High Plains. The High Plains, extending north and south of Lubbock, is an enormous region covering approximately 32,000 square miles. It is a southern extension of the Great Plains of the central United States. Near the surface of much of the Texas High Plains are layers of resistant caliche known as "the caprock." The eastern boundary is the Caprock escarpment. The western boundary is the Mescalero Escarpment east of the Pecos River valley. The southern end of the plateau lacks a distinct physical boundary but blends into the table lands of the Edwards Plateau and Colorado River drainage east of Big Spring. It includes all or part of thirty-three counties in Texas and four in New Mexico. The regions was formerly called the Llano Estacado during the Spanish Colonial period.

It is a semiarid region with average annual precipitation of eighteen to twenty inches. The soils are almost universally dark-brown to reddish brown sands, sandy loams, and clay loams. High winds, dry winters and low annual rainfall present problems for cultivation and erosion control. Water-bearing areas of the High Plains are hydraulically connected except where the Canadian River has partially or totally eroded through the water-bearing formations to separate the North and South Plains. Several major aquifers provide irrigation water to the High Plains, including the Ogallala, Rita Blanca, Edwards-Trinity and Dockum. Underlying these are several other minor aquifers. Cotton farming and cattle ranching are the major agricultural industries. As the cost of lifting water to the surface increases and ground water diminishes, use of pasture and range for livestock production has increased.

Twenty-seven counties in the High Plains produce 64% of the Texas cotton crop. This is about 20 to 25 percent of the total U. S. cotton crop. The hot days and cool nights plus loam

7 and sandy soil types make it vital to implement water and soil conservation methods. Fifty percent of the cotton is irrigated in this region. Average rainfall is 16-22 inches, but there are wide year-to-year variations in both total and seasonal rainfall. The elevation and northern latitude impose a short-season production strategy on cotton producers. Cotton varieties are highly determinant and selected to mature in the short season available. At harvest, 98 percent of High Plains farmers strip their cotton.

Rolling Plains. The rolling plains in North-Central Texas cover approximately 28 million acres. This area, along with the High Plains, is the southern end of the Great Plains of the central United States. The northern boundary of the Rolling Plains is the Red river and the southern boundary is the Edwards Plateau. The Cap Rock Escarpment east of Lubbock is a cliff that runs north to south to separate the Rolling Plains from the High Plains. The southern end of the Rolling Plains include the St. Lawrence Area and Concho River Valley around San Angelo. The eastern boundary of the Rolling Plains region is the Grand Prairie section of the Crosstimbers region, but this area, including the Grand Prairie is sometimes included in the Rolling Plains cotton production area. Crop and livestock production are the major agricultural industries of this region. Twenty-four counties in this region produce 20% of Texas cotton. Depending upon the year, this is between 5 and 10 percent of the national cotton crop. Moderate to hot days and cool nights characterize this region. Ten percent of the cotton is irrigated. Rainfall varies from 20-24 inches of rain a year on the sandy loam to loam soil. The stripper method of harvesting dominates 98% of this region.

Trans Pecos. The Trans-Pecos region is the northern portion of the Chihuahua desert. It is the most complex region of the state. The Trans-Pecos region is located between the Pecos River and El Paso. It is a true hot desert environment. Rainfall averages 4-14 inches per year, and summer temperatures often exceed 110° F. It includes plateaus, desert valleys, and wooded mountains. The only true mountain ranges in Texas are in the Trans-Pecos. The Trans-Pecos area is traversed by the eastern chain of the Rocky Mountains, and the intermontaine valleys of west Texas are part of the enormous province known as the Basin and Range Province that extends from the western slopes of the Rockies to the eastern slopes of the Sierras. The Rio Grande River creates the region's southern border, separating Texas from Mexico. The Mescalero Escarpment east of the Pecos Valley marks its eastern limit.

Land use consists mostly of cattle ranching, but many minor aquifers in the desert valleys provide irrigation water for crop production. Limited amounts of irrigation water are also available from the Pecos River in Pecos and Reeves Counties, and the El Paso Valley (El Paso and Hudspeth Counties) receive substantial irrigation water from the Rio Grande. Alluvial and desert soils predominate. High temperatures and a long growing season favor production of full-season, indeterminate cotton varieties. Irrigation is essential and is practices in one form or another on 100 percent of planted acres. Depending upon the location and varieties, fifty to ninety-five percent of the crop is picker harvested. Varieties and cultural practices are similar to those planted in New Mexico, Arizona and California. Akala and similar varieties of upland cotton (Gossypium hirsutum) predominate, but some Pima (G. barbadense), also known as extra long staple cotton, also is produced.

Irrigated Production

Plan and conduct production practices to achieve early crop maturity in order to escape late-season insect attack and population buildup of insect pests. Production inputs should be directed toward maximum crop profit instead of maximum crop yield. Crop management practices that have an impact on insect pest numbers and crop damage are:

! Varietal selection (short-season or full-season varieties). Short-season varieties usually mature earlier and escape late-season pest problems which often occur on late-season varieties.

8 ! Uniform planting dates. Allow fields in an area to mature together. Pest infestations are prevented from developing in earlier planted fields and moving into later planted fields.

! Plant population on irrigated cotton should range from 35,000 to 65,000 plants per acre (2.5 to 4.5 plants per foot on 40-inch rows) in most areas. Larger plant populations can cause delayed crop maturity due to competition for water, nutrients and sunlight. Overcrowding may also contribute to undesirable stalk growth.

! Amount of nitrogen fertilizer used and application timing. Excessive or late nitrogen applications delay crop maturity, particularly when coupled with late irrigation, and subject the crop to intensified and prolonged attack by cotton bollworms, tobacco budworms, boll weevils and pink bollworms.

! Weed control. Weeds limit yield by competing directly with cotton plants for water and nutrients; they also attract various insect pests into cotton fields.

! Amount and timing of crop irrigations. Timing of irrigations often is more important than the total amount of water applied. Water use by the cotton plant is very low during the 35- to 40-day period from seed emergence to the appearance of the first square. Water use increases rapidly with the appearance of the first square. Maximum water use is reached during peak bloom. As the plant progresses toward maturity, water demands are reduced.

Flowering is the period of most rapid plant growth and development when more than half of the total water is used. Excessive irrigation during this period may make plants more attractive to bollworm and tobacco budworm because of additional vegetative growth. Excessive vegetative growth can be checked by allowing sufficient depletion of available water before each irrigation. Excessive water will delay crop maturity, thus increasing crop susceptibility to attack from bollworms, tobacco budworms, boll weevils and pink bollworms.

The final irrigation should be timed to provide enough moisture to mature the bolls set during the first 4 weeks of boll production in upland and Acala cotton, and to mature the bolls set during the first 6 weeks in Pima cotton. Fruit produced as a result of late irrigations not only adds little to final yield, but also delays the opening of mature bolls, increases crop susceptibility to insects, induces boll rot and contributes to defoliation problems. Late set bolls normally have a poor probability of producing fiber and the lint produced from these bolls is generally of poorer quality because of immature fibers and insect damage.

Crop irrigation should terminate at least 10 days prior to a predicted peak in bollworm egg-laying. This will reduce plant attractiveness to bollworm and budworm moths, lower field humidity to suppress egg hatch and limit the amount of young, tender growth available for newly hatched worms to feed on.

Dryland Production

The primary factor limiting dryland cotton production is the lack of adequate moisture prior to and during the growing season. Due to the lack of moisture or the formation of a hardpan, cotton plants may be unable to develop an adequate root system. Dry conditions and moisture stress after cotton begins to fruit will cause the cotton plants to abort squares and small bolls, often reducing or completely negating any potential yield increase obtained from pest control. The amount of moisture in the soil profile at planting appears to be the most accurate predictor of potential based on the anticipated yield. Because the yield potential of dryland cotton is generally moderate to low, insecticides and other inputs such as fertilizers should be based on realistic yield goals.

The yield potential of cotton planted after June 20 is greatly reduced; average yields can be expected only in those years when warm conditions extend well into October. Because of the

9 limited yield potential, additional benefits from the management of insects are also limited. An insecticidal application can be expected to result in a positive economic return only when expected damage equals or exceeds the insecticide and application cost.

Information on cotton varieties that perform best under dryland conditions can be obtained from county Extension agents who annually conduct cotton variety demonstrations. Short-season fruit and mature more rapidly than Delta-type varieties; consequently, the short-season varieties are subject to insect damage for a shorter period of time and may escape the development of large late-season insect populations. Fertilization of dryland cotton should be based on a soil test.

Plant dryland cotton so that there are 26,000 to 53,000 plants per acre (two to four plants per foot on 40-inch rows). Higher plant populations cause greater competition between plants for moisture and nutrients and can lead to increased pest damage. Severe bollworm problems can occur in either wet or dry years; however, wet conditions, which favor succulent growth, are generally more favorable for bollworm survival. Bollworms and aphids may become a problem following an insecticide application which destroys beneficials. Insecticides should be applied only when necessary, as determined by frequent field inspection.

Cotton production in the Eastern, Southern and Blacklands regions

The short-season cotton production system is crucial in reducing insect damage. This system includes cultural practices such as: 1) early, uniform planting of cotton varieties which bloom and set bolls early, mature rapidly and are ready to harvest 130 to 150 days from planting (refer to county cotton demonstrations for varieties that have performed well in your area); 2) optimum use of fertilizer and minimum irrigation; and 3) early, complete stalk destruction. These practices shorten the time that cotton is vulnerable to insect attack, minimize potential damage from adverse weather, and allow more time to prepare land for the next crop. Failure to implement these cultural practices will increase the probability of late-season insect pest outbreaks, increase the need for insecticides and cause larger populations of overwintering pests to develop.

The first 30 days of blooming are critical for early boll set. The earliness factor in short-season production can be lost when damaging populations of insects occur as the first squares are formed. Loss of first squares to overwintered boll weevils also will detract from short season production. To ensure early fruit set, scout fields to determine pest population levels and plant damage, as well as beneficial insect numbers and cotton fruiting rate. Use chemical insecticide only when justified. Insecticides may destroy natural enemies of cotton insect pests, causing increased numbers of bollworms, tobacco budworms, spider mites and cotton aphids.

Cotton production in the Lower Rio Grande Valley

Currently, cotton production in the Lower Rio Grande Valley includes both short-season and full-season production schemes. Short-season cotton is produced with reduced or supplemental irrigation and uses highly determinate varieties. Cutout is induced by withdrawing irrigation, after which limited supplemental irrigation may be required to mature the crop. The short-season production system in the Lower Rio Grande Valley is designed primarily to reduce risk through a shortened exposure period to hazards from weather and insect pests.

In the production of full-season cotton, producers take advantage of the Valley's long growing season to produce higher quality, higher yielding indeterminate varieties. These varieties usually take more water to mature and more fertilizer to produce higher yields. However, they are much more resistant to drought stress and high summer heat which are common in the Valley. Although there is a higher risk from increased exposure to weather

10 and insect damage during the longer season, the indeterminate varieties compensate with an increased ability to set fruit under the conditions present in the Lower Rio Grande Valley. Although these varieties receive more irrigation throughout the production period, cutout is induced by withdrawing irrigation. These varieties also require more water to mature their heavier crop than do short-season varieties.

Full-season production

In the Lower Rio Grande Valley and in the Trans Pecos region, the full-season production system has been practiced for many years. This system uses slower fruiting, indeterminate, full-season varieties grown with higher nitrogen inputs (greater than 40 pounds per acre) and abundant irrigation. The result is a long-season production period of 140 to 160 days from planting to harvest. This system requires higher inputs and has proven to be a profitable method of cotton production in past years. In the desert valleys of the Trans Pecos high summer temperatures, the high costs of required irrigation and irregularities of spring weather make the planting of higher yielding, full-season, indeterminate cotton varieties more advantageous. The hot, arid climate of Trans Pecos region makes this the only area of Texas where Pima cotton can be produced profitably. Even the shorter season Pima varieties require considerably more time to mature than full season upland cotton.

Production costs have increased greatly in recent years in the Lower Rio Grande Valley and Trans Pecos. Increasing nitrogen fertilizer, cost of irrigation water and energy costs all have added extra expense, prolonged fruit development and delayed maturity of both upland and Pima crops. These factors expose the cotton to increased risk from continuously increasing populations of late-season pests such as the boll weevil, cotton bollworm, tobacco budworm and pink bollworm. A major production cost in full-season upland cotton and in Pima cotton is the multiple applications of insecticides to protect the crop throughout the longer fruiting period. Consequently, high yields must be obtained to offset these high production costs. The probability of crop loss from delayed harvest because of adverse fall weather conditions is greater under this production system.

Full-season cotton varieties can be grown under a short-season production regime where soil types and rainfall allow. Early planting in combination with reduced nitrogen (40 pounds or less) and water levels, where applicable, result in a somewhat shorter production period. Nitrogen required for cotton production depends on the previous crop planted, nitrogen recycling, fall precipitation and soil types.

Bt transgenic cotton

Bt cottons are insect-resistant cultivars and one of the first such agricultural biotechnology products to be released for commercial production. Insect resistance in the Bt cottons was engineered by the introduction of a bacterial gene that produces a crystalline toxin, which, in turn, kills feeding larvae of several cotton pests. The toxin in Bollgard® cottons has excellent activity against tobacco budworm, pink bollworm, cotton leaf perforator and European corn borer, and good activity against cotton bollworm, saltmarsh caterpillar and cabbage loopers. When the infestation is heavy, supplemental insecticide treatment may be necessary for bollworm. Bt cottons, principally Bollgard® varieties provide some suppression of beet armyworm and soybean looper, but little or no control of fall armyworm or cutworm. Recently released cotton varieties such as Bollgard® II, which combines Cry1Ac and Cry2Ab Bt endotoxins, and WideStrike®, which combines Cry1Ac and Cry1F Bt endotoxins, are more effective against all of the mentioned caterpillar pests, except cutworms. In all cases, economic thresholds used for Bt cottons should be the same as those used for non-Bt cottons, but should be based on larvae larger than 1/4 inch and damage, not on eggs or early instar larvae.

11 Early stalk destruction and field cleanup

Early harvest and stalk destruction are among the most effective cultural and mechanical practices for managing overwintering boll weevils if done on an area-wide basis. These practices reduce habitat and food available to the boll weevil, pink bollworm, bollworm and tobacco budworm. Where cotton is harvested before a killing frost, cotton should be shredded at the earliest possible date to prevent regrowth which can provide squares for weevils to feed on and allow them to successfully overwinter. This cotton provides the boll weevil with a host plant on which reproduction occurs throughout the year. Weevil infestations that are allowed to develop during the winter may result in extremely high populations during the following season. Stubble regrowth or volunteer seedlings must not be allowed to remain within fields, in surrounding field margins or on drainage system banks. In the High Plains, Rolling Plains and Trans Pecos regions, when cotton is not harvested until frost, stalks may be left standing in the field except in areas where the pink bollworm is a problem. In areas of pink bollworm infestation, stalks must be shredded and plowed under to a depth of 6 inches. Green or cracked bolls left at the ends of rows should be destroyed to reduce pink bollworm populations.

Particular attention should be given to the destruction of green or cracked bolls and other plant debris left at the ends of rows following stripper harvest. Cotton present during the fall and winter months is illegal in the Rio Grande Valley, and in most counties in the Lower Coastal Bend, South Texas and the Blacklands stalk destruction must be complete by the start of winter. In the Trans Pecos region, cotton stalks must be destroyed before the end of winter months. Cotton Pest Regulations, available from the Texas Department of Agriculture, specify cotton destruction dates for each area and county. If a thorough stalk destruction program is not carried out, the benefits of the pest management program will be reduced significantly.

The addition of 0.5 lb. ai/acre methyl parathion or 0.25 lb. ai/acre azinphos-methyl (Guthion®) to phosphate-type defoliants has proven effective in reducing potential overwintered boll weevils. Do not add methyl parathion or azinphos-methyl to chlorate-type defoliants because of the potential fire hazard. The use of insecticides at defoliation will be effective only if stalk destruction is promptly performed following harvest. The greatest impact from insecticides is realized when applied on an area-wide basis. If 3 to 4 weeks elapse between defoliation and stalk plow-up, the money spent on insecticides at defoliation will provide less benefit in boll weevil management. Weevils will continue to emerge, feed, reproduce and move from cotton fields following harvest.

Stalk destruction laws

Upon request and petition of Texas Cotton Producers, the Texas Legislature passed the Cotton Pest Control Law in an effort to combat the boll weevil and pink bollworm. This law, which is enforced by the Texas Department of Agriculture, requires producers in a regulated county to culturally manage pest populations using habitat manipulation by planting and destroying cotton within an authorized time period. Appointed producers, who are members of local pest management zone committees, have established a series of cotton planting and stalk destruction deadlines for all producers in each regulated county. The battle against pink bollworms has been extremely successful. Because farmers have adhered to authorized planting and stalk destruction deadlines over the past years, pink bollworm populations in most of the state have been reduced to levels that do not cause major economic damage. Boll weevil population control through stalk destruction efforts has been significant but more growers need to be involved in the effort. Strict adherence to the established deadlines is critical to success of boll weevil management.

12 Insect and Arthropod Pest Management

Cotton in the Texas is host to more than twenty different species of insect and arthropod pests. Each of these pests is capable of causing economic yield loss, and several key pests, such as the cotton fleahopper, boll weevil, cotton bollworm, tobacco budworm and pink bollworm, are capable of completely destroying a crop. Historically the boll weevil has ranked as one of the most damaging pests of Texas cotton. However, the bollworm/tobacco budworm complex, pink bollworm, plant bugs (Lygus spp. and Creontiades spp.), beet armyworms, other armyworms, cotton leafworms, saltmarsh caterpillars, cotton square borers, cotton aphids, stink bugs, grasshoppers and thrips have also caused high levels of damage in some years.

Several insects attack cotton at various stages of growth. The major insect pests of cotton grown in Texas are the boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), cotton fleahopper (Pseudatomoscelis seriatus), plant bugs (Lygus spp.), and aphid (Aphis gossypii). Other arthropod pests of cotton, include the beet armyworm (Spodoptera exigua), fall armyworm (S. frugiperda), cutworm (Agrotis ipsilon, Feltia subterranea and others), stink bug (Nezara viridula, Euschistus servus, Acrosternum hilare, Chlorochroa ligata and others), western flower thrips (Frankliniella occidentalis), onion thrips (Thrips tabaci), loopers (Pseudoplusia includens, Trichoplusia ni and others), whiteflies (Bemisia spp.), and spider mite (Tetranychus urticae). The insecticides used to control the major arthropod pests are found in efficacy tables 1 through 22.

Cotton growers may invest more than $500 to produce an acre of cotton, and all of this investment is potentially at risk to insect damage. The cost of controlling insects is one of the larger items of the crop production budget, annually averaging from $70 to over $100 per acre.

Cotton producers utilize a variety of non-insecticidal management tools (Table 1) to limit the number of times that pests exceed economic thresholds and consequently require treatment with insecticides. However, timely, judicious use of insecticides is an important component of cotton IPM. Recommendations for cotton insect management are published in the various insecticide recommendations revised yearly by the states' Extension Service.

Because pest populations can change quickly, cotton insect management is both information intensive and time sensitive. During the growing season, fields must be scouted every three to four days, and accurate estimates of pest populations must be determined by time consuming sampling procedures. Because of the time involved in making these counts most producers use Extension IPM programs coordinated by Extension Agents-IPM and scouted by field scouts employed by the grower-owned Texas Pest Management Association (TPMA), independent professional crop advisors (PCAs) who employ part-time scouts, and certain agricultural chemical industry and farm supply representatives, to provide most of the monitoring or scouting.

During recent years there have been significant changes in Texas cotton IPM systems, which continue to evolve rapidly. These changes are occurring because of three major factors: 1) widespread planting transgenic Bt cotton, 2) boll weevil eradication, and 3) new, more highly selective, target-specific insecticides.

In recent years from 70 to 80% of Texas cotton acreage has been planted to Bt transgenic cotton varieties. Because Bt cotton is highly effective against larvae of several pest Lepidoptera, including tobacco budworm, pink bollworm, and several species of leaf and boll feeding caterpillars. Fields planted to Bt varieties require significantly fewer treatments for these pests. Bt cotton is also effective against bollworms, but to a lesser degree, occasionally requiring treatment for control of bollworms. However, since Bt cotton was first

13 introduced in 1996, Bt fields have consistently required fewer treatments than non-Bt fields for caterpillar pests, while also sustaining less boll damage.

During the past several years a number of new insecticides, belonging to novel classes of chemistry, have been developed, or are being developed, for use in cotton. These include products such as spinosad (Tracer®®), indoxacarb (Steward ), and thiamethoxam (Centric®). While these products are quite effective against their primary target pests, they tend to control a narrower spectrum of pests than most of the older products. This can be advantageous, when there is a need to control only one pest, because the increased selectivity fosters conservation of beneficial insects. However, when there is a need to control multiple pest species, tank mixing multiple insecticides can offer distinct economic and ecological disadvantages.

Together, the broad adoption of transgenic Bt cotton, combined with the progress of the boll weevil eradication effort has resulted in significant reductions in the number of foliar sprays applied by Texas cotton producers. Unfortunately, this reduction in the number of foliar insecticide treatments has not provided a corresponding decrease in the per acre cost of cotton insect control. This is because of offsetting costs associated with "technology-use fees" for Bt cotton, assessment fees to fund boll weevil eradication efforts, and increased costs of newer insecticides. Still, boll weevil eradication and Bt cotton have had the very positive impacts of reducing the risks of insect induced yield losses, reducing overall use of insecticides, and reducing the physical and logistical effort that growers must devote to insect management.

One consequence of this new pest management system under which cotton is grown in the Texas has been a shift in the overall pest complex. Pests such as boll weevils, bollworms, tobacco budworms and pink bollworms are of much less concern than they were in past years, because of the direct effects of boll weevil eradication and Bt-cotton. The reduction in foliar sprays has also had an indirect effect in reducing outbreaks of secondary pests, such as cotton aphids and beet armyworms. However, pests such as tarnished plant bugs and stink bugs have thrived in this reduced spray environment and the number of treatments applied specifically to control these pests has increased.

Insect populations vary with Texas production region. The Eastern, Southern, Gulf Coast, Southern Blacklands and Lower Rio Grande Valley tend to have somewhat different insect problems than the High Plains, Northern Blacklands, Rolling Plains and Trans Pecos production regions. In the High Plains, Northern Blacklands and Rolling Plains, shorter growing seasons combine with much cooler winters to reduce overwintering survival of several key insect pest populations. The higher elevations, arid climate, complete dependence on irrigation and other cultural practices of the Trans Pecos region have produced a significantly different pest complex than in other parts of the state, the most important of which is heavy mid- to late-season pressure by pink bollworm.

Early-season pests

The early-season is the period extending from plant emergence to first 1/3-grown squares. Pests that affect cotton during this growing period can be easily divided into those affecting the crop through stand reduction prior to squaring and those affecting crop through yield reduction from destruction of fruiting forms. Early-season pests that destroy the crop through destruction of entire plants during earliest growing stages include thrips, cutworms, aphids, grasshoppers, caterpillars and whiteflies. Pests that regularly destroy the crop by eliminating early fruiting forms (pinhead to 1/3-grown squares) include cotton fleahoppers (Pseudatomoscelis seriatus), plant bugs (Lygus and Creontiades spp.), stink bugs and overwintered boll weevils (Anthonomis grandis). Scouting and management of these early-season insect pests are extremely important, particularly in a short-season production schemes.

14 Only two insects are considered key early-season pests of cotton throughout Texas. These are the cotton fleahopper and the overwintered boll weevil. Others regarded as occasional pests of early-season cotton throughout Texas include thrips, aphids and plant bugs. In the Trans Pecos region, pink bollworm occasionally appears early enough to damage small squares. Loss of early, first-position squares to fleahoppers, overwintered boll weevils, plant bugs or pink bollworms may prolong the length of the growing season required to obtain adequate fruit set.

Some early-season pests are regional. In the Lower Rio Grande Valley, occasional outbreaks of Bemisia species of whiteflies sometimes cause damage. In Eastern, Southern and the Blacklands areas, cutworms occasionally reduce stands as seedling cotton plants emerge from the soil. In South Texas and West Texas several species of early hatching grasshoppers and grasshoppers overwintering as nymphs and adults occasionally damage early-season cotton from the seedling through early squaring stages of growth.

Stand destroying pests

Thrips

Two species of thrips damage Texas cotton. These are Western flower thrips (Frankliniella occidentalis) and onion thrips (Thrips tabaci). Both species are slender, straw colored insects about 1/15 inch long, with piercing-sucking mouthparts. Adults are winged and capable of drifting long distances in the wind. Thrips attack leaves, leaf buds and very small squares, and may cause a silvering of the lower leaf surface, deformed or blackened leaves, terminal loss and square loss. Under some conditions, heavy infestations may reduce stands, stunt plants and delay fruiting and maturity. In most production areas, thrips damage is most evident during cool, wet periods when small cotton is growing slowly. In the Trans Pecos region, thrips damage may also be observed during times of intense sunlight and dry, warm, winds, during which cotton growth slows due to high evapotranspiration rates. Thrips damage often is further compounded by plant damage resulting from rain, wind, blowing sand and diseases.

In many areas, particularly the Trans Pecos region and the Lower Rio Grande Valley, thrips are considered only as occasional or minor cotton pests. Under favorable growing conditions, cotton can sometimes recover completely from early thrips damage. However, early infestations are often difficult to detect until after damage symptoms appear. Thrips often infest the folded small leaves of the plant terminal and are difficult to count unless the terminal area is dissected. This is especially true during rainy or windy conditions. Early-season infestations under these conditions often reduce yield more than later infestations.

In the High Plains, thrips problems often require treatment. Thrips are more prevalent in areas with extensive planting of winter wheat and where producers plant before late May or early June. Thrips migrate in heavy numbers from adjacent weeds or crops, particularly winter wheat. In the High Plains, extensive thrips migrations from maturing small grains often occurs at the same time as seedling cotton emerges. These migrations can cause significant damage within a few days and prior to the appearance of true leaves. The comparatively short growing season in the High Plains does not provide enough time for cotton plants to recover from the delayed fruiting that results from thrips injury.

Thrips are a minor pest in the Lower Rio Grande Valley and rarely require treatment. Most thrips problems occur in cotton fields located near onion fields. Heavy migrations to cotton fields may occur from fields of maturing onions. Under cool, wet conditions, heavy infestations can retard recovery cold stress and delay fruiting. Generally, about the time thrips reach damaging numbers, favorable growing conditions negate the need for control.

15 Thrips management and decision making. The decision to apply insecticide should be based on the number of thrips present and the stage of plant development. Inspect cotton from the cotyledon stage through the 6-true-leaf stage. The decision to apply insecticide should be based on the number of thrips present and the stage of plant development. The number of thrips per plant to use as a treatment level increases as plants add more leaves. Control may be justified when the average number of thrips counted per plant is equal to the number of true leaves present at the time of inspection. One thrips per plant should be used as the treatment level from plant emergence, through the cotyledon stage, to the first true leaf. Inspections should begin once cotton has reached approximately 50 percent stand emergence. Insecticidal control is rarely justified once plants reach the 5- to 7-true-leaf stage, or when plants begin to square.

In areas with a history of frequent, heavy thrips infestations, the use of systemic insecticides should be seriously considered. Applications of systemic insecticides as seed treatments provides effective control of thrips. Disulfoton (Di-Syston®®), phorate (Thimet ) and imidacloprid (Gaucho®) seed treatments will effectively control thrips for 1 to 4 weeks following plant emergence under good growing conditions. Planterbox seed treatments also control early-season thrips. Applications of systemic insecticides as banded treatments of granular formulations at planting in the seed furrow provide effective control of thrips through the early squaring period. Granular formulations of aldicarb (Temik®®, disulfoton (Di-Syston ) and phorate (Temik®) applied in the seed furrow at planting will control thrips for 4 to 8 weeks. However, applications at higher labeled rates can reduce natural enemies and lead to secondary pest problems. In the Lower Rio Grande Valley, higher labeled rates of systemic insecticides applied at planting sometimes result in greater numbers of bollworms and tobacco budworms later in the season.

Research has shown that the application of foliar sprays after significant thrips damage has occurred generally does not result in increased yields. Where postemergence sprays are to be used, fields should be scouted as often as twice a week as cotton emerges. Research also shows that cotton varieties with hairy leaves are less injured by thrips than smooth-leaf varieties.

After severe aphid outbreaks and severe losses to apparently insecticide resistant aphids in 1990 and 1991, Texas A&M University Cooperative Extension established the Texas A&M University Cotton Aphid Task Force composed of Extension and Research Entomologists. In 1992, the task force recognized the potential for insecticide resistance in aphids and issued the following guidelines:

Insecticide use must be developed with a 'resistance management' strategy. For cotton production, the Texas A&M University Cotton Aphid Task Force has suggested the following management practices.

! Planting dates must be optimized to escape times of the year with high aphid populations.

! Planting must ensure an adequate and uniform stand.

! Excessive nitrogen must be avoided through fertilizing based on soil tests. Minimize the use of acetylcholinesterase inhibiting insecticides early in the season, particularly aphicides, such as dicrotophos, methomyl and chlorpyrifos. Because the cotton aphid has the ability to develop resistance to all classes of insecticides, maintaining effective insecticides through conservative use, rather than alternating insecticide classes, appears to be the most valuable approach. Delay insecticidal control of aphids until aphids exceed economic threshold levels (50 aphids/leaf in cotton). Use higher labeled rates of effective insecticides for aphid control When pyrethroids are applied for other pests an aphicide may be added. Maximize insecticide coverage on lower plant parts.

16 Cutworms

Cutworms are occasional pests that damage cotton during the seedling stage, and control will be necessary if stands are threatened. Cutworms are one of the few cotton pests that are capable of killing an entire cotton plant. Larger larvae feed by cutting the main stem of seedling plants. When plants are cut below the cotyledon node, the entire plant is killed, and this is the most common type of injury, especially in plants younger than the 3-leaf stage. Occasionally larger seedlings are cut above the cotyledon node, and plants damaged in this manner often survive, although they may be less productive. Cutworms have the potential to cause very heavy yield losses if stands are destroyed or severely reduced and fields are not re-planted.

In practice, cutworms seldom cause heavy yield losses. This is because cotton has the ability to compensate for low to moderate level stand loss, and because fields are routinely re-planted, or "spot re-planted" in cases where stand loss is excessive. Thus, the greatest loss associated with cutworm damage is the cost of replanting, which is substantial, and any yield reductions or increased production costs associated with later planting.

Cutworms that occur in Texas belong to four major groups. Based on habitat and feeding behavior, they include the following:

1) subterranean cutworms, such as the pale western cutworm (Agrotis orthogonia), that feed almost entirely below the soil surface on roots and underground stems;

2) tunnel dwellers such as the black cutworm (Agrotis ipsilon), which cuts a tender plant at the soil surface, pulls it into the tunnel and devours the plant;

3) surface feeders such as the granulate cutworm (Feltia subterranea) and the army cutworm (Euxoa auxiliaris); and

4) climbing cutworms such as the variegated cutworm (Peridroma saucia), which can devour entire stands in early spring.

Most species of cutworms overwinter in the larval stage. After emerging from the pupa (cocoon), mated female moths deposit eggs that hatch into larvae (caterpillars) which develop through several larval stages (instars) before pupating in the soil. There may be three to five generations per year in central and south Texas, depending on weather conditions and temperature. The last generation of moths lay eggs in soil with suitable host plants, usually weeds. Fields that go into late fall or winter with weeds or cover crops are particularly attractive to cutworm moths.

Only the overwintering generation poses a threat to cotton. Partially grown larvae spend the winter months in the soil, feeding on weeds and grasses at night. In the spring when fields and plowed and planted, cutworms that were feeding on weeds and other host plants move to germinating seedlings. In field crops, damage usually appears as skips or sections of rows where all plants are missing.

Exceptions include the army cutworm, which overwinters in the mountains of west Texas in the adult stage and the variegated cutworm, which overwinters as pupae in the soil. Army cutworms can be very numerous during spring migrations and can be a nuisance when migrating moths invade buildings. Female army cutworm moths lay 1,000 to 3,000 eggs directly into soil. They seem to be attracted to bare areas such as over-grazed pastures, alfalfa stubble, stressed grassy areas, and newly planted or tilled crop-land. Some army cutworms that hatch in late fall overwinter as larvae in areas with mild winters. In locations where winter prevents larval development, migrations of moths from overwintering areas produce the first spring generation. Only larvae of the overwintering generation and the first

17 spring generation pose a threat to cotton. Variegated cutworm moths emerge from pupae in the soil when spring temperatures favor plant germination. They deposit eggs in batches on low stems and leaves, and larvae are often found on the soil surface, beneath leaves and other debris. Only the first spring generation poses a threat to cotton.

Fields in which a large number of leguminous plants or other broadleaf weeds are present at planting should be considered to be at extremely high risk of cutworm infestation. Cultural control includes keeping fields as weed free as possible 3 weeks before planting to minimize cutworm problems. In fields and locations with a history of cutworm problems, weeds and cover crops should be destroyed with tillage or herbicides at least 3 weeks before planting. Regardless of whether or not a cutworm treatment is applied at planting, fields of seedling cotton should be scouted regularly for cutworms until plants reach the four to five leaf stage, at which point the plants become relatively safe from cutworm damage.

Insecticides banded over the row at planting is recommended for fields in which significant populations of cutworms have been identified. If the ground is dry, cloddy or crusty at the time of treatment, control may not be as effective as in moist soil. The economic threshold for cutworms is somewhat subjective and often depends on other factors affecting the cotton stand. Treatment is recommended when cutworm infestations threaten to reduce plant population below an acceptable level (approximately 35,000 plants per acre). Because cutworms are relatively susceptible to the recommended insecticides, a single application is usually sufficient. It is worth noting that most of the treatments that are applied in-furrow, or as seed treatments, for thrips control do not provide effective cutworm control. Also, transgenic Bt cotton does not provide effective control of cutworms. This is because cutworms are relatively more tolerant of Bt toxin than many other caterpillar pests and because large cutworm larvae will destroy several plants before they consume enough toxin to provide control.

Aphids

Three species of aphids, or plant lice, feed on cotton plants: the cotton aphid (Aphis gossyppii), the cowpea aphid (A. craccivora) and the green peach aphid (Myzus persicae). The cotton aphid is the most common aphid found in cotton and the most likely to produce sever outbreaks. Other aphids are less common in cotton and are usually occasional pests. Outbreaks of the cotton aphid usually result from the secondary effects of insecticide applications. Synthetic pyrethroids are the insecticides most likely to produce aphid outbreaks. The other two species of aphids also are secondary pests and occur more sporadically.

Cotton aphids vary in color from light yellow to dark green to almost black. The immature or nymphal stage looks like the adult stage, only smaller. Most adults do not have wings. Cowpea aphids are shiny black with white patches on the legs and are common on seedling plants. Green peach aphids also have several color variants, ranging in color from red to pink and from pale yellow to green. The yellow to green variant is most common in cotton. Winged migrant forms have a yellowish- green abdomen with a dark dorsal blotch.

Aphid infestations occur throughout the growing season. In the Eastern, Southern, Blacklands and Trans Pecos regions of Texas early-season infestations are common. In the High Plains and Rolling Plains, early-season infestations are uncommon but occur occasionally. Mid- and late season outbreaks of the cotton aphid are more common. Several widespread outbreaks have produced severe losses to Texas cotton. In 1991, after catastrophic losses to cotton aphid outbreaks that could not be controlled with insecticides, the Texas A&M Cotton Aphid Task force was organized. The task force includes Research and Extension entomologists who provide guidelines for cotton aphid management.

18 Aphids usually are found on the undersides of leaves, on stems, in terminals and sometimes on fruit. Heavy and prolonged infestations can cause leaves to curl downward, older leaves to turn yellow and shed, squares and small bolls to shed and bolls to be reduced in size, resulting in incomplete fiber development. Honeydew excreted by aphids can drop on fibers of open bolls. A black, sooty fungus sometimes develops on the honeydew deposits during wet periods. Fiber from such bolls is stained, sticky and of lower quality, resulting in difficult harvest, ginning and yarn spinning. Natural control by unfavorable weather, predators, parasites and pathogens can be effective in holding populations below damaging levels. Sometimes aphid numbers increase to moderate or heavy levels and then decline for no apparent reason.

Aphid management and decision making. Although high populations can develop prior to bloom, most economically damaging infestations develop later in the season during the blooming period. Fields should be scouted twice per week since rapid increases in aphid numbers can occur in a short time. A total of 60 leaves divided between the top, middle and lower portion of the plant should be sampled from plants across the field to determine infestation levels. Insecticidal control of cotton aphids should be delayed until infestations exceed 50 aphids per leaf.

After severe losses to cotton aphids in 1990 and 1991, the Texas A&M Cotton Aphid Task force was organized with Research and Extension entomologists to provide guidelines for cotton aphid management. Recognizing the potential for insecticide resistance in aphids, insecticide use must be developed with a "resistance management" strategy. For cotton production, the task force suggested the management practices listed below.

! Optimize planting date to escape times of the year with high aphid populations. Plant to ensure an adequate and uniform stand

! Avoid excessive nitrogen by fertilizing based on soil test

! Minimize the use of (nerve-active) insecticides early in the season, particularly aphicides (dicrotophos, methomyl and chlorpyrifos on cotton). NOTE: Since the cotton aphid has the ability to develop resistance to all classes of insecticides, maintaining effective insecticides through conservative use, rather than alternating insecticide classes, appears to be the most valuable approach. Delay insecticidal control of aphids until aphids exceed economic threshold levels (50 aphids/leaf).

! Use higher labeled rates of effective insecticides for aphid control. When pyrethroids are applied for other pests an aphicide may be added. Maximize insecticide coverage on lower plant parts.

Grasshoppers

In the tall grass prairie and coastal prairie production regions of Eastern, Southern and Blacklands production regions, several grasshopper species, particularly the plains lubber grasshopper (Brachystola magna), the differential grasshopper (Melanoplus differentialis), the redlegged grasshopper (M. femurrubrum) and Packard grasshopper (M. packardii) are occasional pests of early-season cotton.

The grasshopper most often identified with early-season damage is the Plains lubber grasshopper. However, the other species may also combine in damaging aggregations. They often migrate to cotton fields from adjacent roadsides, fencelines and rangeland where they have built up during previous seasons. They usually appear suddenly in migrating swarms following early spring periods of rainfall that favor egg development followed by periods of dry later spring weather that favor egg hatching. Outbreaks are usually local in nature but may involve several hundred to several thousand acres. They usually move into

19 fields from adjacent hatching areas in fence rows, ditch banks and field margins after they have exhausted food supplies, which consist primarily of annual broadleaf weeds. Grasshopper management in the Eastern, Southern and Blacklands areas begins with early-season scouting of fields. Suggested treatment levels have been reached when twenty or more grasshoppers per square yard in crop margins or 10 or more per 3 row feet in cotton fields are found, and there are signs that the species is feeding on cotton.

In the arid shortgrass prairies of the high plains and rolling plains and the desert ranges of the Trans Pecos, outbreaks of the plains lubber grasshopper are most often involved in destruction of early-season cotton. The plains lubber grasshopper is a large, brown, clumsy grasshopper without fully developed wings. It cannot fly but its hind legs are greatly enlarged and it is a strong hopper. It can be extremely damaging to seedling cotton. Large numbers are capable of completely destroying stands, especially around field margins.

Grasshopper management and decision making. Although no economic threshold has been established for this species, field observations have indicated that populations of one per 3 row feet in the field or two per square yard in vegetation around the field may be capable of causing economic damage. Other species. A number of other grasshopper species are occasional cotton pests. They generally move into fields from adjacent fence rows, ditch banks or field margins.

Management and decision making. Damaging infestations need to be controlled early while grasshoppers are small and still in crop border areas. Twenty or more grasshoppers per square yard in crop margins or 10 or more per 3 row feet in the field are suggested treatment levels.

Whiteflies

Whiteflies (Bemisia spp.) are pests of cotton only in the Lower Rio Grande Valley, where subtropical climate, year-round growing conditions, and an abundance of host plants produce conditions conducive to maintenance and potentially high population growth rates of these pests. Silverleaf whitefly (Bemisia argentifolii) formerly known as sweetpotato whitefly (Bemisia tabaci), has been a pest of cotton in the Lower Rio Grande Valley since 1990. Its life cycle begins as a yellow-orange, cigar-shaped egg laid on end in groups or clusters usually on the undersides of leaves. A small, nearly clear crawler stage emerges from the egg, finds a suitable place on the leaf, and inserts its proboscis into the tissue and begins to feed. The scale-like immature stages continue to feed, molt and grow as immobile insects until they emerge as adults. The entire life cycle of the silverleaf whitefly lasts from 12 to 30 days, or longer, depending on temperature.

On cotton, in the heat of the summer, silverleaf whitefly can complete its life cycle in about 2 weeks. Because of its short life cycle and a high reproductive rate, silverleaf whitefly can build large populations over a relatively short period. Damage by silverleaf whitefly can reduce yield quality and quantity. Damage ranges from honeydew deposits on open cotton lint, to reduced plant vigor and premature defoliation. Experience in the Lower Rio Grande Valley has shown that in the heaviest infestations, yield reductions can be severe with losses of more than 500 pounds of lint per acre. Viral disease transmitted to cotton by silverleaf whitefly has been a severe problem in some countries, but has not been a problem in Texas.

Whitefly management and decision making. Sampling for silverleaf whitefly is generally conducted by examining the underside of the third leaf from the top of the plant and counting adults, and/or counting immatures on the underside of the fifth leaf from the top. Currently, thresholds for whitefly treatment in cotton are not set. However, adult silverleaf whitefly populations that have been observed to cause damage have ranged from 5 to 15 adults per leaf. Immature populations of 1 per square inch maintained for at least 6 weeks have been shown to cause yield losses of approximately 20 pounds per acre.

20 Cultural controls have provided one of the best approaches to silverleaf whitefly management in the Lower Rio Grande Valley and form the foundation for effective integrated management of this pest. Management of silverleaf whitefly in cotton actually starts with winter and spring vegetables and planting of the cotton. Winter and spring vegetables provide the largest source of silverleaf whitefly populations infesting cotton. Management of the pest on these crops and separation of cotton from these source populations play key roles in reducing potential problems in cotton. Timely destruction of vegetable crop residue that harbors active silverleaf whitefly populations is one of the simplest methods of lowering potential levels of silverleaf whitefly infestations in nearby cotton fields.

Host plant resistance is another key element of managing silverleaf whitefly in cotton. In general, smooth-leafed varieties have far fewer whiteflies than hairy-leafed cotton varieties. Yield data from tests conducted in the Lower Rio Grande Valley show that higher yields can be achieved if smooth-leafed varieties are grown when silverleaf whitefly are a threat to the crop.

Several species of naturally occurring parasites and predators will attack silverleaf whitefly and can aid in the management of infestations. However, these beneficials must be preserved to have maximum impact on silverleaf whitefly populations. Applications of broad spectrum insecticides decrease the role of beneficial insects in managing silverleaf whitefly. The impact of beneficials also can be easily overwhelmed by the presence of a large source population nearby.

Tests conducted in the Lower Rio Grande Valley during the last several years have shown that insecticidal control of silverleaf whitefly populations is achievable, but is most efficacious and cost effective when used as part of an integrated management program. Insecticides alone have been found to be ineffective, or cost prohibitive, when populations are large and other management strategies are not being employed. Insecticidal control is not an effective stand alone strategy for management of this pest.

Saltmarsh caterpillar (Estigmine acrea)

Saltmarsh caterpillars may attack cotton plants from the seedling stage to the fully mature crop stage. Generally, the larval stages will migrate into a cotton field from surrounding vegetation such as wild sunflowers. Some adults may emerge from within the cotton field and lay eggs in large (1 to 2 inches in diameter) clusters of cream colored masses on individual leaves. The young caterpillars will disperse from their places of hatching and spread out across the field. Some individual fields may be severely defoliated. But usually only margins of fields are attacked and little economic damage is done. Spraying for large infestations of saltmarsh caterpillars is best conducted only when the larvae are very small and more easily controlled. Once larvae reach the 1- to 2-inch stage, they are much more difficult to control. No established thresholds exist for saltmarsh caterpillars. Producers should use their best judgment about the extent of actual crop damage when determining if control is necessary.

Other early-season foliage-feeding pests

Garden webworms (Achyra rantalis), several species of armyworms, and cotton square borers are occasional early-season pests of cotton in the High Plains, Rolling Plains and Trans Pecos regions. Garden webworms can be a problem on cotton seedlings to the 6-leaf-stage. High numbers of beet armyworms (Spodoptera exigua), yellowstriped armyworms (Spodoptera ornithogalli) and saltmarsh caterpillars (Estigmene acrea) can reduce plant stands. Treatment of isolated areas within a field or along field borders can be effective in controlling these pests and reducing their spread across the field.

21 Early-season square-destroying pests

Cotton Fleahopper (Pseudatomoscelis seriatus)

Adult fleahoppers are about 1/8 inch long and pale green. Nymphs resemble adults but lack wings and are light green. They move very rapidly when disturbed. Adults move into cotton from weed hosts when cotton begins to square. Both adults and nymphs suck sap from the tender portions of the plant, including small squares. Squares are susceptible to damage from the pinhead size through the 1/3-grown stage.

The decision to apply insecticide should be based on the number of fleahoppers present, the squaring rate and the percent square set. If conditions are conducive to the rapid build up of cotton fleahoppers in alternate hosts, scouting intervals must be shortened to avoid damage from sudden migrations. In the Lower Rio Grande Valley, 15 to 25 cotton fleahoppers (nymphs and adults) per 100 terminals during the first 3 weeks of squaring may cause economic damage. After the first three weeks, as plants increase in size and fruit load, larger populations of fleahoppers seldom produce economic yield reduction. In the Blackland area, 10 to 15 fleahoppers per 100 terminals may cause economic damage during the first 3 weeks of squaring. In Eastern and Southern other areas of Texas, 15 to 25 fleahoppers per 100 terminals is considered economically damaging. In the High Plains, Rolling Plains and Trans Pecos regions, the economic threshold is 25 to 30 cotton fleahoppers per 100 terminals combined with less than 90 percent square set during the first week of squaring. In the second week of squaring, the economic threshold is 25 to 30 cotton fleahoppers per 100 terminals combined with less than 85 percent square set. Starting with the third week of squaring up to first bloom, the economic threshold is 25 to 30 cotton fleahoppers per 100 terminals combined with less than 75 percent square set. As plants increase in size and fruit load, larger numbers of fleahoppers may be tolerated without yield reduction. When plants are blooming, fleahopper control is rarely justified.

In the Eastern, Southern and Blacklands areas, fleahopper control is rarely justified after plants have started to bloom, and insecticides applied early in the blooming period may destroy natural enemies and cause outbreaks of bollworms and tobacco budworms. In the High Plains and Rolling Plains, treatment decisions for cotton planted after May 15 should be made during the first week of squaring, if possible, to avoid a potential bollworm outbreak resulting from the destruction of beneficial insects and spiders. In most years treatment is rarely justified after first bloom. However, occasionally, when cotton plants do not set an adequate square load during the first 3 weeks of squaring, fleahoppers can prevent the square set that is needed for an adequate crop. The use of higher application rates is suggested only when infestations are severe.

Boll Weevil (Anthonomis grandis)

Of the key pests of cotton, the boll weevil, Anthonomus grandis Boheman, has historically proven to be one of the most costly and difficult to control. A native of Mexico and Central America, the boll weevil was first introduced into the United States near in the Lower Rio Grande Valley of Texas. It was first identified from specimens taken near Brownsville, Texas, in about 1892. By 1922, the pest had spread into cotton growing areas of the United States from the eastern two-thirds of Texas and Oklahoma to the Atlantic Ocean (Fig. 2). The boll weevil colonized northern and western portions of Texas during a subsequent range expansion that occurred between 1953 and 1966. By 1981, the insect was well established in parts of California, northwestern Mexico and Arizona. In the late 1980s, it was reported in the upper Rio Grande Valley of El Paso and Hudspeth Counties where it had spread from fields across the river in Chihuahua, Mexico.

As early as 1895 the tremendous damage caused by the boll weevil was recognized. Recommendations were made to terminate cotton production in the infested region and to

22 establish and maintain a cotton-free zone along the Rio Grande River bordering Mexico. In 1903 the Texas Legislature offered a $50,000 cash reward for a practical way to control the boll weevil. In 1904, after exhaustive attempts to eradicate boll weevils, entomologists concluded the boll weevil could not possibly be eradicated. Since that time, numerous methods of control have been tested and reported.

Fig. 2. Boll weevil in the U.S. (1892 - 1966).

From 1917 until the late 1940s, the most effective method of control was the use of short-season, early maturing cotton varieties and dusting with calcium arsenate. After World War II, DDT and other chlorinated hydrocarbons were used against boll weevil and many other pests until resistance eliminated their use in the mid-1950s. With reports of boll weevil resistance to organochlorines in 1955, applications of organophosphate insecticides became widespread.

In 1959 researchers discovered that the boll weevil enters diapause during late summer and early fall in ground trash to overcome the absence of host plants and cold winters, and in that year insecticide applications late in the season were made, as the cotton crop approached maturity, to destroy diapausing weevils before they entered hibernation sites. The size of emerging spring populations during the subsequent planting season was greatly reduced. In 1964 researchers found that temperature and photoperiod are key environmental factors controlling the onset of diapause in boll weevils, and in that year widespread applications of ULV malathion began in parts of West Texas to control boll weevils entering diapause. Continued research in 1973 research revealed that 50 to 100 percent of adult weevils had entered diapause as true cutout of the cotton crop approached. A diapause control program aimed at boll weevils was timed to that event. Although reports of boll weevil resistance to organophosphate insecticides began coming from Central America as early as 1968, it has not yet developed resistance in the United States, even in the Texas High Plains, where organophosphates have been used in an ongoing diapause program since 1964.

The boll weevil's high reproductive capability and the location of the developmental stages of the weevil inside the cotton fruiting structures allow this insect to build up to large populations quickly The boll weevil is a greater problem in areas where the eradication program has just begun or where it is in its early stages. In the Lower Rio Grande Valley, the

23 subtropical climate, favorable overwintering habitats and alternate hosts, all favor boll weevil survival. In other locations, wooded areas with heavy leaf litter provide favorable overwintering sites in cotton growing areas. In the northern and western cotton production regions, colder winter temperatures, arid and semiarid brush and rangeland provide less favorable overwintering habitats and cause high mortality of overwintering boll weevil. Control strategies for overwintering and in-season boll weevils are similar throughout Texas but differ significantly from one region to another for diapausing adults. When boll weevil populations reach economic damaging levels, insecticides are the primary control measure.

About $70 million is spent annually to control the boll weevil, but the pest still causes an estimated $200 million in crop losses each year. In recent years, these figures may have increased by 50 percent. A new control strategy is imperative because cotton cannot be grown profitably unless the weevil is controlled. Yield losses attributed to the boll weevil, the cost of insecticide control, environmental considerations, infestation of secondary insects and insect resistance all have resulted in an aggressive effort to develop a beltwide strategy for controlling the boll weevil in the United States.

Although most growers judiciously apply control measures to boll weevil infested acreage, in almost all such areas 5 percent to 20 percent of the infested acreage may receive inadequate or no control treatments. This uncontrolled acreage harbors populations capable of reinfesting neighboring areas. Models demonstrate that if only 10 percent of a population remains untreated in an infested area, that portion of the population can develop normally and redistribute throughout the surrounding area after only four generations, or less than one growing season. Also, judicious application of control measures cannot protect against reinfestation from neighboring areas the next season. Growers who treat their acreage are faced with a continuing need to apply insecticide to control reinfestations.

Boll weevil eradication

In spite of serious difficulties in the control of boll weevils, the idea of eradication has always had advocates. However, the tools necessary to initiate eradication did not become available until the 1960s. In 1966 research showed conclusively that the male boll weevil produces a wind-borne sex attractant pheromone. It was found that this pheromone was released by adult beetles soon after they entered cotton and began feeding. The pheromone not only attracted females, it also acted as an aggregation pheromone for individuals of both sexes (primarily in early and late season). By the 1972, refinements in pheromone chemistry elucidated and permitted synthesis of kilogram quantities of the four-component pheromone system of boll weevils. Accompanying the development of the synthetic pheromone was the development of the daylight fluorescent-yellow plastic Leggett trap, a nonsticky trap that uses the behavior patterns of the boll weevil to ensure efficient capture.

Based on the success of two experimental eradication experiments in southern Mississippi, parts of Louisiana and Alabama, and in North Carolina and Virginia, the southwestern and southeastern boll weevil eradication programs were created. In 1978, an eradication program for the boll weevil began which continues today. The program includes the following four components:

1. Area-wide insecticide treatment of cotton for overwintered boll weevils at first pin-head square stage in the spring, 2. In-season control using insecticides, 3. Reproduction-diapause control in early and late season to reduce the numbers of weevils entering cotton fields each spring, and 4. Survey and monitoring with pheromone-baited traps.

The Southwest Boll Weevil Eradication Program was implemented in 1985 to eradicate the boll weevil from about 233,000 acres in western Arizona, southern California and northwest

24 Mexico. In 1988, the program expanded to include 320,000 acres of cotton in central Arizona. Eradication in southern California and western Arizona was completed in 1987, and in 1991 in central Arizona. After boll weevil was identified in the Upper Rio Grande Valley of Texas (El Paso and Hudspeth counties), this area of the Trans Pecos region was added to the central Arizona eradication program. By 1991, the boll weevil was declared eradicated in far west Texas.

Fig. 3. Boll weevil eradication program (2004).

The statewide eradication of boll weevils in Texas began in 1993, with the establishment of the Texas Boll Weevil Eradication Foundation, Inc. by the Texas Legislature in 1993. This was the most ambitious of the eradication programs, extending eradication over more than 6 million acres. The cotton-producer run, nonprofit foundation governs and oversees the implementation of the boll weevil eradication program in Texas. For the 2002 growing season, 11 zones, representing about 6 millions acres of cotton, will be active in the eradication program (Fig. 3).

The Southern Rolling Plains zone was the first area to start the program on 220,000 acres in the fall of 1994, and was declared functionally eradicated, the first zone to achieve eradication, in September 2000. The Rolling Plains Central zone was declared functionally eradicated in February 2002.

Overwintered boll weevil management strategy

Lower Rio Grande Valley

The boll weevil becomes active in the Lower Rio Grande Valley earlier than in any other cotton production area in Texas. Overwintered boll weevils emerge from winter hibernation sites and enter cotton early in the season. They occur in very low numbers and females do not lay eggs until first squares are about 1/4-inch in diameter (1/3-grown). The overwintered weevil is about 1/4-inch long, grayish brown, and has a prolonged snout with chewing mouthparts at its tip. The presence of two distinct spurs on the lower part of the first segment of the front leg will distinguish the boll weevil from other weevils with which it might be confused.

Insecticides applied at this time suppress boll weevil population buildup until after peak bloom. This allows the plant to set a large number of bolls early, while having little adverse

25 effect on mid- and late-season beneficial insects. The value of making automatic insecticide applications for overwintered weevils has not been demonstrated in all areas of the Lower Rio Grande Valley. Research has shown that 40 overwintered boll weevils per acre can produce a damaging first generation population. The first generation of boll weevils emerges and becomes active during the early fruiting period.

The primary control of overwintering boll weevils entering cotton fields is the application of pesticides. With the initiation of boll weevil eradication in the Lower Rio Grande Valley, insecticides are applied automatically with the appearance of overwintered boll weevils in fields. This now occurs regardless of whether or not economic infestations have occurred, particularly in fields bordered by wooded or brushy areas that serve as overwintering habitats. Since the start of the eradication program, nearly 100% of boll weevil control applications are initiated by the Texas Boll Weevil Eradication Foundation. Only a few instances of infestation still require producers to apply boll weevil insecticides.

If weevils are noticed and the field has a history of heavy weevil infestation, early-season control applications are justified. The first application should be applied no earlier than ¼-grown squares. The second application should be applied 3 to 5 days later if weevils continue moving into the field.

When two early-season applications of insecticides were made in research and field tests, damaging boll weevil levels were delayed 10 to 12 days in fields where weevils were heavy. However, in other areas where similar spray tests were conducted, subsequent damaging weevil levels were not delayed because of unknown factors. These applications should not be made in fields where population buildup in past years has not occur-red and weevils are not found. Avoid making the final overwintered boll weevil insecticide application within 10 days of bloom to allow beneficial insect and spider populations time to reestablish in anticipation of bollworm infestations.

Eastern, Southern and Blacklands

In the Eastern, Southern and Blacklands regions of Texas, overwintered boll weevils emerge from winter hibernation sites and enter cotton early. Although somewhat later in the year than the Lower Rio Grande Valley, it corresponds to phenological development stages of cotton in the planting season for these areas. Overwintered boll weevils generally occur in very low numbers and females lay few eggs until first squares are about 1/4 inch in diameter (1/3-grown). Insecticides applied at this time (see control suggestions) will help suppress boll weevil population buildup until after peak bloom. In many years this allows the plant to set a large number of bolls early, while having little adverse effect on mid- and late-season beneficial insects.

The primary control of overwintering boll weevils entering cotton fields is the application of pesticides. All of these regions are under boll weevil eradication programs. Insecticides are applied automatically applied with the appearance of overwintered boll weevils in fields, particularly those bordered by wooded or brushy areas, which serve as overwintering habitats. Since the initiation of eradication programs in these regions, nearly 100% of all boll weevil control applications are initiated by the Texas Boll Weevil Eradication Foundation. Only a few areas still require producer-applied boll weevil insecticides. The need for cotton producers to apply insecticides to suppress overwintered boll weevils is determined by any one of the three following criteria:

1) pheromone trap collections (see Table 1. Boll weevil trap index),

2) field scouting results, and

3) the history of the field.

26 Boll weevil trap index. Six to eight pheromone traps are required for a field of 50 to 300 acres. Traps should be evenly spaced around the field margin. The treatment decision is based on the "Trap Index" (TI) and scouting information. The TI is calculated by averaging the number of weevils captured per trap each week, then adding these averages together for the 6 weeks prior to the first 1/3-grown square stage. The Trap Indexes (TIs) in Table 1 were developed using the Hardee trap, and can be used for making treatment decisions.

Management decisions for overwintered boll weevils in the Eastern, Southern and Blacklands areas must be taken in fields where at least one weevil is found by the 1/3-grown-square stage, where pheromone trap results indicate the need for treatment, and/or where the field has a history of boll weevil infestations. These early applications should not be made in fields far from overwintering sites or where population buildup in past years has not occurred. As the plant develops and match head-sized (3/16-inch diameter) squares are present, the field should be scouted for the presence of adult boll weevils.

Table 1. Boll weevil trap index and treatment decisions Trap Index Decision Fewer than 1 weevil/trap Do not treat. 1 to 2.4 weevils/trap Do not treat unless damage and/or adult weevils are found. More than 2.4 weevils/trap Treat just before first 1/3-grown square and again 4 or 5 days later. A third application may be necessary in some fields.

Inspect at least 100 plants in the portion of the field where plants are largest and/or nearest to overwintering habitats. If a single boll weevil is found, the economic threshold level has been reached, and an insecticide should be applied to prevent egg laying. Where possible, band insecticides over the row. The second application should be made 4 to 5 days after the first. Do not make this application within 10 days of bloom to allow beneficial insect and spider populations time to reestablish in anticipation of bollworm infestations. There is always a risk of increased bollworm activity after these treatments.

High Plains, Rolling Plains and Trans-Pecos

Overwintered boll weevils emerge later in the year in the High Plains, Rolling Plains and Trans Pecos regions than any other regions of Texas. The Rolling Plains is only slightly later than the Northern Blacklands. Emerging overwintered boll weevils usually move relatively short distances from hibernation sites and usually are confined to small areas in fields adjacent to good overwintering habitat. Overwintered weevil emergence begins during early spring and generally peaks during late May and early June. However, significant emergence can continue into early July in some years. The adult weevil is about 1/4 inch long, grayish brown, and has a prolonged snout with chewing mouthparts at its tip. The presence of two distinct spurs on the lower part of the first segment of the front leg will distinguish the boll weevil from other weevils with which it might be confused.

Weevil colonization in cotton is closely related to the fruiting of the plant, with the greatest numbers of overwintered weevils entering cotton fields after squares are present. Therefore, the extent of overwintered weevil infestation depends on the size of the emerging weevil population and the availability of squaring cotton. Thus, early-planted cotton and fields adjacent to ideal overwintering habitat are much more likely to have significant weevil infestation than cotton planted later in the season or fields farther away from good overwintering habitat. In areas where a uniform delayed planting date is recommended, volunteer cotton should be destroyed as early as possible.

27 All of the cotton acreage in the High Plains, Trans Pecos and Rolling Plains is now in the boll weevil eradication program. If producers or others have questions about boll weevil control in their area, they should call the local Texas Boll Weevil Eradication Foundation office or contact the foundation at (325) 672-2800. However, producers should still follow good management practices to aid boll weevil eradication. In the Rolling Plains, uniform planting of cotton on a community wide basis after mid-May will often significantly reduce weevil infestations. When fruiting cotton is not available for feeding, the life span of newly emerged weevils is relatively short. Therefore, delayed, uniform planting of cotton increases suicidal emergence of overwintered weevils.

In addition, producers can help with eradication by doing the following:

1) Avoid planting cotton in small fields that are difficult to treat (such as those surrounded by trees or buildings, or occupied by people or livestock),

2) Make boll weevil eradication personnel aware of all cotton fields,

3) Provide boll weevil eradication personnel access to all cotton fields,

4) Assure that pheromone traps are kept standing and operational, and

5) Promptly alert eradication personnel of any field detections of live boll weevils or weevil-punctured squares.

Early-season plant bugs (Lygus and Creontiades spp.)

Lygus bugs

In the Eastern, Southern and Blacklands areas of Texas, Lygus bugs, primarily the tarnished plant bug (Lygus lineolaris) is one of several Lygus species that feeds on cotton terminals, squares and small bolls. Adults are winged, vary in color from greenish to brown, and are 1/4 inch long. Immature tarnished plant bugs (nymphs) are light green. Late instars have four conspicuous black spots on the thorax and one large black spot near the base of the abdomen. The nymph's wings are not developed, but nymphs can move rapidly and are difficult to detect in cotton foliage. Small nymphs may be distinguished from aphids by their rapid movement. However, they may be confused with cotton fleahoppers and leaf hopper nymphs.

In the High Plains, Rolling Plains and Trans Pecos regions of Texas, the western tarnished plant bug (Lygus hesperus) is one of several Lygus species that feeds on cotton terminals, squares and small bolls. Adults are 1/4 inch long, have a conspicuous triangle in the center of the back, are winged, and vary in color from pale green to yellowish brown with reddish brown to black markings. Nymphs move rapidly and are difficult to detect in cotton foliage. Small nymphs are similar to aphids in color, shape and size but may be distinguished from aphids by their rapid movement. They may be confused with cotton fleahoppers and leaf hopper nymphs. The western tarnished plant bug prefers legumes to cotton and usually are found in large numbers in areas of alfalfa or potato production or areas providing wild hosts such as clovers, vetches, mustard and dock.

Eastern, Southern and Blacklands

In the Eastern, Southern and Blacklands production regions, Lygus bugs prefer legumes to cotton and usually are found in large numbers in areas of alfalfa production or areas providing wild hosts, such as clovers, vetches, mustard and dock. Lygus bugs are attracted to succulent growth. Their feeding results in shedding of squares and small bolls, stunted growth black anthers and puckered areas in petals.

28 The need for lygus bug control is determined by their abundance in relation to the fruiting condition of the cotton plants. Inspect fields at 4- to 5-day intervals during the first 6 weeks of squaring. Take 50 sweeps at each of the four locations in the field by sweeping a 15- to 16-inch net across the top of one row only in such a way that the top 10 inches of the plants are struck. During the first 6 weeks of squaring, control measures should be considered when lygus bug numbers average 10 (count nymphs as two) per 50 sweeps on more than two successive sampling dates (spaced 5 days apart).

High Plains, Rolling Plains and Trans Pecos

In the High Plains, Rolling Plains and Trans Pecos production regions, Lygus bugs are most often attracted to succulent growth from wild host plants or fields and pastures producing alfalfa, clover, vetch or potatoes. Lygus feeding results in shedding of squares and small bolls, stunted growth and boll deformation. Feeding damage to small bolls is often characterized as small black spots or small, sunken lesions. The feeding that causes these spots or lesions may or may not penetrate the boll wall and damage developing seeds or lint. Damage to blooms appears as black anthers and puckered areas in petals.

The need for lygus bug control is determined by their abundance in relation to the fruiting condition of the cotton plants. Fields should be inspected for lygus bugs at 4- to 5-day intervals using a drop cloth (see discussion on page 7). During the first week of squaring, the economic threshold is one lygus bug adult or nymph per 3 feet of row combined with less than 90 percent square set. In the second week of squaring, the economic threshold is one lygus bug adult or nymph per 3 feet of row combined with less than 85 percent square set. In the third week of squaring, the economic threshold is one lygus bug adult or nymph per 3 feet of row combined with less than 75 percent square set. After the third week of squaring, the economic threshold is two lygus bug adults or nymphs per 3 feet of row with less than acceptable fruit retention. Research indicates that the western tarnished plant bug (Lygus hesperus) may be more difficult to control with insecticides than other plant bugs and may require the use of higher labeled rates of labeled insecticides.

Creontiades spp. Lower Rio Grande Valley

Plant bugs, a general term for insects in the family Miridae, feed on cotton terminals, squares and small bolls. Creontiades spp. is a plant bug that has become more common in the lower Rio Grande Valley. Creontiades species found in the Lower Rio Grande Valley are small (1/4 inch in length), narrow bodied, yellow-green plant bugs. The insect goes through several molts or instars (nymphs).

The smallest nymphs are about the size of a large cotton fleahopper nymph, with similar rapid movement around the plant structures. Differences between Creontiades species and cotton fleahoppers exist that make identification easier. Cotton fleahopper nymphs have red eyes and both adult and nymphal stages of cotton fleahoppers have bar marks on the antennae. Creontiades nymphs do not have red eyes, have a reddish band on the rear of the pronotum and no bars or similar markings on their antennae. As a general rule, the adult male Creontiades is slightly darker green in color than the female.

Damage from Creontiades species in cotton can be square and small boll loss. A characteristic clear yellow liquid (Creontiades spp. frass) is often left on the fruiting structure where Creontiades have fed. Squares and small bolls may suffer damage ranging from just surface feeding and boll malformation to complete fruit loss.

Creontiades plant bug management and decision making. The need for plant bug control is determined by the insect abundance in relation to the fruiting condition of the cotton plants. Inspect fields at 4- to 5-day intervals during the fruiting period. Take 50 sweeps at each of the four locations in the field by sweeping a 15- to 16-inch net across the top of one row in

29 such a way that the top 10 inches of the plants are struck. Begin treatment when plant bug counts exceed 20 to 30 per 50 sweeps in fields where plants failed to retain squares and set bolls normally during the first 4 to 5 weeks of fruiting.

Early-season stink bugs

Eastern, Southern and Blacklands

Several species of stink bugs feed on squares and bolls in the Eastern, Southern and Blacklands areas. Species of stink bugs regularly causing losses of cotton in these regions include the green stink bug (Acrosternum hilare),southern green stink bug (Nezara viridula), brown stink bug (Euschistus servus), harlequin bug (Murgantia histrionica),rice stink bug (Oebalus pugnax), spined shouldered stink bug, (Podisus maculiventris) and several others occasionally contribute to early season yield reduction. Feeding by stink bugs on early- season fruiting forms may cause abortion of squares and shedding of small bolls. Loss of early season fruiting forms can produce significant yield reductions, delayed fruiting, increased exposure to hazards from mid- to late-season and delayed harvest of late maturing cotton.

Stink bug management and decision making in the Eastern, Southern and Blacklands regions. Examine 6 row feet of cotton in several locations in the field. When there is an average of one or more stink bugs per 6 feet of row, feeding can cause excessive loss of squares and small bolls and may stain lint. Additionally, at least 50 small bolls (the diameter of a quarter) should be examined. If 20 percent of the small bolls have evidence of internal feeding (callous growth on internal boll wall and/or stained lint) and stink bugs are present then treatment should be considered. Stink bugs often are clumped near field margins. Spot treatment provides effective control when this situation exists. Second through fifth instar stink bug nymphs and adults can damage bolls. Fourth and fifth instars can cause the same level of damage as adults.

High Plains, Rolling Plains and Trans Pecos

Two types of stink bugs may cause damage to cotton in the High Plains, Rolling Plains and Trans Pecos areas. The first type include stink bugs that prefer cotton and related plants as hosts and readily lay eggs in cotton fields. These include the southern green stink bug (Nezara viridula), brown stink bug (Euschistus servus), harlequin bug (Murgantia histrionica), spined shouldered stink bug, (Podisus maculiventris) and several others. The second type are opportunistic feeders that prefer other plants as hosts but migrate to cotton fields when preferred host plants become scarce. Species in this group rarely lay eggs in cotton fields. Stink bugs in this group include the conchuela stink bug (Chlorochroa ligata), Say’s stink bug (Chlorochroa sayi), consperse stink bug (Euschistus conspersus), western brown stink bug (E. impictiventris) and several others. Many of these stink bugs prefer sorghum, legume forages, Russian thistle or mesquite as hosts. They only move to cotton when maturing seeds from preferred hosts become too hard and dry for feeding or when crops adjacent to cotton fields are harvested. Both types feed on squares and bolls. Feeding on bolls may cause boll shed, seed damage and lint staining.

Stink bug management and decision making in the High Plains, Rolling Plains and Trans Pecos regions includes scouting and identification of pests. Examine 6 row feet of cotton in several locations in the field. When there is an average of one or more stink bugs per 6 feet of row, feeding can cause excessive loss of squares and small bolls and may stain lint. Additionally, at least 50 small bolls (the diameter of a quarter) should be examined. If 20 percent of the small bolls have internal injury from stink bugs and stink bugs are present then treatment should be considered. Stink bugs often are clumped near field margins.

30 Mid-Season and Late-Season Pests

Mid-season is the 6-week fruiting period following the appearance of the first 1/4-inch diameter (1/3- grown) squares. The major concern during this period is ensuring adequate fruit set and preserving beneficial insect populations. Proper crop management and frequent field inspection for pests and beneficials can eliminate unnecessary insecticide applications. This procedure ensures adequate fruit set and preserves beneficial insects.

Late-season is the remainder of the production season when the major concern is boll protection. Heavy irrigation and high rates of fertilizer prolong cotton plant growth and increase the chance of late-season insect damage. Monitoring boll set may aid in making spray decisions in the late-season period. Boll protection is of primary concern as long as bolls which will be harvested are immature. Pima cotton bolls take considerably longer to mature than upland cotton, and boll protection must be maintained considerably later into the season.

Bollworms, tobacco budworms, boll weevils and pink bollworms are key insect pests in mid- and late-season. A major goal of a well-planned pest management program (although not always achieved) is to avoid having to treat for bollworms and tobacco budworms. Naturally occurring parasites and predators and certain weather conditions often suppress bollworm and budworm populations. For this reason, late-season chemical control of boll weevils is seldom advised, particularly if a satisfactory fruit set occurred during the first 30 days of blooming. Loss of squares to weevils and fleahoppers later in the season can often be tolerated to conserve bollworm predators and parasites. This is not true for pink bollworm. Pink bollworm populations often increase in proportion to the number of bolls present in the field. In the High Plains and Trans Pecos regions, heavy pink bollworm damage can occur suddenly from mid- to late-season from high populations in fields and migrations from adjacent fields. Where Pima cotton is produced, insecticidal control of pink bollworms often must take precedence over conservation of bollworm predators and parasites. Similarly, in fields of upland cotton where fruiting has been delayed, additional insecticide applications may be necessary to protect smaller, late-set bolls from both boll weevil and pink bollworm damage. In locations where cotton is to be picked instead of stripped, fewer boll weevil-damaged or pink bollworm-damaged bolls can be tolerated.

With widespread planting of Bt cotton and boll weevil eradication, the plant bug and stink bug complex are becoming increasingly troublesome. There are several reasons the bug complex has become more of a problem in recent years. First, successful eradication of the boll weevil, development and high adoption of Bt cotton, and emphasis on selective insecticide chemistry have resulted in fewer broad-spectrum insecticide applications, which provided incidental control of Lygus bugs. A second factor is a change in weed management practices. Reduced tillage and the planting of glyphosate tolerant varieties have changed the weed spectrum in and around cotton fields. Many of these weeds are hosts to Lygus bugs and stink bugs. In some areas, increased planting of soybeans, corn or legume forages have provided hosts for Lygus bugs and stink bugs that readily move into cotton later in the season as their former hosts mature and dry. Finally, an increased tolerance or resistance of plant bugs to commonly used insecticides can account for increased numbers of these pests in cotton fields.

Cotton bollworm and tobacco budworm

Bollworm and budworm management in conventional cotton

Bollworm and tobacco budworm larvae are similar in appearance and cause similar damage. Full-grown larvae are about one inch long and vary in color from pale green to pink or brownish to black, with longitudinal stripes along the back.

31 Tobacco budworm and bollworm moths are attracted to and lay eggs readily in cotton that is producing an abundance of new growth. Moths usually lay eggs singly on the tops of young, tender terminal leaves in the upper third of the plant. Eggs are pearly white to cream colored and about half the size of a pinhead. These should not be confused with looper eggs, which are flatter and usually laid singly on the undersides of leaves. Eggs hatch in 3 to 4 days, turning light brown before hatching. Young worms usually feed for a day or two on tender leaves, leaf buds and small squares in the plant terminal before moving down the plant to attack larger squares and bolls. When small worms are in the upper third of the plant, they are most vulnerable to control by insecticides and beneficial insects and spiders.

Sometimes moths deposit eggs on squares, bolls, stems and, in general, on lower parts of the plant. This may occur when cotton plants are stressed and making little new growth, or during periods of high temperature and low humidity. Detection of eggs and control of small worms are more difficult when eggs are deposited in these locations.

Budworms are less numerous than bollworms early in the season. In the Lower Rio Grande Valley, bollworms are usually more numerous than budworms until mid-July. In the Eastern, Southern and Blacklands areas, they rarely occur in damaging numbers until mid- to late-season. In the High Plains, Rolling Plains and Trans Pecos areas, budworms do not reach high numbers until mid-August or early September, and seldom reach damaging levels.

A major objective of a well-planned IPM program is to avoid having to treat for bollworm and tobacco budworm. Naturally occurring parasites, predators and, to a certain extent, weather conditions often suppress bollworm and budworm populations.

Budworms are generally more resistant to insecticides than bollworms. Once certain kinds of conventional insecticides are used to control bollworms and budworms, the percentage of budworms in the infestation increases with each additional application because of selection pressure. Aphids and other secondary pest infestations may increase following bollworm/budworm sprays, especially when pyrethroids are used.

In the Lower Rio Grande Valley, Eastern, Southern and Blacklands areas, fields should be carefully scouted at least once a week and twice weekly during peak periods of egg deposition. Eggs and newly hatched worms are usually found in the plant terminals and indicate possible outbreaks. Natural mortality agents such as weather and predators frequently control these stages before any damage occurs. Once worms reach + inch long, natural control factors are much less effective.

In the High Plains, Rolling Plains and Trans Pecos, cotton fields should be scouted carefully every 3 to 5 days during periods of predicted egg-laying activity. In fields with fewer than five squares per row foot (approximately 67,000 per acre), bollworm populations often collapse and cease to be a problem.

Eggs and newly hatched worms are usually found in the plant terminals and indicate possible outbreaks. Natural mortality agents such as weather and predators frequently control these pests before any damage occurs. Once worms have grown to larger than ½-inch long, natural and insecticidal control are less effective. Insecticides applied to control ½-inch long worms are only moderately effective.

Frequently, examination of the upper third (terminal) of the plant (leaves, stems, squares, blooms and bolls) for eggs and small larvae is all that is needed to make a sound management decision. However, moths sometimes deposit eggs on the fruit and stems lower on the plant. This may occur when cotton plants are stressed and making little new growth, or during periods of high temperatures and low humidity, which occur frequently in the High Plains, Rolling Plains and Trans Pecos regions. Detection of eggs and small worms

32 is more difficult when eggs are deposited throughout the plant. Also, as bollworm/ budworm larvae increase in size, they attack fruit lower on the plant. When eggs are being laid all over the plants or when 60 percent or more of the bolls are mature, whole plant counts should be used. Mature, unopened bolls are firm, cannot be dented when pressed between the thumb and forefinger, and cannot be cut easily with a sharp knife. Whole plant inspections are also necessary to detect larger larvae.

In the Lower Rio Grande Valley before bloom, prior to initial chemical application, the economic threshold is 15 to 25 percent damage to green squares. After bolls are present the economic threshold has been reached when worms are present and 8 to 10 percent of the green squares have been worm damaged. After initiation of insecticide applications, fields should be checked closely every 2 to 3 days following the first application. Treatment thresholds have been reached when bollworm eggs and 6 to 10 young worms are found per 100 terminals (3,000 to 5,000 young worms per acre) and 5 percent of the squares and small bolls have been injured by small bollworms and budworms. If control has not been obtained, another application will be necessary immediately.

In the Eastern, Southern and Blacklands areas, insecticide application before first bloom may be justified when 15 to 25 percent of the green squares are worm damaged. Once blooms are present, an insecticide application may be justified when 8 to 12 or more small larvae are present per 100 plant terminals and 5 to 15 percent of the squares or bolls are worm damaged. If worm numbers are high, it may not be appropriate to wait until the damage threshold of 5 to 15 percent square damage is reached. If previous insecticide applications have eliminated natural enemies, fewer bollworms/tobacco budworms can be tolerated before economic damage occurs. If insecticides have been applied after first bloom and natural enemies eliminated, treatment may be justified when infestations reach or exceed four to five small worms per 100 terminals, eggs are present, and 5 percent of the squares and small bolls have been damaged by worms.

Microbial insecticides may be considered during the squaring period through the first 10 days of blooming if infestations average 12 or fewer small (less than 1/4 inch) bollworms per 100 terminals. Unlike conventional insecticides, microbial insecticides do not destroy predators and parasites (see Microbial Insecticides).

In the High Plains, Rolling Plains and Trans Pecos regions, the decision to apply conventional insecticides before bloom to control bollworm and budworm (as opposed to microbial insecticides, ovicides or no treatment) should be made very carefully. Conventional insecticides often kill beneficial insects and spiders, thus allowing a rapid resurgence in bollworm numbers. Avoid making conventional insecticide treatments on the basis of egg numbers or first signs of crop damage. Under most conditions, do not use conventional insecticides before blooms are observed in the field. Treatment may be warranted where 15 to 25 percent of the green squares examined are worm damaged and small worms are present. Microbial insecticide applications may be considered to preserve beneficial insects and spiders (see Microbial Insecticides). After bolls are present.

Research and Extension entomologists have established a range of treatment thresholds for both terminal and whole plant inspection methods in the different regions of Texas. This is because many factors together with density of larvae determine the need to apply insecticides. One of these factors is the number of predatory that feed on bollworm/budworm eggs and small larvae. If previous insecticide treatments have eliminated these beneficial insects, then a lower treatment threshold should be considered. However, if two or more key bollworm predators are found for each small worm, control measures may not be needed or a microbial insecticide may be considered (see Microbial Insecticides).

In the Eastern, Southern and Blacklands areas, the number of bollworm/budworm eggs can also be considered along with worm densities in making treatment decisions. The treatment

33 threshold will also vary according to the ability of the individual scout to locate small larvae, the age structure of the infestation, the stage of crop growth, the percent fruit set, the cost of insecticide treatment, the duration of the infestation (1 to 2 weeks vs. 3 to 4 weeks), the type of production system (high input/high yield or low input/low yield) and the market value of the crop.

In the High Plains, Rolling Plains and Trans Pecos areas, treatment may be justified when counts average 5,000 or more small worms per acre. However, if two or more key predators are found for each small worm, control measures may not be needed or a microbial insecticide may be used. The actual treatment level will vary according to the ability of the individual scout to locate small larvae, the age structure of the infestation, maturity of the crop and crop value.

Bollworm and budworm management in Bt transgenic cotton

Research trials evaluating the cry1Ac gene in transgenic Bt (Bollgard®) cotton varieties have determined it to be highly effective against tobacco budworms. Transgenic Bt cotton varieties are also effective against the cotton bollworm, but under heavy pressure from this species insecticide treatment may be needed.

The entire plant should be searched for tobacco budworm and bollworm larvae and injury. A proper sample includes squares, white blooms, pink blooms, bloom tags and bolls. Scouting intervals should be reduced to 3 to 4 days during periods of increasing bollworm egg laying, especially during peak bloom. Treatment should not be triggered by the presence of eggs alone. Hatching larvae must first feed on the cotton plant to receive a toxic dose. Treatment with foliar insecticides for tobacco budworm or bollworm should be considered when 4,000 to 8,000 larvae per acre larger than 1/4 inch are present (based on a population of 40,000 to 60,000 plants/acre) or when 8 to 12 larvae larger than 1/4 inch per 100 plants are present and 5 to 15 percent of the squares or bolls are worm damaged.

As with non-Bt cotton, a range of treatment thresholds is provided since many factors in addition to density of larvae and square damage determine the need to treat Bt cotton with insecticides. Many of these factors are the same as those listed above for non-Bt cotton. As in non-Bt cotton, predators and parasites are very important in reducing the numbers of eggs and larvae and they complement the control provided by these varieties.

For resistance management, the use of a non-Bt cotton refuge is a requirement for planting Bt cotton and is an important component of resistance management. Although applications of biopesticides, such as spinosyns and macrocyclic lactones are permissible, effective resistance management practices make it inadvisable to apply microbial pesticides containing mixed Bt toxins to transgenic Bt cotton varieties.

Mid-season and Late-season boll weevil management strategy

Summer generations of boll weevils, sometimes called "in-season" boll weevils are those that emerged from squares during the current growing season. The first summer generation emerge from squares that were punctured by overwintering weevils. Summer generation adults differ significantly in appearance from overwintered boll weevils. Adults of summer generations reddish brown and shiny instead of being grayish brown and dull. Summer generations will infest squares and bolls so long as suitable host material is available. Infestations are possible until very late in the season. The summer generation adults will feed for about four to eight days after emergence before they mate and lay eggs. A mated female can lay an average of 100 eggs in her life span of about 30 days.

Generally, weevil numbers are declining throughout the state as a result of the statewide eradication program. This has affected the number of applications made for in-season boll

34 weevils. Applications have declined considerably since the start of boll weevil eradication and continue to decline with eradication progress. However, the number of applications for in-season boll weevils varies depending upon how long an eradication program has been in place. In such places as the Concho Valley of the Southern Rolling Plains and the Coastal Bend of South Texas, where boll weevil eradication programs have been in place for more than ten years, very few in-season applications are made to control boll weevils. In the Lower Rio Grande Valley, where eradication began in 2005, considerably more applications are made to control the summer generations.

The Lower Rio Grande Valley

In the Lower Rio Grande Valley, as boll weevils move into the edges of fields from overwintering sites, insecticide treatments may be effectively limited to treating along brush lines or corners where boll weevils are concentrating. By treating only those "hot spots," whole fields are not "sterilized" and beneficial insects can move back into these treated areas more quickly.

Randomly inspect 100 1/3-grown squares at weekly intervals from four or more representative locations in the field and from various portions of the plant. If boll weevil-damaged square levels reach 15 to 25 percent from the time of squaring to peak bloom, the economic threshold level has been reached and an insecticide application is necessary. Weevil populations may require repeated treatments at 5-day intervals. Under extremely heavy populations, it may be necessary to shorten application intervals to 3 days. If the proper cultural considerations have been made under the short-season production system, mid- to late-season insecticide applications may not be necessary.

Eastern, Southern and Blacklands

In the Eastern, Southern and Blacklands areas, boll weevil adults emerging from infested fields (in-season boll weevils) puncture squares or bolls both for feeding and egg laying. Egg-laying punctures can be distinguished from feeding punctures by the presence of a wart-like plug which the female places over the feeding site after she has deposited an egg in the cavity. The female deposits an average of 100 eggs during her life span of about 30 days.

Eggs hatch into larvae (grubs) within 3 to 5 days under midsummer conditions. Grubs transform into pupae within the square or boll in approximately 7 to 11 days. Adults emerge 3 to 5 days later. Recently emerged adults feed on squares or bolls for 4 to 8 days before laying eggs. The time required for development from egg to adult under summer field conditions averages 17 days, with a complete generation occurring in 21 to 25 days.

Punctured squares flare open and usually fall to the ground in about a week. Small bolls that are punctured may also fall to the ground, but larger bolls remain on the plant. When direct sunlight and hot, dry conditions cause fallen squares to dry out rapidly, large numbers of weevil larvae do not survive. Boll weevil populations reach the highest level late in the growing season. As cotton plants mature and the number of squares is reduced, the percentage of boll weevil-damaged squares becomes an unrealistic indicator of damage because boll weevils are competing for squares. As square numbers decrease, boll weevils may cause more damage to small bolls.

Management decisions are made using criteria similar to those for control of overwintering boll weevils (see overwintered boll weevil section above). Insecticides are applied before the first 1/4-inch diameter (1/3-grown) squares are present in the field. Later in the season, insecticide treatments occur at weekly intervals. Producers or scouts should inspect 100 squares that are at least 1/3-grown. Take squares from at least four representative locations in the field and from various portions of the plants. If 15 to 25 percent of the squares are

35 weevil-damaged from the time of squaring to peak bloom, the economic threshold level has been reached and insecticide application is necessary. It may be necessary to repeat applications at 5-day intervals, or at 3-day intervals if weevil population buildup is extremely heavy.

After peak bloom, if 60 percent or more of the bolls are at least 30 mm (1¼ inch) in diameter, higher rates of damaged squares can be tolerated. However, additional applications may be necessary to protect smaller bolls if they are to be harvested. Where economic weevil infestations are encountered, protect bolls until the last bolls expected to be harvested are 12 to 15 days old.

Fire ants are effective predators of boll weevil larvae and pupae, although they will not prevent adults from migrating into the field and laying eggs. Fire ants can be sampled by the beat bucket method. Insecticides usually are not needed for boll weevil control when an average of four or more fire ants is collected per 10 terminal samples.

High Plains, Rolling Plains and Trans Pecos

In the High Plains, Trans Pecos and Rolling Plains, recently emerged in-season adults feed on squares or bolls for 4 to 8 days before mating and laying eggs. Adult weevils puncture squares or bolls both for feeding and egg laying. Egg laying punctures can be distinguished from feeding punctures by the presence of a wartlike plug which the female places over the feeding site after she has deposited an egg in the cavity. The female deposits an average of 100 eggs during her life span of about 30 days.

Eggs hatch into larvae, or grubs, within 3 to 5 days under midsummer conditions. Grubs transform into pupae within the square or boll in approximately 7 to 11 days. Adults emerge 3 to 5 days later. The time required for development from egg to adult under summer field conditions averages 17 days, with a complete generation occurring in 21 to 25 days.

All of the cotton acreage in the High Plains, Trans Pecos and Rolling Plains is now in the boll weevil eradication program. Producers should continue monitoring the plants for boll weevils and boll weevil damage. If boll weevils or boll weevil damage is found, producers should contact their local Texas Boll Weevil Eradication Foundation office or contact the foundation at (325) 672-2800.

Punctured squares flare open and usually fall to the ground within a week. Small bolls that are punctured may also fall to the ground, but larger bolls remain on the plant. When direct sunlight and hot, dry conditions cause fallen squares to dry out rapidly, large numbers of weevil larvae do not survive.

Boll weevil populations reach the highest level late in the growing season. As cotton plants mature and the number of squares is reduced, the percentage of boll weevil-damaged squares becomes an unrealistic indicator of damage because boll weevils are competing for squares. As square numbers decrease, boll weevils may cause more damage to small bolls.

Pink Bollworm

The pink bollworm (Pectinophora gossypiella), is native to Asia and was originally reported in cotton samples from India in 1843. It has since spread to virtually all cotton-producing countries and may be the most destructive pest of cotton worldwide. The first record of pink bollworm in the United States is from 1917 in Hearne, Texas. By 1929, it had spread across western Texas, New Mexico and Arizona. It has since become an established major pest of cotton in the High Plains and Trans Pecos of Texas, New Mexico, Arizona and California. The pink bollworm prefers cotton but will also feed on Okra, Kenaf, Hibiscus and several weeds in the mallow family (Malvaceae).

36 Pink bollworms are primarily late-season insect pests. Larvae will feed on squares in the early season without economic damage to the crop. But once bolls are present, they become the preferred food supply. Pink bollworm larvae prefer 15- to 20-day-old upland cotton bolls. Pima cotton bolls remain susceptible to damage until they are 35 to 40 days old. It is essential that bolls set during the first 4 weeks of the boll-setting period be protected from pink bollworm damage. In Pima cotton it is important to protect the crop even longer, since it matures more slowly. To provide this protection normally requires continued scouting and treatments if necessary until mid-September for upland and the first of October on Pima.

Management and decision making for pink bollworm must be based on both pheromone trapping and field scouting. Pink bollworm pheromone traps should be placed in fields at seedling emergence and monitored at least weekly until the 4- to 5-leaf stage, then daily until the 1/3-grown square stage. If more than five moths are caught per trap per night at the pinhead square stage, insecticides or pheromone mating disruption products or a combination should be applied. Subsequent treatments may be needed if indicated by the trap catches. Terminate treatments prior to the 1/3-grown square stage.

In areas where moths are captured in pheromone traps, field inspections for rosetted blooms should be made after the crop is in the second week of bloom. Since rosetted blooms caused by pink bollworms do not result in economic damage, the rosetted bloom counts and pheromone trap data should be used for detection of infested fields and to time pheromone mating disruption sprays for population suppression. Generally, insecticide applications should be reserved for later in the season.

Pink bollworm management in conventional cotton

In management and decision making for pink bollworm, pheromone traps should be placed in fields at seedling emergence and monitored at least weekly until the 4- to 5-leaf stage, then daily until the 1/3-grown square stage. If more than five moths are caught per trap per night at the pinhead square stage, insecticides or pheromone mating disruption products or a combination should be applied. Subsequent treatments may be needed if indicated by the trap catches. Terminate treatments prior to the 1/3-grown square stage.

In areas where moths are captured in pheromone traps, field inspections for rosetted blooms should be made after the crop is in the second week of bloom. Since rosetted blooms caused by pink bollworms do not result in economic damage, the rosetted bloom counts and pheromone trap data should be used for detection of infested fields and to time pheromone mating disruption sprays for population suppression. Generally, insecticide applications should be reserved for later in the season.

Where rosetted blooms are detected in a field, inspections of 40 to 50 quarter-sized bolls should be made twice weekly. Collect bolls when walking diagonally across the field. Bolls should be cracked or cut and examined for the presence of pink bollworms. Examine the inside of the carpel wall for the entrance wart or mines made by small larvae, and the lint and seed for evidence of feeding or larvae. Pheromone traps can be helpful in identifying infested fields and timing insecticide applications, but should not be used without boll inspections as a decision-making tool. Oil trap catches of 60 to 100 moths per trap per night for three nights are a strong indicator that an adult flight is underway and treatment may be needed.

When weekly boll counts indicate a 10 to 15 percent infestation during the first 6 weeks of boll set in upland cotton, or 5 to 10 percent in Pima cotton, insecticide treatments are warranted. Apply insecticide treatments using pheromone trap catches as a timing indicator or apply on a 5-day schedule. Where infestations occur late in September, 40 to 50 percent of the top-crop bolls may be infested without economic loss in upland cotton.

37 Insecticide treatments for pink bollworm should be terminated in non-Bt upland cotton when the last bolls expected to be harvested are at least 30 days old. Newly hatched pink bollworm larvae have difficulty entering the more mature bolls and surviving in the dry fibers. Upland bolls 30 days old and older are sufficiently hard to withstand pink bollworm entry. In Pima cotton, treatments should be continued until 70 percent of the bolls are open. Pima bolls remain vulnerable to pink bollworms for at least 45 days after bloom, and later in the season, may remain vulnerable longer, particularly if late summer and early autumn weather is cool and rainy.

Cultural control is the most desirable, satisfactory and economical method of controlling pink bollworms. Farming practices should be planned and conducted for early crop maturity and to permit crop termination by mid-September. The pink bollworm is an occasional pest in the High and Rolling Plains areas.

Cotton should be harvested as early as possible. Stalks should be shredded and plowed (preferably with a moldboard) to a depth of at least 6 inches. Plowing should be completed as early as possible. By law, they must be plowed by February 1.

Pink bollworm management and Bt transgenic cotton

Since the release of Bt cotton varieties, tests show that Bt cotton has provided an exceptionally high level of season-long control of pink bollworm (Flint et al. 1995, Watson 1995, Henneberry et al. 2001, 2002, Marchosky et al. 2001, Dennehy et al. 2004). This high level of control has made the widespread planting of Bt cotton one of the basic elements of the national pink bollworm eradication program (El-Lissy and Staten 2005). Although expression of the Bt genes in transgenic cotton vary from very high to zero, infestation levels in Bt cotton fields usually remain below economically injurious levels throughout the season. Pesticide applications for pink bollworm in transgenic Bt cotton varieties is usually near zero.

Despite early concerns regarding potential development of PBW resistance to Bt cotton (Bartlett 1995, Watson 1995, Patin et al. 1999), evaluations from 1995 through 2000 of varieties of Bt cotton incorporating the Cry1Ac gene and its combinations with the Cry2Ab gene show that Bt cotton varieties continue to provide an exceptionally high degree of season-long efficacy against PBW, irrespective of the suggested reduction in the amount of toxic protein in fruit tissues late in the season (Henneberry et al. 2001).

Planting of the Bt transgenic cotton varieties is highly encouraged as they provide an exceptional level of control for pink bollworm. The program maintains full compliance with the Environmental Protection Agency's (EPA) Refuge Requirements, designed as a strategy for insect resistance management (IRM) (El-Lissy and Staten 2005).

To address pink bollworm (PBW) resistance to the Cry1Ac endotoxin expressed in Bollgard® and WideStrike® cotton varieties, three resistance management approaches are available in EPA's required IRM plan.

1) The pesticide option. For every 100 acres planted with Bt transgenic cotton with the Cr1Ac gene planted, producers must plant 25 acres of conventional cotton (i.e. without the Cry1Ac gene), which CAN be treated with insecticides (other than formulations containing Bt kurstaki) for the control of tobacco budworm, cotton bollworm and pink bollworm.

2) The non-pesticide option. every 100 acres planted with Bt transgenic cotton with the Cr1Ac gene planted, producers must plant 4 acres of conventional cotton (i.e. without the Cry1Ac gene), which CANNOT be treated with acephate, amitraz, endosulfan, methomyl, profenofos, sulprofos, synthetic pyrethroids, and/or Bt kurstaki insecticides labeled for control of tobacco budworm, cotton bollworm, and pink bollworm. This cotton must receive

38 the same or substantially similar management (fertility, weed control, pest control, etc.) as transgenic Bt cotton.

3) The eradication option. In areas involved in the pink bollworm eradication program, a modified resistance management plan was necessary for Bt cotton to fit the needs of the pink bollworm eradication program. Resistance management for Bt transgenic cotton fields in the eradication program requires that Bt cotton be planted with an embedded refuge of conventional cotton in a ratio of 95:5. Unlike the 4% refuge that will not be treated with insecticides, Bt fields in the eradication program will be treated with insecticides when scouting reveals that the refuge has a 5% level of infestation (El-Lissy and Staten 2005).

Research shows that combining Cry2Ab gene with the Cry1Ac gene (Bollgard® II) provides equal or better control of pink bollworm than single gene (Cry1Ac) varieties or other varieties, such as WideStrike®, which combines the Cry1Ac with Cry1F (inactive against pink bollworm). Resistance studies of varieties employing the Cry1Ac and Cry2Ab genes show that except for one field strain collected from Tornillo, El Paso County, Texas, all strains of pink bollworm collected from various field populations have retained significant susceptibility to both endotoxins (Marchosky et al. 2001, Dennehy et al. 2004). The belief is that stacking genes from the two unrelated toxins will reduce the likelihood of selecting resistance in pink bollworm during the comparatively short duration of the eradication program. Nevertheless, the presence of a significantly less susceptible strain in the El Paso area reinforces requirement for the 95:5 imbedded refuge, which will be retained and treated when necessary with insecticides registered for pink bollworm control (El-Lissy and Staten 2005).

Research also has shown that the extremely high levels of PBW control provided by all Bt lines give higher second picked yields in full-season cotton relative to non-Bt lines of the same variety. This is suggests excellent late-season control of pink bollworm by available and future Bt varieties.

Pink bollworm eradication

The pink bollworm continues to seriously affect western cotton-growing regions that are critical for the export of fiber, and production of seed for the entire U.S. Cotton Belt. The eradication of the pink bollworm will provide significant economic gains for cotton producers through lower production costs, higher yields, and better quality of fiber. An additional benefit of eradication will be its positive effect on the environment through significant reductions in pesticide usage.

Previous attempts to eradicate pink bollworm from the United States have failed. The latest attempt during the late 1980s and early 1990s in Arizona and southern California used several innovative practices in the Parker Valley of Arizona and the Mexicali Valley of California, employing sterile insect releases, pheromone mating disruption, application of insecticides and several cultural practices to shorten the growing season. In spite of significantly reducing pink bollworm populations, the program ultimately failed to achieve its objective. Pink bollworm continues to be the principal pest of cotton in Arizona and California, and is a key pest of cotton in west Texas (El-Lissy and Staten 2005).

The present pink bollworm eradication program begun in 1999 utilizes a more diverse blend of control methodologies than has been used in other successful area-wide eradication programs. It simultaneously incorporates an unprecedented number of highly effective control methods implemented within a harmonized system designed to maximize the opportunity of achieve the goal of eradicating one of the oldest and most destructive cotton pests in the world.

In its annual meeting on October 9-10, 2000, in El Paso, Texas, the National Cotton Council's Pink Bollworm Action Committee recommended launching a "bilateral" PBW

39 eradication program in the United States and northern Mexico. Through the coordinated efforts of cotton producer communities, and federal, state, and local entities in the U.S. and Mexico, the plan is to implement the eradication program in three phases. Phase I began in 2001/2002, and consists of the El Paso/Trans Pecos region of west Texas, south-central New Mexico, and northern Chihuahua, Mexico. Phase II, to begin in 2006, consists of cotton-growing areas in southeastern and central Arizona. Phase III, proposed to start in 2008, consists of western Arizona, southern California, and the Mexicali Valley of northwest Mexico (Fig. 4).

Fig. 4. Pink bollworm eradication plan.

The new approach to eradication employs six mutually supporting elements.

1) The first element is to shorten the growing season, creating a host-free period. This makes season-to-season survival difficult.

2) The second element consists of extensive planting of transgenic Bt cotton varieties. Several Bt cotton varieties of upland cotton containing the Cry1Ac gene were available from industry at the outset of the eradication program. Efforts continue by industry to stack other Bt genes in upland cotton and to develop Bt varieties of Pima cotton that make them less vulnerable to pink bollworms and other Lepidopteran pests.

3) The third element is to disrupt pink bollworm mating with application of controlled-release formulations of gossyplure. This scent confuses male moths and not only makes finding females nearly impossible but also shuts down mate finding flight activity by male moths.

4) The fourth element is the release sterile pink bollworm moths into cotton fields.

5) The fifth element is the application of insecticides for pink bollworm control when field monitoring shows infestation levels of 5 percent.

40 6) The sixth element is mandatory crop residue destruction to destroy as many overwintering pink bollworms as possible, while making their overwintering habitat much less survivable.

The eradication program began in 1999 in El Paso County and is presently under way in different locations throughout the Trans Pecos of Texas, New Mexico eastern Arizona, and Mexico's northern state of Chihuahua. The operational components include:

1) mapping to identify cotton field locations, acreage, and genotypes in an eradication area; 2) detection of pink bollworm adults and larvae by trapping and field monitoring, in which field scouts visually inspect squares, blooms and bolls for infestations; and

3) control using cultural practices (shortened season, regulations on crop residue destruction, etc.), widespread planting of Bt transgenic cotton varieties, mating disruption with pheromone, sterile moth releases, and minimal insecticide applications.

Eradication in the Trans-Pecos and Phase I area. The program began in 1999 as a combined boll weevil and pink bollworm eradication program. A farmer referendum approved an assessment of $20 per bale which would pay out the cost of eradication of both species by 2008. Boll weevil had been eradicated in the El Paso Valley eight years earlier, and boll weevil eradication had entered a maintenance phase in the Pecos Valley only a few years earlier. The primary effort in the Trans Pecos would be the eradication of pink bollworm.

In 1999, the program began in the El Paso Valley with trapping and mapping of fields. In 2000, eradication efforts began in the Trans Pecos area, with trapping, Bt cotton, mating disruption and minimal pesticide applications. In 2002, eradication efforts extended to adjacent areas of New Mexico and the state of Chihuahua, Mexico. Mating disruption in 2000 began with aerial application of No Mate® fibers. However, fibers had to be applied several times during the season, and not all fields could be treated by air. In spite of the labor cost of hand application, season-long control by the long-lasting PB Rope L® formulation proved much less costly and more effective than multiple applications of fiber formulations.

The program was modified in 2002 because federal budget constraints prevented mass rearing and release of sterile insects. The program continued without sterile insect release through 2003. In the Pecos Valley, extensive planting of Bt cotton varieties since the late 1990s had effectively maintained pink bollworm populations at very low levels.

Federal funds for sterile insect release did not become available until 2004. In 2004, sterile insect releases began throughout the Trans Pecos region. In 2005, sterile insect release began in May throughout the Phase I area, including west Texas, central New Mexico, eastern Arizona and Chihuahua, Mexico. The result of the addition of the sterile insect component took pink bollworm eradication from a field by field program to an areawide eradication program.

The delay in bringing sterile insect release on line in the eradication program produced a budget problem in the program. Successful eradication of the boll weevil saw that component of the program paid off on time. However, it also saw a longer period of pink bollworm eradication, which caused the pink bollworm component go over budget. In May, 2005, a new referendum was sent to farmers in the Phase I area to extend pink bollworm eradication and its associated budget pay out period.

Participating non-Bt cotton and Pima cotton were assessed at $20 per acre. Bt fields were assessed at $10 per acre because Bt cotton producers were bearing a significantly greater share of the cost of one of the components of the program.

41 Extending the payout period for several additional years will provide the time for the full eradication program to effectively take pink bollworm out of the Trans Pecos cotton agroecosystem.

Where cultural practices, mating disruption and applications of pesticides extend only to the edge of cotton fields, sterile male release goes area wide. Sterile insects move inside and outside cotton fields. They can move to areas where moths are emerging from fields not planted to cotton, such as those rotated from cotton planted the previous year. They also can mix with moths migrating from one field to another. The sterile insect technique is the only component of the system than can do this.

Eradication in the High Plains and Phase II area. There is no anticipated plan to extend eradication to the recent infestation of the High Plains by pink bollworm. The High Plains production area is regarded as a marginal habitat for pink bollworm, much as the San Joaquin Valley of California, which is infested by pink bollworms from production zones more favorable to its overwintering. Because of the obligatory short season and severe winters of the Texas High Plains, the present view is to eradicate pink bollworm from the adjacent Phase I and Phase II areas in New Mexico. This will allow its elimination by the environment, the planting of Bt cotton varieties and ordinary control practices. The main emphasis will be to deal with reinfestation of the Phase I area from the High Plains as part of a post- eradication monitoring and maintenance program. This will include cultural practices, mating disruption, sterile insect release and applications of pesticides when necessary. It is expected that once the primary source of infestation of the High Plains from adjacent areas of New Mexico has eradicated pink bollworm, it will quickly fade from the High Plains.

Mid- and late-season plant bugs and stink bugs

Changes in cotton varieties, production practices and boll weevil eradication have produced an environment favorable to damage by plant bugs and stink bugs. Plant bugs, a general term for insects in the family Miridae, feed on cotton terminals, squares and small bolls. Plant bugs affecting Texas cotton during mid- to late-season include species of Lygus and Creontiades species. Stink bugs, a general term for insects in the family Pentatomidae, feed on cotton terminals, squares and bolls through the boll maturation stage. There are several things producers can do to reduce the impact of plant bugs and stink bugs as a yield limiting factors in mid- to late-season cotton.

1) Control broadleaf weeds in and around fields early, before they can become a host for bugs. At the least, do not kill or mow blooming weeds and cause plant bugs to move into cotton fields during fruiting.

2) Decision-makers such as Extension Entomologists and Extension Agents-IPM, scouts, scouts, County Extension Agents, and others providing advice to cotton producers must be more cognizant of bug populations. For years we have concentrated our scouting for worms and weevils. However, with the changes brought on by boll weevil eradication and widespread planting of Bt cotton varieties, a concomitant shift must occur in the emphasis on sampling for bugs. Plant bug nymphs are extremely small and hard to find, particularly if scouts are not sampling for them. Sampling methods and economic thresholds exist in the different production regions for both Lygus and stink bugs. Scouting must employ these methods and control decisions should be geared to economic thresholds for these pests in mid- to late season.

3) Stink bug sampling in late-season cotton must include the examination of the inside carpel wall of cotton bolls for the "feeding warts" or stained lint, which are characteristic of stink bug damage. At this point, this is the best way to assess damage. In problem areas, plant bugs can significantly contribute to these injury symptoms on retained bolls and must be managed properly early. Use of Lygus bug thresholds will protect potential yield. Monitoring square

42 retention through mid-season and boll damage in mid- to late season is essential for tracking bug problems.

4) Plant bugs are easy to control early in the season and all recommended products do an excellent job of control (see efficacy tables). Problems arise in mid- to late-season when the plants are larger and have lapped the middles. Then it is important to consider increasing spray volume and concentrating on doing a good job with applications. Mid- to late-season control of plant bugs and stink bugs is not the time to use reduced rates of insecticides or lower spray volumes. Consider a minimum of 5 GPA by air and 10 GPA by ground for applications. Producers must not reduce rates below recommended levels. Recent studies show that all of the products will provide adequate control with proper application. Because of canopy closure and pest biology, multiple applications may be required to achieve adequate control.

5) Be aware of surrounding crops and the impact they can make on plant bugs and stink bugs in cotton. Crops such as corn, grain sorghum, soybeans and legume forages all are attractive to lygus bugs and stink bugs. Harvesting of these crops can contribute significantly to bug migrations into mid- to late season cotton. Cotton next to these crops should be monitored closely for developing problems.

6) Producers must not get behind in management of bug populations. Once populations get extremely high in mid- to late-season it can be difficult to get them under control. The key to prevent this from happening is to monitor closely and apply pesticides when bugs exceed economic thresholds. Plant bugs and stink bugs are not randomly distributed in the field. They are often clumped in spots throughout the field, making them easy to miss until they develop into general outbreak levels across a field. It is imperative to spot check in several locations in a field to find "hot spots" and deal with bug problems early.

As plant bugs and stink bugs emerge as key pests in cotton, there is a need to concentrate pest management efforts on the bug complex. However, it is easier to manage Lygus bugs and stink bugs than boll weevils, bollworms, tobacco budworms or pink bollworms. Most products registered on cotton for plant bug and stink bug control are highly effective when applied in accordance with label directions (see efficacy tables).

Mid-season Lygus bugs

Eastern, Southern and Blacklands. In the Eastern, Southern and Blacklands areas, Lygus bugs can continue to damage the mid-season and late-season crop. Use the same sampling techniques and chemical control suggestions given previously.

Lygus bug control treatments begin when lygus bug counts exceed 20 to 30 per 50 sweeps (count nymphs as two) in fields where plants failed to retain squares and set bolls normally during the first 4 to 5 weeks of fruiting.

High Plains, Rolling Plains and Trans Pecos. In the High Plains, Rolling Plains and Trans Pecos regions of Texas, the western tarnished plant bug (Lygus hesperus) is one of several Lygus species that feeds on cotton terminals, squares and small bolls. Adults are 1/4 inch long, have a conspicuous triangle in the center of the back, are winged, and vary in color from pale green to yellowish brown with reddish brown to black markings.

Immature lygus bugs are called nymphs. They are uniformly pale green with red-tipped antennae; late instars have four conspicuous black spots on the thorax and one large black spot near the base of the abdomen. The nymph's wings are not developed, but nymphs can move rapidly and are difficult to detect in cotton foliage. Small nymphs may be confused with aphids, cotton fleahoppers and leaf hopper nymphs. Plant bugs prefer legumes to cotton and usually are found in large numbers in areas of alfalfa or potato production or areas

43 providing wild hosts such as clovers, vetches, mustard and dock. Lygus bugs are attracted to succulent growth; their feeding results in shedding of squares and small bolls, stunted growth and boll deformation.

Feeding damage to small bolls is often characterized as small black spots or small, sunken lesions. The feeding that causes these spots or lesions may or may not penetrate the boll wall and damage developing seeds or lint. Damage to blooms appears as black anthers and puckered areas in petals.

Management and decision making for lygus bug control is determined by their abundance in relation to the fruiting condition of the cotton plants. Fields should be inspected for lygus bugs at 4- to 5-day intervals using a drop cloth (see discussion on page 7). During the first week of squaring, the economic threshold is one lygus bug adult or nymph per 3 feet of row combined with less than 90 percent square set. In the second week of squaring, the economic threshold is one lygus bug adult or nymph per 3 feet of row combined with less than 85 percent square set. In the third week of squaring, the economic threshold is one lygus bug adult or nymph per 3 feet of row combined with less than 75 percent square set. After the third week of squaring, the economic threshold is two lygus bug adults or nymphs per 3 feet of row with less than acceptable fruit retention.

After peak bloom, begin treatment when drop cloth counts exceed two lygus bug adults or nymphs per 3 feet of row and plants have failed to retain squares and set bolls normally during the first 4 to 5 weeks of fruiting.

Research indicates that the western tarnished plant bug (Lygus hesperus) may be more difficult to control with insecticides than other plant bugs and may require the use of higher labeled rates of suggested insecticides.

Creontiades spp. Lower Rio Grande Valley

In the Lower Rio Grande Valley, species of Creontiades plant bugs can produce injury similar to that produced by Lygus bugs in other production areas of Texas. Creontiades spp. is a plant bug that has become more common in the Lower Rio Grande Valley. Creontiades species found in the Lower Rio Grande Valley are small (1/4 inch in length), narrow bodied, yellow-green plant bugs. The insect goes through several molts or instars (nymphs).

The smallest nymphs are about the size of a large cotton fleahopper nymph, with similar rapid movement around the plant structures. Differences between Creontiades species and cotton fleahoppers exist that make identification easier. Cotton fleahopper nymphs have red eyes and both adult and nymphal stages of cotton fleahoppers have bar marks on the antennae. Creontiades nymphs do not have red eyes, have a reddish band on the rear of the pronotum and no bars or similar markings on their antennae. As a general rule, the adult male Creontiades is slightly darker green in color than the female.

Damage from Creontiades species in cotton can be square and small boll loss. A characteristic clear yellow liquid (Creontiades spp. frass) is often left on the fruiting structure where Creontiades have fed. Squares and small bolls may suffer damage ranging from just surface feeding and boll malformation to complete fruit loss.

Creontiades plant bug management and decision making. The need for plant bug control is determined by the insect abundance in relation to the fruiting condition of the cotton plants. Inspect fields at 4- to 5-day intervals during the fruiting period. Take 50 sweeps at each of the four locations in the field by sweeping a 15- to 16-inch net across the top of one row in such a way that the top 10 inches of the plants are struck. Begin treatment when plant bug counts exceed 20 to 30 per 50 sweeps in fields where plants failed to retain squares and set bolls normally during the first 4 to 5 weeks of fruiting.

44 Mid- and late-season stink bugs

Eastern, Southern and Blacklands

Species of stink bugs that feed on cotton in the Eastern, Southern and Blacklands region include the southern green stink bug (Nezara viridula), brown stink bug (Euschistus servus), harlequin bug (Murgantia histrionica), rice stink bug (Oebalus pugnax), the spined shouldered stink bug (Podisus maculiventris) and several others. In mid- to late-season stink bugs feed on squares and bolls. Feeding on bolls may cause bolls to shed and also produces seed damage, lint staining and reduction of yield.

Management and decision making is based upon scouting and established economic thresholds. Cotton plants are examined in about six feet of row in several locations in the field. When there is an average of one or more stink bugs per 6 feet of row, feeding can cause excessive loss of squares and small bolls and may stain lint. Additionally, at least 50 small bolls (the diameter of a quarter) should be examined. If 20 percent of the small bolls have evidence of internal feeding (callous growth on internal boll wall and/or stained lint) and stink bugs are present then treatment should be considered. Stink bugs often are clumped near field margins. Spot treatment provides effective control when this situation exists. Second through fifth instar stink bug nymphs and adults can damage bolls. Fourth and fifth instars can cause the same level of damage as adults.

High Plains, Rolling Plains and Trans Pecos

Species of stink bugs that feed on mid- to late-season squares and bolls in the High Plains, Rolling Plains and Trans Pecos regions include the conchuela stink bug (Chlorochroa ligata). Feeding on bolls may cause boll shed and/or seed damage and lint staining. Stink bugs may move into cotton when grain sorghum in the area starts to mature.

Management and decision making. Examine 6 row feet of cotton in several locations in the field. When there is an average of one or more stink bugs per 6 feet of row, feeding can cause excessive loss of squares and small bolls and may stain lint. Additionally, at least 50 small bolls (the diameter of a quarter) should be examined. If 20 percent of the small bolls have internal injury from stink bugs and stink bugs are present then treatment should be considered. Stink bugs often are clumped near field margins.

Lower Rio Grande Valley

Evidence from the Lower Rio Grande Valley suggests that stink bugs are occasional late-season pests and that fields accumulating 475 DD60s are safe from stink bugs.

Beet Armyworm

Lower Rio Grande Valley

Beet armyworm eggs are laid on both leaf surfaces in masses covered by a whitish, velvety material. Young beet armyworms "web up" and feed together on leaves, but eventually disperse and become more solitary in their feeding habits. Early season infestations feed on leaves and terminal areas. Occasionally they destroy the plant terminal, causing extensive lateral branch development and delayed maturity. Larvae skeletonize leaves rather than chewing large holes in them. Sometimes damaging infestations will develop late in the season when they also feed on terminals, squares, blooms and bolls. Several factors can contribute to these late-season beet armyworm outbreaks including: mild winters (no prolonged freezing temperatures); late planting; delayed crop maturity; heavy early-season organophosphate or pyrethroid insecticide use; prolonged hot, dry weather; presence of beet armyworms prior to bloom; and weather conditions that support long-distance migration.

45 Additional characteristics of high risk fields are: sandy and droughty soils; skip-row planting; fields with skippy, open canopies; drought-stressed plants; and fields infested with pigweed. The likelihood of a heavy outbreak increases as more of these factors occur in a given location. However, when beet armyworm populations are high, all fields are susceptible. When beet armyworms begin to damage fruit, control may be justified. Infestations may be spotty within a field and careful scouting is necessary to determine the need for, and field area requiring, control. Beet armyworms larger than ½ inch in length may be difficult to control.

Management and decision making in the Lower Rio Grande Valley must include scouting fields by using the methods described for bollworm and tobacco budworm. When beet armyworms are feeding on fruit forms, then the thresholds are the same as with bollworm and tobacco budworm.

Eastern, Southern and Blacklands

Beet armyworm eggs are laid on both leaf surfaces in masses covered by a whitish, velvety material. Young beet armyworms "web up" and feed together on leaves, but eventually disperse and become more solitary in their feeding habits.

Early-season infestations feed on leaves and terminal areas. Occasionally they destroy the plant terminal, causing extensive lateral branch development and delayed maturity. Larvae skeletonize leaves rather than chewing large holes in them. Damaging infestations sometimes develop late in the season when beet armyworms also feed on terminals, squares, blooms and bolls. Several factors can contribute to these late season beet armyworm outbreaks. These factors are: mild winters (e.g., absence of prolonged freezing temperatures); late planting; delayed crop maturity; heavy early season organophosphate or pyrethroid insecticide use; prolonged hot, dry weather conditions; presence of beet armyworms prior to bloom; and weather conditions that support long-distance migration.

Additional characteristics of high risk fields that consistently appear to fit a pattern for developing beet armyworm problems are: sandy and droughty soils; skip-row planting; fields with skippy, open canopies; drought stressed plants; and fields infested with pigweed. The likelihood of a heavy outbreak increases as more of these factors occur in a given location. However, when beet armyworm populations are high all fields are susceptible. When beet armyworms begin to damage fruit, control may be justified. Infestations usually are spotty within a field, and careful scouting is necessary to determine the need for and field area requiring control. Beet armyworms longer than ½ inch may be difficult to control.

Management and decision making include scouting fields with the "Whole Plant Inspection Method " described in the bollworm and tobacco budworm section. The early detection threshold, hatching egg masses, (from initiation of squaring to cutout) is two "active hits" (i.e., recently hatched egg masses with actively feeding larvae) detected per 100 row feet . If conditions optimal for a beet armyworm outbreak exist, treatment should be considered. Hits can be detected by observing plant leaves by walking along a row for a measured distance. Remedial Threshold (advanced infestation during mid-season): When small worm counts exceed 20,000 per acre and at least 10 percent of the plants examined are infested, control may be warranted.

High Plains, Rolling Plains and Trans Pecos

Beet armyworm eggs are laid on both leaf surfaces in masses covered by a whitish, velvety material. Young beet armyworms "web up" and feed together on leaves, but eventually disperse and become more solitary in their feeding habits.

46 Damaging infestations sometimes develop late in the season when beet armyworms also feed on terminals, squares, blooms and bolls. During early stages of infestations, which occur immediately after egg masses have hatches, larvae feed on leaves and terminals. Occasionally they destroy the terminal. Larvae skeletonize leaves rather than chewing large holes in them. Later instars spread to fruiting forms and attack squares and bolls. Insecticide applications may be warranted when plants with undamaged terminals approach the lower optimal plant stand limits of two plants per row foot for dryland production and four plants per foot of row in irrigated production.

Several factors can contribute to these late-season beet armyworm outbreaks. These factors are: mild winters (e.g., absence of prolonged freezing temperatures), late planting, delayed crop maturity, heavy early-season organophosphate or pyrethroid insecticide use, prolonged hot and dry weather conditions, presence of beet armyworms prior to bloom, and weather conditions that support long-distance migration. Additional characteristics of high risk fields that consistently appear to fit a pattern for developing beet armyworm problems are: sandy and droughty soils; skip-row planting; fields with skippy, open canopies; drought stressed plants; and fields infested with pigweed. The likelihood of a heavy out-break increases as more of these factors occur in a given location. However, when beet armyworm populations are high all fields are susceptible. When beet armyworms begin to damage the fruit, control may be justified. Infestations usually are spotty within a field, and careful scouting is necessary to determine the need for, and field area requiring, control. Beet armyworms longer than ½ inch may be difficult to control.

Beet armyworm management and decision making in the High Plains, Rolling Plains and Trans Pecos regions include scouting the field by using the "Whole Plant Inspection Method " described in the bollworm and tobacco budworm section.

The early detection threshold (hatching egg masses) is valid from initiation of squaring to cutout. It is two "active hits" (i.e., recently hatched egg masses with actively feeding larvae) detected per 100 row feet with conditions optimal for a beet armyworm outbreak. At the early detection threshold, treatment should be considered.

In mid- to late season, control is warranted when beet armyworms reach the "remedial threshold " for advanced infestations during mid-season to late-season. The remedial threshold has been reached when infestations are feeding predominantly on leaves; small worm counts exceed 20,000 per acre, and at least 10 percent of the plants examined are infested. If beet armyworm larvae have shifted from feeding on foliage to feeding on squares, blooms and bolls, thresholds should be lowered toward the bollworm threshold of 5,000 small larvae per acre. When cotton matures and square feeding is of no consequence, thresholds should be raised to 20,000 small larvae per acre.

Cabbage looper and other loopers (Lepidoptera: Geometridae)

The caterpillar (larva) grows to be about 2 inches long, is light green and has three pairs of "true" legs behind the head plus pairs of fleshy "false legs" (prolegs) on the 3rd, 4th and last or 6th segments behind the segment with the last pair of true legs (the abdominal segments). This arrangement of legs causes the caterpillar to crawl with a "looping" motion, similar to that of inchworms. Some specimens are marked with light stripes along the body. Adult moths are mottled grayish-brown with a 1 + inch wingspan. Each forewing is marked near its center with a pair of characteristic silver markings: a spot and a mark resembling a "V" or and "8" with an open end.

Other looper species include the celery looper (Syngrapha falcifera) and the soybean looper (Pseudoplusia includens). Cotton leafworms in the family Noctuidae can be separated from loopers, sometimes called "inchworms," in the family Geometridae, by the configuration of the "false legs" or prolegs. Inchworms (Lepidoptera: Geometridae) are missing the pair on

47 the 3rd (abdominal) segment behind the segment containing the third pair of "true" legs, and have only two pairs of prolegs (on segments 4 and 6).

Larvae grow up to 2 inches long, have five pairs of abdominal prolegs, and their coloration varies from all light green to dark brown with dark and light-colored stripes down the body. They develop through six stages (instars) before pupating. Development from egg to adult occurs in 31 to 46 days. Caterpillars feed on tender leaves, causing skeletonization and defoliation, with injury on soybean plants being most severe on the upper part of the plant. Host plants include primarily legumes such as alfalfa, cowpea, peanuts and soybeans. In the south, several generations can occur annually.

Winter is spent in the pupal stage inside of a cocoon attached by one side to the host plant material. Adults emerge in the spring, mate and fly to a suitable host plant. Eggs are smooth, light green and slightly flat. Within about 3 days, small caterpillars hatch from the eggs. During a period of about 4 weeks caterpillars feed and develop through several stages (instars) before spinning a silk cocoon in which they form a greenish to brownish 3/4 inch long pupa. Adults emerge in about 13 days unless they overwinter. Development from egg to adult can be completed in about 35 days. Four generations or more can be produced each year.

Lower Rio Grande Valley

Cabbage looper eggs are laid singly, mainly on the lower surfaces of the leaves. Their feeding damage is characterized by leaf ragging or large holes in the leaves. Looper larvae often are killed by disease before economic foliage loss occurs.

No economic threshold has been established for cabbage looper the Lower Rio Grande Valley because outbreaks of this pest rarely occur. Insecticide treatments generally are not recommended.

Eastern, Southern and Blacklands

Moths of cabbage looper (Trichoplusia ni), soybean looper (Pseudoplusia includens) and cotton leafworm (Alabama argillacea) lay eggs singly, mainly on the lower surfaces of leaves. Larval feeding damage is characterized by leaf ragging or large holes in the leaves. Larvae often are killed by a disease before economic foliage loss occurs. An economic threshold for these foliage feeding caterpillars have not been established in the Eastern, Southern and Blacklands production areas. As a general guideline, treatments are applied when 10 percent of the "key leaves" are infested with worms. The key leaf is the third one down the main stem from the tip (usually the highest leaf on the plant).

High Plains, Rolling Plains and Trans Pecos

Cabbage looper eggs are laid singly, mainly on the lower surfaces of leaves. Larval feeding damage is characterized by leaf ragging or large holes in the leaves. Looper larvae often are killed by a disease before economic foliage loss occurs. No economic threshold has been established cabbage loopers in High Plains, Rolling Plains or Trans Pecos regions, and looper outbreaks rarely occur in these production areas. Insecticide treatments generally are not recommended.

Spider mites (Acari: Tetranychidae)

Spider mites are usually secondary pests that appear in mid- to late-season cotton after applications of pesticides for other pests. Mites also may be moved by high winds or equipment from nearby crops which already have heavy infestations. They become most prevalent during periods of hot, dry weather. Infestations usually begin at the margins of

48 fields where dust from roads inhibits activity of mite predators. Spider mites infest the undersides of leaves, where they remove the sap from the plant and cause the leaves to discolor. They may also infest bracts of squares and bolls, causing the bracts to desiccate and squares or small bolls to shed. Severe infestations can defoliate the cotton plant. Mite infestations most often occur in spots and in field margins. Spider mite outbreaks usually follow multiple applications of insecticides, since insecticides destroy natural spider mite predators.

Decisions to apply acaricides are made when mites begin to cause noticeable leaf damage. Spot treatment of fields is encouraged when infestations are restricted to small areas. Two applications at 5-day intervals may be required for acceptable control. In certain locations, some mite species are highly resistant to miticides and are difficult to control with available materials. Thorough coverage of the plant canopy with the miticide is essential to achieve good mite control. This may require high gallonage sprays delivered by ground application equipment. Hollow cone nozzles should be used to apply acaricides for the control of spider mite outbreaks because they give more thorough leaf coverage than other types of nozzles. The spray should be directed into the canopy with drop nozzles. Drops with at least one set of nozzles oriented upward to give full coverage to the undersides of leaves usually provide better control than nozzles oriented to treat only the tops of leaves.

Other mid- and late-season pests

Armyworms, including beet armyworm, fall armyworm (Spodoptera frugiperda) and yellowstriped armyworm (Spodoptera ornithogalli) occasionally cause damage to mid- and late-season cotton. Damage from armyworms results from both defoliation and feeding in bolls. Saltmarsh caterpillar (Estigmene acrea) outbreaks occasionally occur later in the season but rarely cause economic damage. Southern armyworm (Spodoptera eridania), cotton leafworm (Alabama argillacea), minor cotton leafworm ( texana), brown cotton leafworm (Acontia dacia), cotton square borer (Strymon melinus), cotton leaf perforator (Bucculatrix thuriberiella), and omnivorous leafroller (Platynota stultana) may occur later in the season but rarely occur in numbers sufficient to cause economic damage. Economic thresholds do not exist for square borers and foliage feeding caterpillars. Control is a matter of judgment. Insecticides are most effective when applied when worms are small.

The cotton stainer (Dysdercus suterellus) and several leaf-footed bugs (Coreidae), including Leptoglossus phyllopus and L. phyllopus, may also cause damage similar to that of stink bugs in late-season cotton. The cotton stainer is mainly a pest of Pima cotton (Gossypium barbadense). It damages developing bolls by puncturing seeds and causing plant sap to exude from the feeding site. The plant sap stains the lint an indelible yellow color. Feeding by the cotton stainer also interferes with the bolls' natural development. No economic thresholds exist for these bugs and treatment is a matter of judgement. Efficacy of insecticides labeled for these pests is similar to that obtained for stink bugs (see efficacy tables).

49 Insecticides

Avermectin (Abamectin®®, Zephyr ) Avermectin is a macrocyclic lactone insecticide/acaricide registered on cotton for the control of spider mites (Tetranychidae). The use rate is 0.01 to 0.02 lb ai per acre, with a limit of 3 applications per season. Applications for mites may occur by ground or air, but most applications are made by ground (60 - 70%). It exhibits excellent translaminar movement into plant tissue and forms a reservoir within treated leaves. Because avermectin is not systemic, good coverage is essential. Best results are obtained from ground spraying equipment or aircraft in a minimum spray volume of 5 gal/A. Death occurs within about four days. Avermectin is not ovicidal, and larval mites die only after consuming a lethal dose. This may occur from chewing their way out of treated eggs or from consumption of treated leaf tissue. Larvae that make it to the leaves die as they begin to feed on leaf tissue. It is advisable to avoid the use of reduced rates and to use avermectin only once or twice in a given season because individual spider mites differ in their tolerance to this acaricide and populations rapidly develop resistance. Repeated use of any a single miticide removes the susceptible individuals from the population, leaving only the most resistant mites to reproduce. Resistance management practices should include rotation of chemical classes when making treatments for spider mites in cotton. Avermectin also kills predatory mites but is comparatively inactive against insects that prey on mites. Resurgence of mite populations after treatment with avermectin not likely in cotton when insect mite predators are present. Avermectin is very effective acaricide but very rarely used (if ever) because of expense.

Acephate (Orthene®®, Address ) Commercial formulations include Orthene®® 90S, Orthene 75S, and Orthene® 97PE. For bollworm/budworm eggs, ovicidal applications for are made primarily by air. The application rate averages 0.45 pounds ai per acre. The preharvest interval is 21 days. The restricted-entry interval is 24 hours. Most growers do not use acephate as an ovicide because of widespread planting of Bt cotton and the availability of more effective caterpillar treatments. Similarly, to control the bollworm/budworm complex, larvicidal applications occur on a small percentage of the cotton acres in Texas. It is not listed as an ovicide in any of the 2005 pesticide supplements to cotton insect control guides for Texas, and is not listed for larval bollworm/budworm control in the guide for the High Plains, Rolling Plains and Trans Pecos regions of Texas because efficacy is poor, Texas does not recommend ovicides used alone.

Acephate is effective against cotton fleahoppers, Lygus and other plant bugs (Miridae). The type of application is evenly divided between ground and air equipment. Rates range from 0.25 lbs a.i. per acres during early season to 0.9 lbs a.i. per acre. However, multiple applications applied at 2 to 3 day intervals are often required to obtain control of heavy infestations. The preharvest interval is 21 days. The restricted-entry interval is 24 hours. Acephate is categorized in a different chemical sub-class compared to most other organophosphates used on cotton and one of the few 'older' insecticides to which plant bugs have not developed high levels of resistance. Acephate is used to control plant bugs, thrips, and stink bugs throughout the growing season.

Acephate is registered for thrips control in cotton. Application methods include seed treatments and in-furrow sprays with ground equipment. In-furrow application rates range from 0.75 to 1.0 pounds a.i. per acre. The preharvest interval is not specified on the label. The restricted-entry interval is 24 hours. In addition to being used as an at-planting seed treatment and as an in-furrow treatment for thrips control, acephate is also commonly used as a foliar treatment to control thrips on seedling cotton. Rates of 0.2 to 0.25 lbs ai/acre are effective against all species of thrips in Texas. Higher rates may be required for western flower thrips.

50 Acephate also is effective against whiteflies, particularly when mixed with fenpropathrin. Bandedwinged whitefly, silverleaf whitefly and sweetpotato whitefly require 0.5 to 1.00 lb ai per acre for effective control. It is listed for control of Bemisia (silverleaf/sweetpotato) whiteflies in the guide for the Lower Rio Grande Valley. Acephate controls cutworms and fall armyworms when applied at rates between 0.8 and 1.0 lb ai per acre. It controls stink bugs at application rates of 0.75 to 1.0 lb ai per acre.

Acetamprid (Intruder®) Acetamiprid (Intruder® 70 WP) is registered for the control of fleahoppers, aphids and whiteflies in cotton. In Texas it is recommended and applied both for cotton fleahopper and for aphids. It is the most widely used insecticide for aphids and effective control is achieved from applications of 0.4 to 0.6 ounces per acre. However, it is not listed in the Extension guide for the Lower Rio Grande Valley because since 1999 no whitefly outbreaks have occurred and very low whitefly populations have made efficacy data impossible to collect. Efficacy data from the Desert Southwest (Arizona and California) is not considered applicable to the Lower Rio Grande Valley of Texas. Applications of acetamprid are made with both ground and aerial equipment. Application rates for fleahoppers and aphids are 0.025 to 0.05 lb ai per acre. The preharvest interval is 28 days. The restricted-entry interval is 12 hours. Insecticide trials in Texas show that acetamiprid is the most efficacious of the neonicotinoids for controlling aphids. It may see increased use in the future. When applied for bandedwinged and Bemisia species of whitefly, acetamiprid rates of 0.025-0.05 lb ai per acre are effective. Whitefly retreatment may be necessary every 5 to 14 days under conditions of severe outbreak. Acetamprid is not among insecticides recommended for whitefly control in the Lower Rio Grande Valley and does not occur in any of the insecticide guides for cotton insect control.

Aldicarb (Temik®) Aldicarb (Temik® 15G) oxime carbamate insecticide is an effective treatment for thrips and has been used for many years to protect seedling cotton from thrips injury. All applications are in-furrow treatments applied with ground equipment. Application rates average 0.45 and 1.05 lb ai per acre. The preharvest interval is 90 days. The restricted-entry interval is 48 hours. Aldicarb is the most commonly used soil applied insecticide. This is because of its excellent, long-lasting activity against thrips and because, when used at adequate rates, it provides good suppression of nematodes. Aldicarb also provides early season suppression of plant bugs and cotton aphids but does not control cutworms. Hazards to both the environment and applicator have combined recently with the cost of control to reduce the total amount of alidcarb applied by Texas cotton producers, who are substituting formulations of imidacloprid.

Amitraz (Ovasyn®) Amitraz (Ovasyn®) formamidine acaricide/insecticide/ovicide is applied to cotton primarily to control eggs and early stage larvae of the bollworm/budworm complex. It also is an excellent miticide and is sometimes mixed with dicrotophos (Bidrin®) the control of aphids with amplified esterase resistance (overtranscription of nonspecific esterase genes). The restricted entry interval (REI) is 48 hours. The preharvest interval is 14 days.

Azinphos-methyl (Guthion®) Azinphos-methyl (Guthion®® 2E, and Sniper 2E) is applied primarily for boll weevil control. Boll weevil applications are made by ground and air with a slightly larger percentage being made by ground equipment. Application rates average 0.25 lb ai per acre. There is no preharvest interval for mechanically picked cotton. The restricted-entry interval is 48 hours. Now that all of Texas is now under Boll weevil eradication, applications of azinphos-methyl are expected to decline considerably. Presently, applications of azinphos-methyl have declined significantly because of active boll weevil eradication programs. Only a few areas in Texas still require producer-applied boll weevil insecticides.

51 Bifenthrin (Capture®) Bifenthrin (Capture® 2 EC) is used primarily for control of the bollworm/budworm complex in non-Bt cotton and is applied to less than 5 percent of cotton acres. It is also labeled for mites, and Extension guides suggest its use for mite suppression when it is applied for bollworm control. Both ground and aerial applications are used. The recommended rate is 0.04 to 0.1 lbs a.i. per acre. The restricted-entry interval is 24 hours and the preharvest interval is 14 days. Bifenthrin is registered for control of aphids in cotton. The application type is evenly divided between air and ground equipment. Application rates average 0.04 pounds a.i. per acre. The preharvest interval is 14 days. The restricted-entry interval is 12 hours. Presently, for various reasons, bifenthrin is not recommended for aphid control in Texas. Bifenthrin is also registered for control of cutworms at 0.04 v 0.1 lb ai per acre, for stink bug control at 0.06 lb ai per acre and for whitefly control at rates of 0.06 to 0.1 lb ai per acre.

Carbofuran (Furadan®) Carbofuran has been used effectively against aphids in Texas under emergency conditions. However, its use is rare because it is not labeled for that use. However, when OP and oxime carbamate resistant aphids have occurred in large outbreaks, it has been occasionally used under Section 18 exemptions, the last of which was approved by EPA on April 1, 2003. It is sometimes used under a Section 24c SLN for Texas as an in-furrow treatment at planting.

Chlorpyrifos (Lorsban®®, Lock-on ) Chlorpyrifos (Lorsban® 4 EC) is registered for control of pink bollworm, cutworms, cotton fleahopper, Lygus bugs and other plant bugs (Miridae), grasshoppers, beet armyworm, aphids and bollworm/budworm eggs and larvae. Applications are made by ground and air with the about the same proportion applied by air and by ground equipment. Application rates for fleahopper are 0.19 - 0.5 pounds a.i. per acre. The preharvest interval is 14 days. The restricted-entry interval is 24 hours. It is usually applied as an alternative to dicrotophos. Chlorpyrifos also is recommended for control of grasshoppers at 0.24 - 0.5 lb ai per acre, for aphids at 0.25 - 1.0 lb ai per acre, for cutworms at 0.75 to 1.0 lb ai per acre, and for beet armyworm at 1.0 lb ai per acre.

Chlorpyrifos (Lorsban®® 4E, Lock-on 2E) is applied for control of pink bollworm at application rates of 0.75 lb ai per acre. Applications occur in the Texas High Plains and Trans Pecos regions and are limited to fields where at least 5% of the cotton is infested with pink bollworm larvae or where other techniques (mating disruption and use of Bollgard® cotton) have failed to keep infestation levels below economic thresholds. This more limited use of chlorpyrifos serves to restrict the potential adverse impacts to the sites of application and precludes effects to many cotton fields where other techniques can effectively suppress pink bollworm populations. Site-specific decisions can be made to mitigate potential adverse effects from chlorpyrifos applications.

Applications for bollworm/budworm egg and larvae control seldom occur in Texas, and chlorpyrifos does not appear in the extension insecticide guides as an ovicide nor as a larvicide.

Cyfluthrin (Baythroid®) Cyfluthrin synthetic pyrethroid insecticide is applied to control bollworm but not tobacco budworm larvae. Bollworm applications are made by ground and air at application rates of 0.025 - 0.05 lb ai per acre. Approximately 1 or 2 applications are made each growing season on transgenic Bt cotton. Non-Bt cotton receives 2 to 5 applications per growing season. In the Gulf Coast growing areas, these applications are usually made as tank-mixes of several insecticides with cyfluthrin or as its formulation with imidacloprid (Leverage® 2.7 SE). However, very few applications are made with cyfluthrin alone. The pre-harvest interval is 0 days. The restricted-entry interval is 12 hours. Cyfluthrin will also effectively control boll weevil at 0.025 - 0.04 ai per acre. However, application intervals similar to those

52 recommended for the traditional phosphate insecticides (3 to 5 days under heavy pressure) are necessary to provide adequate control. When treatments are to be made for a bollworm-boll weevil complex a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate or carbamate boll weevil insecticide. Since pyrethroids are not more effective than phosphates or carbamates for boll weevil control, but are more effective for bollworm control, they should be reserved for bollworm management. Extension insecticide guides for cotton do not recommend using pyrethroids for boll weevil control alone or for early season pests because increased use may enhance the opportunity for insects to develop resistance to pyrethroids. Early use of pyrethroids also is not recommended because of their tendency to release or cause resurgence of secondary pests, such as aphids, spider mites and whiteflies. Boll weevil applications are made by ground and air with a larger percentage being applied by air. Application rates average 0.04 pounds a.i. per acre. There is no preharvest interval specified on the label. The restricted-entry interval is 12 hours. Cyfluthrin also is applied to control cutworms at 0.0125 - 0.025 lb ai per acre, Lygus bugs and other plant bugs at 0.025 to 0.04 lb ai per acre, stink bugs and grasshoppers at 0.025 to 0.05 lb ai per acre. In the Texas High Plains and Trans Pecos Regions of Texas, Cyfluthrin also is applied to control pink bollworms when infestation levels exceed 5% of susceptible bolls or where other techniques (mating disruption and use of Bt cotton) have failed to keep infestation levels below economic thresholds.

Cypermethrin (Ammo®) Cypermethrin (Ammo®® 2.5EC and Ammo WSB) synthetic pyrethroid insecticide is applied to control cotton bollworm, but Extension insecticide guides do not recommend it for control of tobacco budworm larvae. It is seldom used in Gulf Coast production areas. Bollworm applications of 0.04 to 0.1 lb ai per acre are made by ground and air with the majority applied by air. The preharvest interval is 14 days. The restricted-entry interval is 12 hours. Cypermethrin also effectively controls boll weevil at 0.04 - 0.1 ai per acre. However, application intervals similar to those recommended for the traditional phosphate insecticides (3 to 5 days under heavy pressure) are necessary to provide adequate control. When treatments are to be made for both bollworms and boll weevils, a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate or carbamate boll weevil insecticide. Since pyrethroids are not more effective than phosphates or carbamates for boll weevil control, but are more effective for bollworm control, they should be reserved for bollworm management.

Extension insecticide guides for cotton do not recommend using pyrethroids for boll weevil control alone or for early season pests because increased use may enhance the opportunity for insects to develop resistance to pyrethroids. Early use of pyrethroids also is not recommended because of their tendency to release or cause resurgence of secondary pests, such as aphids, spider mites and whiteflies. Boll weevil applications are made by ground and air with a larger percentage being applied by air. Cypermethrin also is applied for cutworms, saltmarsh caterpillars, Lygus and other plant bugs (Creontiades spp.: Miridae) at 0.04 - 0.1 lb ai per acre.

Deltamethrin (Decis®) Deltamethrin (Decis®) synthetic pyrethroid insecticide is applied for control of cotton bollworm but is not recommended for tobacco budworm. In the production areas along the Gulf Coast, there is fairly high use of deltamethrin for bollworm control. The recommended rate is 0.019 to 0.03 lb ai per acre. The restricted-entry interval is 12 hours and preharvest interval is 21 days. Deltamethrin also effectively controls boll weevil at 0.04 - 0.1 ai per acre. However, application intervals similar to those recommended for the traditional phosphate insecticides (3 to 5 days under heavy pressure) are necessary to provide adequate control. When treatments are to be made for both bollworms and boll weevils, a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate or carbamate boll weevil insecticide. Since pyrethroids are not more effective than phosphates or carbamates

53 for boll weevil control, but are more effective for bollworm control, they should be reserved for bollworm management.

Extension insecticide guides for cotton do not recommend using pyrethroids for boll weevil control alone or for early season pests because increased use may enhance the opportunity for insects to develop resistance to pyrethroids. Early use of pyrethroids also is not recommended because of their tendency to release or cause resurgence of secondary pests, such as aphids, spider mites and whiteflies. Boll weevil applications are made by ground and air with a larger percentage being applied by air. Deltamethrin also is applied for cutworms, saltmarsh caterpillars, Lygus and other plant bugs (Creontiades spp.: Miridae) and stink bugs at 0.019 to 0.03 lb ai per acre.

Dicofol (Kelthane®) Dicofol is applied for the control spider mites (Tetranychidae) at the rate of 0.75 to 2.0 lb ai per acre. Mite problems seldom occur in most production areas of Texas, but where they occasionally occur, there is some use of dicofol for their control. Dicofol has a 12-hour restricted entry interval and a 30-day preharvest interval. It is advisable to avoid the use of reduced rates and to use dicofol only once or twice in a given season because individual spider mites differ in their tolerance to this acaricide and populations rapidly develop resistance. Repeated use of any a single miticide removes the susceptible individuals from the population, leaving only the most resistant mites to reproduce. Resistance management practices should include rotation of chemical classes when making treatments for spider mites in cotton. Dicofol also kills predatory mites but is comparatively inactive against insects that prey on mites. Resurgence of mite populations after treatment with dicofol is less likely in cotton when insect predators are present.

Dicrotophos (Bidrin®) Dicrotophos (Bidrin® 8E) is a systemic organophosphate insecticide that is used extensively for thrips, cotton fleahoppers, Lygus and Creontiades plant bugs. Dicrotophos is the most widely used insecticide for fleahopper control and accounts for approximately 44% of all fleahopper treatments in Texas. Applications are made by ground and air. Aerial application is most common and is the only method used after irrigation begins or after significant rainfall. Application rates range from 0.25 to 0.5 lb ai per acre. The preharvest interval is 30 days. The restricted-entry interval is 48 hours. Lower rates usually provide effective control during early season, but the 0.5 lb ai per acre rate may be required during mid to late season. Multiple applications applied approximately 5 days apart are required to control heavy mid to late season plant bug infestations. Dicrotophos is also quite effective against plant bugs (Miridae) and is very effective against all species of stink bugs (Pentatomidae). It is a good choice for control of mixed populations of plant bugs and stink bugs during mid to late season. It is applied at 0.5 lb ai per acre to control Lygus and Creontiades plant bugs, and at 0.5 to 0.75 lb ai per acre for stink bugs.

Dicrotophos is somewhat effective against aphids. Applications are made by ground and air with most applications made by air. Application rates are from 0.25 to 0.5 lb ai per acre. Mid- and late-season outbreaks usually require higher rates to provide control. The preharvest interval is 30 days. The performance of dicrotophos for aphid control can be erratic because of resistance. A single, properly timed application of dicrotophos will usually provide adequate control of aphid infestations for short periods. However, resurgence of aphid populations after treatment often occurs. Efficacy is about the same as that of methomyl (Lannate®) and somewhat less than that of products like acetamiprid and thiamethoxam. Tank-mixes of dicrotophos with amitraz (Ovasyn®®) or profenofos (Curacron ) give better control of aphids than the use of dicrotophos alone.

Dicrotophos also controls boll weevils when applied at rates of 0.5 lb ai per acre. It is an acceptable organophosphate insecticide for boll weevil control, particularly when populations of stink bugs or plant bugs and boll weevils occur together. Dicrotophos also control thrips at

54 rates of 0.05 to 0.2 lb ai per acre, but more consistent and longer residual control by aldicarb, imidacloprid and thiamethoxam limit its use for thrips control.

Dimethoate (Cygon®®, De-Fend , Dimate®) Dimethoate, a systemic organophosphate insecticide with many trade names, is applied for cotton fleahopper, Lygus and other plant bugs (Creontiades spp., Hemiptera: Miridae), aphids, spider mites and thrips. The most common applications are for aphids, fleahoppers, Lygus and other plant bugs. Widespread resistance and more efficacious products reduce its use for spider mites and thrips. Applications are made by air and by ground with most being by ground equipment. Application rates for cotton fleahopper Lygus and other plant bug species are 0.125 to 0.25 lb ai per acre. However, application rates for Lygus species in the High Plains, Rolling Plains and Trans Pecos regions of Texas are made with the higher label rate. The restricted-entry interval is 48 hours. The preharvest interval is 14 days.

Disulfoton (Di-Syston®) Disulfoton (Di-Syston®® 15G and Di-Syston 8) is applied for control of thrips as an alternative to aldicarb (Temik®). All applications are in-furrow treatments applied with ground equipment at planing or shortly after. Application rates are 0.6 lb ai per acre. Disulfoton may be applied only once per season. Post planting applications are permitted only in irrigated cotton as a soil-incorporated side dress application if disulfoton was not applied at planting. The restricted-entry interval is 48 hours. The preharvest interval is 28 days in cotton. For various reasons, including lack of efficacy, disulfoton is not recommended for thrips control in the Lower Rio Grande Valley. Disulfoton also is labeled for control of aphids and spider mites in cotton, but for various reasons, including lack of efficacy, it does not occur in cotton insecticide guides and is not recommended for control of these pests in Texas.

Disulfoton may also be applied occasionally as a safener when used in conjunction with clomazone (Command®) herbicide applied PPI or PRE. Clomazone by itself can kill cotton. If it is to be used, either Di-Syston®® or Thimet insecticides must be used in-furrow at planting. Clomazone labels require the application of labeled rates of phorate or disulfoton at planting to provide safening from phytotoxicity. However, when used on cotton at the maximum recommended rates under adverse conditions such as extremely cool or wet or extremely dry weather, disulfoton may cause some delay in emergence, stunting of seedlings, or reduction of stand. Damage may be more pronounced in light, sandy soils. Plant injury may also occur when disulfoton is applied in conjunction with certain pre-emergent herbicides.

Emamectin benzoate (Denim®®, Proclaim ) Emamectin benzoate (Denim®) is a macrocyclic lactone insecticide/acaricide applied to control the bollworm/budworm complex, fall armyworms, beet armyworms, loopers and spider mites (Tetranychidae) in cotton. It is applied at 0.0075 to 0.015 lb ai per acre. The restricted-entry interval is 48 hours is and the preharvest interval is 21 days. Emamectin benzoate also controls pink bollworm when applied at 0.01 to 0.0125 lb ai per acre at 4-day intervals after infested bolls reach thresholds. Applications occur in the Texas High Plains and Trans Pecos regions and are limited to fields where at least 5% of the cotton is infested with pink bollworm larvae or where other techniques (mating disruption and use of Bollgard® cotton) have failed to keep infestation levels below economic thresholds.

Endosulfan (Thiodan®®, Phaser ) Endosulfan (Thiodan®®, Phaser ) chlorinated cyclodiene insecticide is applied for control of whiteflies and boll weevils at rates of 0.375 to 1.5 lb ai per acre. Applications for boll weevils include overwintered and in-season boll weevils and occur by ground and air, with more being done by air. Applications for control of Bemisia (silverleaf and sweetpotato) whiteflies generally include a tank mix of endosulfan with a pyrethroid. These combinations have provided superior control of whiteflies in efficacy studies conducted in the Lower Rio Grande Valley. Endosulfan may be applied until the first bolls begin to open. Applications of endosulfan in any one season may not exceed 3.0 lb ai per acre. The restricted entry interval

55 is 24 hours. The pre-harvest interval for cotton is not specified on the label, but no applications may be made after bolls are open.

Esfenvalerate (Asana®) Esfenvalerate (Asana XL® 0.66 EC) is used moderately to control bollworms, boll weevils, pink bollworms, Lygus and Creontiades plant bugs, saltmarsh caterpillars, and grasshoppers at rates of 0.03 to 0.05 lb ai per acre However, it is not recommended for tobacco budworm. Applications are made by ground and air. The majority of bollworm applications are made by air and usually occur to non-Bt cotton. Boll weevil applications occur by ground and air, with slightly more occurring by air. However, application intervals similar to those recommended for the traditional phosphate insecticides (3 to 5 days under heavy pressure) are necessary to provide adequate control of boll weevils. When treatments are to be made for both bollworms and boll weevils, a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate or carbamate boll weevil insecticide. Since pyrethroids are not more effective than phosphates or carbamates for boll weevil control, but are more effective for bollworm control, they should be reserved for bollworm management. Extension insecticide guides for cotton do not recommend using pyrethroids for boll weevil control alone or for early season pests because increased use may enhance the opportunity for insects to develop resistance to pyrethroids.

Early use of pyrethroids also is not recommended because of their tendency to release or cause resurgence of secondary pests, such as aphids, spider mites and whiteflies. Applications of esfenvalerate for grasshoppers occur occasionally early in the season, when local outbreaks threaten stands in some fields. Similarly, applications for cutworms and saltmarsh caterpillars occur early in the season, primarily in non-Bt cotton or in cotton that has not yet begun to express the Bt toxin sufficiently enough to give control. They are made by air and ground, with about equal numbers applied by each method. Applications for pink bollworm control usually occur in the Texas High Plains and Trans Pecos Regions. They most often take place after bloom when pink bollworm infestation levels exceed 5% of susceptible bolls or where other techniques (mating disruption and use of Bt cotton) have failed to keep infestation levels below economic thresholds. The preharvest interval is 21 days. The restricted-entry interval is 12 hours. Although registered for stink bugs, Extension guides do not recommend the use of esfenvalerate for stink bugs.

Fenpropathrin (Danitol®) Fenpropathrin effectively controls silverleaf and sweet potato whiteflies (Bemisia argentifolii and B. tabaci) at rates of 0.8 lb ai per acre only when mixed with acephate. Efficacy studies have shown that fenpropathrin does not effectively control whiteflies when applied by itself but must be mixed with acephate to achieve consistent control. However, it also is effective when mixed with neonicotinoids (acetamiprid, imidacloprid, thiacloprid), nitroguanadines (thiamethoxam: Actara®®), or the IGR pyriproxyfen (Knack ). Fenpropathrin is also effective against spider mites (Tetranychidae) at rates of 0.2 to 0.3 lb ai per acre. Although fenpropathrin is registered for control of additional cotton pests, such as beet armyworm, cotton bollworm, tobacco budworm, pink bollworm, Lygus bugs, saltmarsh caterpillars, Western flower thrips and spider mites, it is not recommended for control of these pests in Extension insecticide guides because of its lack of demonstrated efficacy. Fenpropathrin is not used in Eastern, Southern and Gulf Coast production areas.

Gossyplure (Checkmate PBW®®, No Mate PBW , PB Rope L®) Gossyplure is a two component pheromone product composed of a 50:50 blend of the Z,Z and Z,E isomers of 7,11-hexadecadien-1-ol acetate. It is applied for mating disruption of pink bollworm (Pectinophora gossypiella) in non-Bt upland cotton and in Pima cotton. It is applied in controlled-release formulations, which include sprayable nylon and PVC microcapsules (Checkmate PBW®, membrane dispensers, open-ended, hollow nylon fibers (No Mate PBW®®), and sealed polyethylene tubes (PB Rope and PB Rope L®).

56 Sprayable formulations require resin or latex stickers to hold them to plant surfaces and are applied by both ground and aerial application equipment. Fiber formulations are applied exclusively by air with a special fiber dispenser in which fibers are mixed with an adhesive to fix them to plant surfaces. Polyethylene tube and membrane dispensers are applied by hand at the rate of 400 per acre. When applied to fields, controlled-release dispensers release gossyplure for various periods extending from 14 days (microcaps) to full-season (PB Rope L®) at the approximate rate of 160 micrograms per day. Its use has been steadily increasing in the Trans Pecos region since the first mating disruption experiments were conducted in 1989. Use declined slightly with widespread planting of Bt cotton varieties in the Pecos Valley, which provided direct control of pink bollworm larvae. However, with the onset of pink bollworm eradication, applications of gossyplure increased significantly in the Trans Pecos regions, first with aerial application of No Mate® fibers and later as with hand application of PB Rope L® dispensers. Its potential for mating disruption of pink bollworm in non-Bt upland varieties and in Pima cotton will not diminish until pink bollworm has been eradicated. Early and late-season gossyplure applications (clearly targeted at pink bollworm) fit resistance management strategies for the bollworm/budworm complex, plant bugs, cotton aphid and silverleaf whitefly where these pests occur with pink bollworm in non-Bt upland and Pima cotton. The restricted entry interval is 4 hours. The pre-harvest interval is 0 days.

Imidacloprid (Gaucho Grande®®, Leverage , Provado®, Trimax®) Imidacloprid (Gaucho Grande®) neonicotinoid insecticide is applied as a seed treatment to delinted cotton seed to control thrips and cutworms at the rate of 4.8 to 8 ounces of product per 100 pounds of seed. Imidacloprid (Leverage®®, Provado , Trimax®) is applied to early squaring cotton for fleahoppers, Lygus and Creontiades plant bugs. Imidaclprid (Provado® 1.6 F, Trimax® 4 SC) is applied to early and mid-season growth stages for aphids, grasshoppers and saltmarsh caterpillars. It is applied mid-season to late season for cotton bollworms, and boll weevils but is not recommended for tobacco budworms or pink bollworms. Applications of a mixed formulation of imidacloprid and cyfluthrin (Leverage® 2.7 SE) are made for bollworms. The mixed formulation is applied at the rate of 0.032 lb ai imidacloprid + 0.047 lb ai cyfluthrin per acre. The restricted-entry interval is 12 hours and the preharvest interval is 14 days. Imidacloprid applications are made with both ground and aerial equipment with aerial applications predominating. Application rates The preharvest interval is 14 days. Mid-season and late-season applications of imidacloprid are made for control of stink bugs. Although beet armyworm, loopers and spider mites also occur on the label, imidacloprid is not recommended for control of these pests in Texas cotton. The relatively high price of imidacloprid products has resulted in its limited use compared to other insecticides.

Indoxacarb (Steward®) Indoxacarb oxadiazine insecticide is applied at the rate of 0.09 to 0.11 lb ai per acre for control of Lygus bugs, the cotton bollworm/tobacco budworm complex, beet armyworm and loopers in the Eastern, Southern and Blacklands areas of Texas. In the Texas High Plains, Rolling Plains and Trans Pecos regions, it is recommended for control of fleahoppers, the bollworm/budworm complex, beet armyworms and loopers, but is not recommended for Lygus bugs. In the Lower Rio Grande Valley, it is applied for control the bollworm/budworm complex and beet armyworm, but not for loopers or plant bugs. It is effective against the previously named Lepidoptera and its primary use is in non-Bt cotton. Indoxacarb also has demonstrated activity against tarnished plant bug in the Eastern, Southern and Blacklands regions of Texas but not in the regions of West Texas. Although it is not recommended for use against plant bugs as a primary target pest, this is an important advantage when growers need to control mixed infestations of caterpillars and tarnished plant bugs. Although registered for control of cotton fleahopper and recommended in Extension insecticide guides, indoxacarb is seldom used to control this pest due to expense and the availability of more effective products. Although indoxacarb has demonstrated efficacy against beet armyworm, lack of efficacy data for fall armyworm prevent its recommendation for control of this pest. The restricted-entry interval is 12 hours, and the preharvest interval is 14 days.

57 Lambda-Cyhalothrin (Karate®®, Warrior ) Lambda-cyhalothrin (Karate®®, Warrior ) synthetic pyrethroid insecticide is applied at rates of 0.025 to 0.04 lb ai per acre to control cutworms, Lygus bugs, stink bugs, bollworm larvae and boll weevils, but not tobacco budworm larvae. Bollworm/boll weevil applications are made by ground and air with a larger percentage being applied by air. It is widely used for bollworm control. Approximately 0.5 to 2 applications are made each growing season on Bollgard®® cotton and 2 to 5 applications per growing season on non-Bollgard cotton. Lambda-cyhalothrin will effectively control boll weevil, but application intervals similar to those recommended for the traditional phosphate insecticides (3 to 5 days under heavy pressure) are necessary to do it adequately. When treatments are to be made for a bollworm-boll weevil complex a suggested treatment regime is to use a pyrethroid followed 3 to 5 days later by a phosphate or carbamate boll weevil insecticide. Since pyrethroids are not more effective than phosphates or carbamates for boll weevil control, but are more effective for bollworm control, they should be reserved for bollworm management.

Extension insecticide guides for cotton do not recommend using pyrethroids for boll weevil control alone or for early season pests because increased use may enhance the opportunity for insects to develop resistance to pyrethroids. Early use of pyrethroids also is not recommended because of their tendency to release or cause resurgence of secondary pests, such as aphids, spider mites and whiteflies. Boll weevil applications are made by ground and air with a larger percentage being applied by air. In the Texas High Plains and Trans Pecos regions, lambda-cyhalothrin is also applied to control pink bollworms when infestation levels exceed 5% of susceptible bolls or where other techniques (mating disruption and use of Bollgard® cotton) have failed to keep infestation levels below economic thresholds. The preharvest interval is 21 days. The restricted-entry interval is 24 hours.

Malathion (Fyfanon®) Malathion ULV (Fyfanon®) is registered for use against fleahoppers, Lygus and other plant bugs (Miridae) and boll weevil. Its primary use is against boll weevil in eradication programs and in diapause control programs. The use of malathion ULV for boll weevil control provides some secondary control of plant bugs. Boll weevil ULV applications are made by ground and air. However, nearly 100% of the applications of ULV malathion for boll weevil occur by air. Application rates average 10 ounces per acre by air and 16 ounces per acre by ground equipment. The preharvest interval is 0 days. The restricted-entry interval is 12 hours.

Methamidophos (Monitor®) Methamidophos is registered for fleahoppers, Lygus and other plant bugs (Creontiades spp., Hemiptera: Miridae). Methamidophos applied at 0.25 to 0.5 lb ai per acre may be occasionally used for controlling plant bugs on a small percentage of cotton acres. The preharvest interval is 50 days. The restricted-entry interval is 48 hours.

Methomyl (Lannate®) Methomyl (Lannate®® SP and Lannate LV) oxime carbamate insecticide is applied as an ovicide/larvicide for the bollworm/budworm complex. It is also applied for control of cotton fleahopper, Lygus and Creontiades plant bugs and aphids. Bollworm applications are made by ground and air with the majority applied by air. Application rates as an ovicide for bollworm and budworms eggs and as a bollworm larvicide are between 0.113 and 0.225 lb ai per acre. Ovicidal applications are never recommended without the presence of bollworm or budworm larvae. Applications for the bollworm/budworm complex are made by ground and air with the majority being applied by air. The rates for control of cotton fleahopper and aphids also are 0.113 and 0.225 lb ai per acre. Rates for Lygus and Creontiades plant bugs are 0.225 lb ai per acre. For hard to kill pests, such as tobacco budworm larvae and beet armyworm, methomyl is applied at 0.45 lb ai per acre. Methomyl can play an important role in plant bug resistance management because the oxime carbamate insecticides differ substantially from organophosphate, neonicotinoid and synthetic pyrethroid insecticides used for plant bug and aphid control. The preharvest interval is 15 days. The restricted-entry

58 interval is 72 hours. Methomyl is declining because of widespread planting of Bt cotton and competition from more effective insecticides for Lepidoptera larvae. When applied at higher label rates, methomyl has a tendency to cause mild phytotoxicity (reddening of leaves), which is another factor that limits its use. Although registered for use against fall armyworm and thrips, lack of efficacy data prevents its recommendation for control of these pests in Extension insecticide guides for cotton.

Methoxyfenozide (Intrepid®) Methoxyfenozide (Intrepid® 2F) insect growth regulator (IGR) is applied in East and South Texas and the Blacklands regions for the control of the bollworm/budworm complex and at 0.06 to 0.16 lb ai per acre for leaf feeding Lepidoptera, such as beet armyworm and cabbage looper. It is applied by ground and air at the rates of 0.25 to 0.38 lb ai per acre. In the High Plains, Rolling Plains and Trans Pecos Regions, it is applied for beet armyworms and loopers but is not recommended for bollworm control. In the Lower Rio Grande Valley, methoxyfenozide is applied for control of the bollworm/budworm complex and for beet armyworm. Its use is primarily in non-Bt cotton and in Bt cotton in which expression of the Bt endotoxin is insufficient to provide control of caterpillars, armyworms and the bollworm/budworm complex. Although the current lines of transgenic Bt cotton, which express the Cry1Ac endotoxin, provide limited suppression of beet armyworms, Bt cotton can be damaged by beet armyworms and supplemental methoxyfenozide treatments may be required to control beet armyworms in Bt fields. The pre-harvest interval is 14 days. The restricted entry interval is 4 hours.

Methyl parathion (Methyl Parathion, Penncap-M®) Methyl parathion is applied early in the season for control of cutworms and thrips at rates of 0.125 to 0.25 lb ai per acre. It may be applied at 0.1 to 0.25 lb ai per acre during early squaring to boll set for control of fleahoppers, Lygus and other plant bugs (Creontiades spp., Hemiptera: Miridae). Aphid control requires applications of 0.25 to 0.375 lb ai per acre. Widespread to reports of its failure to control aphid populations has been reported because of resistance to organophosphates resulting from overtranscription of non-specific esterase genes in aphid populations. In the Lower Rio Grande Valley, it is applied for spider mite control at 0.25 lb ai per acre and for control of the bollworm/budworm complex at 1.25 to 2.0 lb ai per acre. Applications for bollworms and budworms are becoming less frequent with increasing acreages planted to Bt-cotton. Applications for overwintered and in-season boll weevils occurs at rates between 0.92 and 1.22 lb ai per acre. However, with statewide implementation of boll weevil eradication these applications continue to decline in number. Applications are made by ground and air with a larger percentage being applied aerially. It also is applied for control of stink bugs at 0.5 to 1.0 lb ai per acre. In the Texas High Plains and the Trans Pecos regions, methyl parathion is also applied for control of pink bollworm at the rates of 0.5 to 1.0 lb ai per acre. Applications occur primarily in fields where at least 5% of the cotton is infested with pink bollworm larvae or where other techniques (mating disruption and use of Bt cotton) have failed to keep infestation levels below economic thresholds. The preharvest interval is 7 days. The restricted-entry interval is 48 hours.

Oxamyl (Vydate®) Oxamyl (Vydate®® L and Vydate C-LV) oxime carbamate insecticide is applied for fleahoppers, Lygus and other plant bugs (Miridae). Applications are made by ground and air with about the amount of applications split about equally between the two methods. Application rates are at 0.25 lb ai per acre. It is applied for boll weevil at the same rate, with the majority of applications occurring by air. From squaring to late boll set, oxamyl may be applied for stink bug control at rates between 0.33 and 0.5 lb ai per acre. The preharvest interval for Vydate C- LV is 14 days. The preharvest interval for Vydate L is 21 days. The restricted-entry interval for both products is 48 hours. Oxamyl can play an important role in plant bug resistance management because the oxime carbamate insecticides differ substantially from organophosphate, neonicotinoid and synthetic pyrethroid insecticides used for plant bug control. It also can provide secondary nematode control when both pests are in

59 the field. Oxamyl is very efficacious and cost effective, especially when both plant bugs and nematodes are present.

Phorate (Thimet®) Phorate (Thimet® 20G) is applied in furrow at planting for control of thrips. Applications may be made only once per season at rates of 0.5 to 1.64 lb ai per acre by ground equipment. The restricted entry interval is 72 hours. The pre-harvest interval is 60 days. Phorate may also be applied occasionally as a safener when used in conjunction with clomazone (Command®) herbicide applied PPI or PRE. Clomazone by itself can kill cotton. If it is to be used, either disulfoton or phorate insecticides must be used in-furrow at planting. Clomazone labels require the application of labeled rates of phorate or disulfoton at planting to provide safening from phytotoxicity. However, when used on cotton at the maximum recommended rates under adverse conditions such as extremely cool or wet or extremely dry weather, phorate may cause some delay in emergence, stunting of seedlings, or reduction of stand. Damage may be more pronounced in light, sandy soils. Plant injury may also occur when phorate is applied in conjunction with certain pre-emergent herbicides containing diuron.

Profenofos (Curacron®) Profenofos (Curacron® 8E) is applied as an ovicide larvicide for control of the bollworm/budworm complex. Ovicidal applications are not recommended when larvae are not also present. Applications for bollworm are made by ground and air with the majority being applied by air. It is applied at 0.5 lb ai per acre. The high cost of treatments and the availability of more effective caterpillar insecticides has usually limited applications to less than 1 percent of total acreage. However, because profenofos is activated more efficiently by resistant budworms, bollworms and armyworms, it has historically been used when other insecticides, particularly when synthetic pyrethroids have failed due to resistance. The number of applications are declining because of widespread planting of Bt-cotton. Profenofos is applied at the rates of 0.25 to 0.75 lb ai per acre to suppress aphids and spider mites. Profenofos is also applied for the control of beet armyworm at 0.75 to 1.0 lb ai per acre. Presently, the principal value of profenophos is that it is an economical choice for use against mixed populations of bollworms, plant bugs, armyworms and building populations of aphids and/or spider mites. Although profenofos labels include cotton fleahopper, Lygus and other plant bugs, it is not recommended in any of the Extension insecticide guides for cotton because of the lack of demonstrated efficacy and the availability of more effective products. The preharvest interval is 30 days. The restricted-entry interval is 48 hours in regions with more than 25 inches of rainfall and 72 hours in regions with less than 25 inches of rainfall.

Propargite (Comite®) Propargite (Comite®) is applied exclusively for the control of spider mites (Tetranychidae). It is applied at rates of 0.8 to 1.6 lb ai per acre. Although no documented cases of resistance to propargite have been documented in more than 40 years since it was first registered, it is advisable to avoid the use of reduced rates and to use propargite only once or twice in a given season because individual spider mites differ in their tolerance to this acaricide. Two factors mitigate against the efficacy of propargite to reduce spider mite populations. It is comparatively slow in producing mortality, and in times when average daytime temperatures exceed 85 degrees, mites are able to lay eggs before they die. Propargite has no ovicidal effects, and eggs laid before mortality usually hatch and replace the individuals killed. A second factor affecting the efficacy of propargite is that mite infestations usually occur on the undersides of cotton leaves. Control usually fails when applications occur by air or by ground equipment not equipped to giver coverage on the undersides of leaves. Best control comes from ground equipment with drop nozzles directed to give coverage under leaves. Resistance management practices should include rotation of chemical classes when making treatments for spider mites in cotton. Comite also kills predatory mites but is comparatively inactive against insects that prey on mites. Resurgence of mite populations after treatment with avermectin are not likely in cotton when insect mite predators are present. Comite is an effective acaricide but rarely used because spider mite outbreaks in cotton usually occur

60 during the hottest part of the summer, which is the time of year propargite is least effective. The restricted entry interval is 7 days. An exception to the REI is made for workers who may enter the treated area 48 hours after an application if they wear early entry personal protective equipment specified on the label. The pre-harvest interval is 50 days.

Pyriproxyfen (Knack®) Pyriproxyfen (Knack®) is registered for control of Bemisia whiteflies (B. argentifolii and B. tabaci) applied by ground or air at rates of 0.054 to 0.067 lb ai per acre. Because no whitefly outbreaks have occurred since the early 1990s, the lack of efficacy data from Texas prevents the recommendation of this insecticide in Extension guides.

Spinosad (Tracer®) Spinosad (Tracer® 4SC) spinosyn bioinsecticide is applied for control of beet armyworm and the bollworm/budworm complex. Spinosad is a fermentation product of the actinomycete Saccharopolyspora spinosa. Bollworm applications occur by ground and air with the most applied by air. Spinosad is a comparatively new insecticide used solely to control Lepidoptera larvae. It gives good control of bollworm, tobacco budworm, most caterpillars, loopers and armyworms, which makes it important in production of non-Bt cotton and cotton in which environmental factors may have reduced the expression Bt toxin. Applications occur primarily to non-Bt cotton and in Bt cotton in which expression of the Bt endotoxin is insufficient to provide control of caterpillars, armyworms and the bollworm/budworm complex. Although the current lines of transgenic Bt cotton, which express the Cry1Ac endotoxin, provide limited suppression of beet armyworms, Bt cotton can be damaged by beet armyworms and supplemental spinosad treatments may be required to control beet armyworms in Bt fields. Use rates range from 0.067 to 0.089 lbs ai per acre. Spinosad is relatively benign to many beneficial insects, but there are some key beneficial species that are quite susceptible to spinosad. The restricted-entry interval is 4 hours. The preharvest interval is 28 days. Spinosad is also registered for pink bollworm control at 0.063 lb ai per acre, applied at 4-day intervals after infested bolls reach thresholds. However, lack of efficacy data for the High Plains and the Trans Pecos regions prevents its recommendation in Extension insecticide guides.

Tebufenozide (Confirm®) Tebufenozide (Confirm®) insect growth regulator is applied at the rate of 0.125 to 0.25 lb ai per acre to cotton to control beet armyworm, fall armyworm and cabbage looper. The restricted entry interval is 4 hours. The pre-harvest interval is 14 days.

Thiamethoxam (Centric®®, Cruiser ) Thiamethoxam (Centric® 25 WG or 40 WG) neonicotinoid insecticide is applied at rates of 0.047 lb ai per acre for the control of thrips, aphids and fleahoppers. Applications are made with both ground and aerial equipment. If seed was treated with thiamethoxam, foliar applications of neonicotinoid insecticides, including thiamethoxam may not be made until 45 days after planting. Because it provides good control of thrips, aphids and plant bugs and is reasonably priced, the relative use and importance of thiamethoxam is likely to increase. Thiamethoxam is also labeled for the control of Lygus bugs and whiteflies at 0.047 lb ai per acre but is not recommended in Extension guides because there is not yet sufficient efficacy data to support recommendations. Applications of thiamethoxam in any one season may not exceed 0.094 lb ai per acre. The restricted entry interval is 12 hours. The pre-harvest interval is 21 days.

As a seed treatment, thiamethoxam (Cruiser® 5 FS) is applied to delinted cotton seed at the rate of 0.303 lb ai (7.75 fl oz Cruiser® 5FS) per 100 pounds of seed to control thrips and aphids in seedling cotton. This relatively new product provides effective control of thrips for two to three weeks following emergence. In areas that have a history of high thrips pressure seed with thiamethoxam treatment may require a subsequent foliar treatment with a non-neonicotinoid insecticide when cotton is between the 1st and 3rd leaf stage.

61 Thiamethoxam seed treatments also control cotton aphids on seedling cotton, which means that its use is likely to increase in the near future. Forty-five days must elapse after planting cotton seed treated with thiamethoxam before subsequent applications of neonicotinoid insecticides may be made to the crop. The restricted entry interval is 12 hours and the pre-harvest interval is not addressed on the seed treatment label.

Thiodicarb (Larvin®) Thiodicarb (Larvin®) heterocyclic carbamate insecticide is applied as an ovicide/larvicide for control of eggs and larvae of the bollworm/budworm complex. Ovicidal rates are 0.125 to 0.25 lb ai per acre, but applications are not recommended without accompanying larval infestations. The application rates for bollworm and budworm larvae are 0.6 to 0.9 lb ai per acre. Thiodicarb also effectively controls beet armyworm. Applications are made by ground and air with the majority applied by air. It is also labeled for control of cutworms, loopers and fall armyworm, but is not recommended for these pests in Extension insecticide guides due to insufficient efficacy data. The use of thiodicarb is declining because of widespread planting of Bt cotton and availability of newer insecticides for Lepidoptera larvae. Presently applications occur in non-Bt cotton or in cotton in which the expression of the Bt toxin has proved insufficient to suppress bollworms, budworms and armyworms. Thiodicarb is not 'rain fast' and requires several rain free/irrigation free days for maximum efficacy. This lack of rain fastness is another factor that limits its use. The restricted-entry interval is 12 hours. The pre-harvest interval is 28 days.

Tralomethrin (Scout X-tra®) Tralomethrin (Scout X-tra®) synthetic pyrethroid insecticide is applied at 0.016 and 0.02 lb ai per acre for the control of Lygus bugs, stink bugs, cutworms, saltmarsh caterpillar cotton bollworm and pink bollworm larvae. Application methods include air and ground with more occurring by air. The use of tralomethrin is declining and is expected to continue because of extensive planting of Bt cotton, the availability of more effective insecticides, and possible discontinuation of the product by the manufacturer. The preharvest interval is 28 days. The restricted-entry interval is 24 hours.

Zeta-Cypermethrin (Fury®®, Mustang Max ) Zeta-cypermethrin (Fury®® 1.5 EC, Mustang Max ) synthetic pyrethroid insecticide is applied for control of the bollworm/budworm complex, boll weevils, grasshoppers, cutworms, saltmarsh caterpillars, Lygus bugs, Creontiades plant bugs, stink bugs, and pink bollworm. The Mustang Max 0.8 lb ai per gallon formulation of enriched active isomers of zeta-cypermethrin has replaced the Fury® 1.5 EC formulation, which has practically disappeared from pesticide inventories. The use rates for Mustang Max® range from 0.008 to 0.025 lb ai per acre. Applications are made by ground and air with a larger percentage applied by air. The majority of zeta-cypermethrin applications are to non-Bt cotton or pests that are not controlled by Bt cotton. These include grasshoppers, Lygus bugs and stink bugs. Some cotton acres receive an application of zeta-cypermethrin each year to control larvae of the bollworm/budworm complex, boll weevil and pink bollworm. However, with extensive planting of Bt cotton, use has declined significantly for these pests. Because pyrethroids are not more effective than phosphates or carbamates for boll weevil control, but are more effective for bollworm control, Extension insecticide guides suggest reserving them for bollworm and budworm management.

Extension guides do not recommend pyrethroids for boll weevil control alone or for early season pests because increased use may enhance the opportunity for insects to develop resistance to pyrethroids. Early use of pyrethroids also is not recommended because of their tendency to release or cause resurgence of secondary pests, such as aphids, spider mites and whiteflies. The extensive planting of Bt cotton and the eradication of boll weevil may see a change in use patterns of zeta-cypermethrin and other synthetic pyrethroids, including early season applications for grasshoppers, Lygus bugs, other plant bugs and stink bugs. The preharvest interval is 14 days. The restricted-entry interval is 12 hours.

62 Weed Control

Controlling weeds in cotton in Texas is one of the most critical aspects of successful lint production. Unchecked weed populations can rob valuable moisture and nutrients from the crop as well as cause significant quality reductions at harvest. One of the most critical challenges in cotton weed control is to provide the seedling cotton plant with conditions that allow the crop to outgrow weeds, thus providing a height differential for directed sprays. Recent technological advancements have changed many aspects of weed control in cotton but challenges are ever present.

Approximately 60-70 percent of Texas cotton acres are planted to herbicide-tolerant varieties. The Roundup Ready and Liberty Link systems are the predominant weed control programs employed. In some cases, the utilization of herbicide-tolerant cotton varieties has allowed producers to increase yield and quality of the cotton produced.

However, the use of herbicide-tolerant cotton varieties has not provided a ‘cure-all’ for weed control in cotton. Issues such as narrow herbicide application windows, weed species population shifts and resistance, and rising technology fees have caused some producers to limit their use of herbicide-tolerant varieties. Recently, it has become difficult for cotton producers to acquire conventional planting seed as seed companies continue moving towards transgenic varieties. In the face of rising energy costs, potential changes in government subsidies, and a fluctuating world cotton market, cotton producers are left with fewer options to reduce their inputs.

The Roundup Ready system has had the greatest level off adoption by Texas cotton producers. However, the number of acres of Liberty Link cotton planted in 2005 are expected to rise significantly as some cotton producers look for more flexibility in application timing. Currently, Roundup Ready cotton varieties cannot be sprayed over-the-top with glyphosate past the four-leaf stage. The release of Roundup Flex cotton varieties in 2006 should allow greater flexibility for over-the-top glyphosate applications.

Herbicide-tolerant cotton varieties have allowed many growers to decrease their use of residual herbicides. As a result, weed species population shifts towards glyphosate-tolerant weeds are occurring throughout cotton growing regions. Another result is the increased occurrence of escapes, or weeds that were not present or adequately covered by spray solution at the time of application.

Common annual grasses found in cotton include barnyardgrass (Echinochloa crus-galli), southern or large crabgrass (Digitaria spp.), junglerice (Echinochloa colona), browntop panicum (Panicum fasciculatum), Texas panicum (Panicum texanum), broadleaf signalgrass (Brachiaria platyphylla), and various sprangletops (Leptochloa spp.). Johnsongrass (Sorghum halapense) and bermudagrass (Cynodon dactylon) are common perennial grass weeds.

Common monocot weeds found in cotton are yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus).

Annual broadleaf weeds include many members of the sunflower family such as common sunflower (Helianthus annuus), cocklebur (Xanthium strumarium), golden crownbeard (Verbesina encelioides), and eclipta (Eclipta prostrata). Some of the smaller-seeded annual broadleaf weeds include the pigweeds and amaranths, such as Palmer amaranth (Amaranthus palmeri), tumble pigweed (Amaranthus albus), smooth pigweed (Amaranthus hybridus), spiny pigweed (Amaranthus spinosus), redroot pigweed (Amaranthus retroflexus), and common waterhemp (Amaranthus rudis).

63 Other common small-seeded annual broadleaf weeds include common lambsquarter (Chenopodium album), kochia (Kochia scoparia), Russian thistle (Salsola iberica), common purslane (Portulaca oleracea), and knotweed (Polygonum spp.). Larger seeded weeds include various morningglories (Ipomoea spp.), sesbania (Sesbania spp.), sicklepod (Senna obtusifolia), hophornbeam copperleaf (Acalypha ostryifolia), prostrate spurge (Euphorbia prostrata), devil’s claw (Proboscidea louisianica), Mexicanweed (Caperonia castaniifolia), and smellmelon (Cucumis melo).

Perennial broadleaf weeds include Texas blueweed (Helianthus ciliaris), silverleaf nightshade (Solanum elaeagnifolium), sharppod morningglory (Ipomoea cordatotriloba), and field bindweed (Convolvuvis arvensis).

Brief descriptions of common herbicides are listed with classification and application rate information summarized in corresponding tables. Also in table format are plant growth regulator and harvest aid products commonly used in Texas cotton production.

64 Herbicides

Herbicides applied post-harvest or pre-plant to control winter weeds

Glyphosate (Roundup®) There are numerous trade names and formulations, the oldest of which is Roundup®. Glyphosate is commonly used after harvest of the previous crop and/or before planting the current crop to control unwanted broadleaf and grass weeds. It is commonly tank-mixed with other herbicides such as 2,4-D to improve the spectrum of control.

Oxyfluorfen (Goal®) Oxyfluorfen (Goal®) provides both postemergence and preemergence activity on primarily broadleaf weeds. Commonly tank-mixed with glyphosate or other postemergence herbicides to provide residual weed control during fallow period.

2,4-D (Formula 44®®, Weedone , Weedar®) Many different manufacturers and formulations and trade names, among which are Formula 44®®, Weedone and Weedar®. Provides a cost effective method for chemical cotton stalk destruction and seedling cotton control in boll weevil eradication zones. 2,4-D is also used for fallow period broadleaf weed control. Commonly tank-mixed with glyphosate.

Prometryn (Caparol®®, Cotton Pro , Prometryne®) Trade names include Caparol®®, Cotton Pro , and Prometryne. Provides preemergence control of many annual grasses and broadleaf weeds. May be tank-mixed with post- emergence herbicide to provide control of emerged weeds.

Pre-plant herbicides applied to control emerged weeds

Glyphosate (Roundup®) There are numerous trade names and formulations, the oldest of which is Roundup®. Provides broad-spectrum control of many broadleaf and grass weeds prior to planting. It is commonly tank-mixed with other herbicides such as 2,4-D to improve the spectrum of control.

MSMA Several trade names are available. Generally tank-mixed with other postemergence herbicides to improve spectrum of control. Alone, MSMA provides control of many grasses and sedges.

Paraquat (Gramoxone®) Trade name is Gramoxone Max®. Provides non-selective control of broadleaf and grass weeds. Paraquat is a contact herbicide that only controls vegetation covered by spray solution and has no residual activity.

Thifensulfuron + Tribenuron (Harmony Extra®) Trade name is (Harmony Extra®). This herbicide is a pre-mix of two sulfonylurea herbicides. Provides postemergence control of several broadleaf weeds. Applications must be made 14 days prior to planting cotton.

2,4-D (Formula 44®®,Weedone , Weedar®) With many different manufacturers and formulations, including Formula 44®®, Weedone and Weedar®, 2,4-D controls many broadleaf weeds and is often tank-mixed with glyphosate.

Glufosinate (Ignite®) Trade name is Ignite®. Provides broad-spectrum control of many broadleaf and grass weeds. Glufosinate causes rapid contact-like symptoms on susceptible species.

65 Pre-plant incorporated (PPI) herbicides

Norflurazon (Zorial Rapid®) Trade name is Zorial Rapid®. Provides control of many annual grasses in cotton. PPI use is restricted to cotton growing regions east of I-35.

®®® Pendimethalin (Prowl , Prowl H2O , Pendimax ) ®® ® Trade names are Prowl , Prowl H2O , and Pendimax . Provides control of many annual grasses as well as pigweed, purslane, and lambsquarter.

Trifluralin (Treflan®®, Trilan ) There are several different trade names, the best known of which is Treflan®. Provides control of many annual grasses as well as pigweed, purslane, and lambsquarter. Trifluralin should be incorporated immediately after application.

Pre-plant incorporate/ preemergence (PRE) herbicides

Norflurazon (Zorial Rapid®) Trade name is Zorial Rapid. Provides control of many annual grasses in cotton. Can be applied as PRE only in cotton growing regions west of I-35.

Trifluralin (Treflan®®, Trilan ) There are several different trade names the oldest and best know of which is Treflan®. Provides control of many annual grasses as well as pigweed, purslane, and lambsquarter. In irrigated areas, trifluralin is applied via chemigation.

Pendimethalin (Prowl®®, Prowl H2O , Pendimax®) ®® ® Trade names are Prowl , Prowl H2O , and Pendimax . Provides control of many annual grasses as well as pigweed, purslane, and lambsquarter.

Preemergence herbicides

Diuron (Karmex®®, Direx ) Trade names include Karmex®®, Direx , and Diuron. Applications are commonly tank-mixed with other herbicides such as pendimethalin. Diuron controls many annual broadleaf and grass weeds.

Fluometuron (Cotoran®) Trade name is Cotoran®. Controls many broadleaf and grass weeds. Applications are commonly tank-mixed with other herbicides such as pendimethalin.

S-Metolachlor (Dual Magnum®®, Dual II Magnum , Cinch®) Trade names are Dual Magnum®®, Dual II Magnum and Cinch®. Provides control of many annual grass weeds and yellow nutsedge.

Norflurazon (Zorial Rapid®) Trade name is Zorial Rapid®. Provides control of many annual grasses in cotton. Can be applied as PRE only in cotton growing regions west of I-35.

Prometryn (Caparol®®, Cotton Pro , Prometryne®) Trade names include Caparol®®, Cotton Pro , and Prometryne. Provides preemergence control of several annual grasses and broadleaf weeds.

Pyrithiobac (Staple®) Trade name is Staple®. Provides control of broadleaf weeds including some morningglory species and susceptible pigweeds. Commonly applied in a band due to cost considerations.

66 Clomazone (Command®) Trade name is Command®. Provides control of many grasses and certain broadleaf weeds. Cotton treated with clomazone must have been safened by application of disulfoton or phorate insecticide in-furrow.

Postemergence (POST) or post-directed (PDIR) herbicides

Trifluralin (Treflan®®, Trilan ) There are several different trade names, the best known of which is Treflan®. Provides control of many annual grasses as well as pigweed, purslane, and lambsquarter.

Pendimethalin (Prowl®®, Prowl H2O , Pendimax®) ®® ® Trade names are Prowl , Prowl H2O , and Pendimax . Provides control of many annual grasses as well as pigweed, purslane, and lambsquarter.

S-Metolachlor (Dual Magnum®®, Dual II Magnum , Cinch®) Trade names are Dual Magnum®®, Dual II Magnum and Cinch®. Can be applied alone or in a tank-mix combination with glyphosate in a Roundup Ready system to provide residual grass control.

Prometryn (Caparol®®, Cotton Pro , Prometryne®) Trade names include Caparol®®, Cotton Pro , and Prometryne®. Provides control of several annual grasses and broadleaf weeds. PDIR applications are usually tank-mixed with other herbicides.

Fluometuron (Cotoran®) Trade name is Cotoran®. Provides residual control of many broadleaf and grass weeds when applied PDIR in cotton.

Diuron (Karmex®®, Direx ) Trade names include Karmex®®, Direx , and Diuron. Provides residual control of many broadleaf and grass weeds when applied PDIR in cotton.

Lactofen (Cobra®) Trade name is Cobra®. Provides control of several broadleaf weeds. Generally tank-mixed with other herbicides to improve spectrum of control.

DSMA There are several trade names. Post-directed applications of DSMA are generally tank- mixed with other herbicides to improve control of grasses and some broadleaves.

MSMA There are several trade names. Post-directed applications of MSMA are generally tank- mixed with other herbicides to improve control of grasses and some broadleaves.

Pyrithiobac (Staple®) Trade name is Staple®. Provides control of broadleaf weeds including some morningglory species and susceptible pigweeds. Pyrithiobac is commonly tank-mixed with herbicides such as glyphosate in Roundup Ready systems to provide residual control.

Fluazifop (Fusilade DX®) Trade name is Fusilade DX®. Provides control of many annual and perennial grasses. This herbicide has no broadleaf activity. Repeat applications may be necessary.

67 Fluazifop + Fenoxaprop (Fusion®) Trade name is Fusion®. This pre-mix controls many annual and perennial grasses. This herbicide has no broadleaf activity. Repeat applications may be necessary.

Clethodim (Select®) Trade name is Select®. Clethodim provides good control of annual and perennial grasses. This herbicide has no broadleaf activity. Repeat applications may be necessary.

Quizalofop (Assure II®) Trade name is Assure II®. Quizalofop controls many annual and perennial grasses. This herbicide has no broadleaf activity. Repeat applications may be necessary.

Sethoxydim (Poast Plus®) Trade name is Poast Plus®. Provides control many annual and perennial grasses. This herbicide has no broadleaf activity. Repeat applications may be necessary.

Carfentrazone (Aim®) Trade name is Aim®. Carfentrazone control several broadleaf weeds when applied PDIR in cotton. This product provides no grass control and no residual weed control.

Pyraflufen-ethyl (ET®) Trade name is ET®. Applications are generally tank-mixed with other herbicides to provide control of small grasses and broadleaves.

Flumioxazin (Valor®) Trade name is Valor®. Applications must be tank-mixed with glyphosate in Roundup Ready cotton systems. Provides residual control of many grass and broadleaf weeds.

Linuron + Diuron (Layby-Pro®) Trade name is Layby-Pro®. This pre-mix provides control of many grass and broadleaf weeds.

Oxyfluorfen (Goal®) Oxyfluorfen (Goal®) provides both postemergence and preemergence activity on primarily broadleaf weeds. Care should be taken to avoid contact with cotton foliage.

Glyphosate (Roundup®) There are numerous trade names and formulations, the oldest of which is Roundup®.. Provides broad-spectrum weed control in Roundup Ready cotton systems. Commonly tank- mixed with other herbicides to improve residual weed control.

Glufosinate (Ignite®) Trade name is Ignite®. Provides broad-spectrum control of many broadleaf and grass weeds in Liberty Link cotton systems. Glufosinate causes rapid contact-like symptoms on susceptible species.

Bromoxynil (Buctril®) Trade name is Buctril®. Provides control of many grass and broadleaf weeds in BXN cotton systems.

Trifloxysulfuron (Envoke®) Trade name is Envoke®. Provides control of primarily broadleaf weeds and nutsedge. Cannot be applied west of I-35 in Texas.

68 Herbicides applied at layby

Prometryn (Caparol®®, Cotton Pro , Prometryne®) Trade names include Caparol®®, Cotton Pro , and Prometryne. Provides control of several annual grasses and broadleaf weeds.

Linuron + Diuron (Layby-Pro®) Trade name is Layby-Pro®. This pre-mix provides control of many grass and broadleaf weeds.

Diuron (Karmex®®, Direx ) Trade names include Karmex®®, Direx , and Diuron. Provides residual control of many broadleaf and grass weeds when applied at layby in cotton.

Fluometuron (Cotoran®) Trade name is Cotoran®. Provides residual control of many broadleaf and grass weeds when applied at layby in cotton.

MSMA There are several trade names. Applications of MSMA are generally tank-mixed with other herbicides to improve control of grasses and some broadleaves. MSMA alone provides no residual control.

Pyrithiobac (Staple®) Trade name is Staple®. Provides control of broadleaf weeds including some morningglory species and susceptible pigweeds. Pyrithiobac is commonly tank-mixed with herbicides such as glyphosate in Roundup Ready systems to provide residual control.

Carfentrazone (Aim®) Trade name is Aim®. Carfentrazone control several broadleaf weeds when applied at layby in cotton. This product provides no grass control and no residual weed control.

Pyraflufen-ethyl (ET®) Trade name is ET®. Applications are generally tank-mixed with other herbicides to provide control of small grasses and broadleaves.

Flumioxazin (Valor®) Trade name is Valor®. Applications must be tank-mixed with glyphosate in Roundup Ready cotton systems. Provides residual control of many grass and broadleaf weeds.

Glyphosate (Roundup®) There are numerous trade names and formulations, the oldest of which is Roundup®. Commonly tank-mixed with other herbicides to improve residual weed control.

*Cotton harvest aid chemicals and plant growth regulators commonly used are summarized in tables 30 and 31.

69 Cotton Disease Control

Seedling diseases

Cotton seedling diseases are the first ones a producer sees each year. They kill or stunt young seedling plants and cause large skips in cotton stands. Seedling diseases are caused by a complex of fungi that live in the soil. Symptoms may appear as decay of the seed before germination, decay of the seedling before emergence, girdling of the seedling at or near the soil line, rotting of the root tips or stunted plants with thickened dark colored roots and shoots. Several practices can help to reduce losses to seedling disease. Crop rotation can dramatically reduce impacts of seedling disease. Following cotton with cotton allows disease-causing populations to increase in the soil. Using high quality seed and timely planting of the crop can also reduce effects from seedling disease. Planting when soil temperatures are low favors disease formation. The last practice is the use of fungicides as seed treatment or applied in-furrow, although the former is much more economical.

In Texas, the predominant seedling disease complex of cotton includes Rhizoctonia solani, Pythium spp., Fusarium spp., and Thielaviopsis basicola. Several pathogenic and saprophytic fungi also attack cotton seed before or during germination, causing a soft, watery decay. Pythium and Fusarium are the two predominant genera involved in seed rot. These fungi can spread rapidly from seed to seed. Other saprophytic fungi associated with seed rot are Aspergillus, Rhizopus, and Penicillium.

Rhizoctonia. Rhizoctonia is commonly called Soreshin, Rhizoc and damping-off. It is the most common cause of post-emergence damping off throughout the world. In Texas the principal causal agent of post-emergence damping off is Rhizoctonia solani. It invades the cotton plant at soil level and produces a sunken lesion which girdles the hypocotyl (stem). Rhizoctonia attacks the seedling, forming dark, reddish brown, sunken lesions on the hypocotyl near soil level. The fungus often invades and girdles the stem, giving it a "wire stem" appearance. This condition is referred to as "soreshin." This condition causes the seedling to collapse. In wet conditions, the lesion can extend upwards several centimeters from soil line. Plants surviving Rhizoctonia are weakened and they bear the mark of the stem-girdling lesion at the base of the stem (Soreshin). Rhizoctonia occurs most often under conditions of excessive soil moisture, predispose cotton seedlings to infection by reducing their rate of growth. Infection occurs over a wide range of soil moisture levels. Chloroneb (Demosan®®), Triadimenol (Baytan ), thiram, captan, and PCNB (Terraclor®) are effective against Rhizoctonia but not against Pythium or Thielaviopsis.

Pythium. Pythium is commonly known as root rot, seedling rot, seed rot and pre-emergence damping off. It occurs when species of Pythium fungi infect the seed and radical. The seedling hypocotyl (stem) can also be affected at soil line, causing post-emergence damping-off. It causes a watery, straw colored decay of the roots. This fungus rots the cortical tissue, which can easily be striped off, leaving the central stele of the tap root intact. Pythium seedling disease is most severe during cool, wet conditions. At later stages of plant development, Pythium may cause stunting and chlorosis. Pythium is most damaging to cotton seedlings at low temperatures and high soil moisture content. The degree of infestation is also impacted by soil texture and organic matter, being more prevalent in clay and organic soils. In general, Pythium is more commonly the causal fungus if the soil has remained saturated for several days or is poorly drained. Metalaxyl (Apron®), etridiazole (Terrazole®®, ETMT) and mefanoxam (Apron XL , Ridomil Gold®) are effective against seedling disease caused by Pythium but are not effective against the other fungi of the seedling disease complex.

Fusarium. Fusarium seedling disease is commonly called damping off, seedling root rot and seed rot. Preemergence damping-off occurs between seed germination and prior to seedling emergence from the soil. Damage may occur as a soft rot on the expanding roots or on the

70 stem. Seedling root rot and postemergence damping-off occurs after the seedlings have emerged from the soil. Affected seedlings first turn light green and are stunted. As the disease progresses, seedlings wilt and then die. Symptoms on the affected seedlings vary according to the causal fungus involved. Fusarium fungi cause a dry, dark rot of the roots which moves up the root into the stem as the disease progresses. Seed treatments with PCNB (Terraclor®®) and metalaxyl (Ridomil ), or formulations of both (Terraclor Super X®) effectively suppress Fusarium seedling disease.

Thielaviopsis. Thielaviopsis is commonly called black root rot and is sometimes referred to as thick shank when Thielaviopsis infections produce thick, stunted hypocotyls. Black root rot results when the Thielaviopsis basicola fungus infects seedling roots and hypocotyls. Thielaviopsis fungi cause a dark brown to black dry rot of the roots, which progressively moves up the root into the stem as the disease progresses. It occurs often in western and northern locations in Texas. Thielaviopsis is more prevalent in clay soils than sandy soils and is usually most severe under cool, wet conditions. Infection occurs at the seedling stage with roots and the portion of the hypocotyl below soil line rotting and turning black. When older plants are infected by Thielaviopsis the result is collar rot. Signs of Thielaviopsis include swelling/blackening of the tissue at the base of the stem and fungus growing from infection sites. Baytan® is the only fungicide that retards seedling infections of Thielaviopsis.

Seedling disease reduction practices

Destroy crop residue. Plow cotton stalks under immediately after harvest to hasten stalk and root decomposition. This practice reduces seedling disease pathogens, nematodes, and soil insect populations by depriving them of a place to overwinter.

Rotate crops. If possible, do not plant cotton in the same field for 3 years. Rotation prevents the buildup of many disease-causing organisms in the soil.

Plant high-quality weed. Poor-quality seed usually produces low-vigor seedlings. These are more susceptible to attack by fungi that can cause seedling disease. Plant seed with a minimum of 80 percent germination. Plant the most vigorous seed early in the season when seedling disease pressure is the greatest.

Plant in warm soil. For best results, plant when the soil temperature at a 4-inch depth remains at least 65! F for 3 consecutive mornings and when warm weather is forecast for the next 7 days. The National Weather Service at Auburn reports soil temperatures along with a cotton planting advisory through many radio and television stations in Alabama.

Plant on well-prepared seedbeds and in well-drained soils. Wet soils favor the growth of many soil fungi and retard or slow the growth of cotton seedlings.

Avoid chemical or mechanical injury. Excessive rates of herbicides, fertilizers, insecticides, or fungicides applied in the drill area can injure seedlings, making them more susceptible to seedling disease. Using high rates of dinitroanaline herbicides or incorporating them too deeply can inhibit root growth and increase seedling disease.

Plant only treated seed. Seed treatment will kill most fungal pathogens on the seed coat and protect the seed during germination. Practically all seed sold by commercial seed producers are treated with a fungicide. Producers who save their own seed should treat them with a recommended fungicide. Since several fungi cause seedling disease, two or more fungicides may be needed for control.

Use soil-applied Fungicides at planting. Soil applied fungicides provide added protection in fields where there is a history of seedling disease. They are not intended to replace fungicide

71 seed treatments, but to supplement them. These fungicides can be applied as granules or as sprays and are applied in the seed furrow and covering soil during the planting operation.

Many growers prefer granular fungicides because they can be applied with granular applicators thus eliminating the need for additional spray equipment and water. Some granular fungicides also contain a systemic insecticide to control early-season insects.

Fungicides applied as sprays provide slightly better protection; because they can be distributed more evenly in the soil than granules. According to studies conducted in the Mississippi Delta, soil applied fungicide sprays provide 10 to 15 percent better protection against seedling disease.

For best results, apply fungicides in a minimum spray volume of 5 gallons per acre. Use two nozzles. Mount the front nozzle just behind the seed-drop tube to treat the soil immediately surrounding the seed. Direct the rear nozzle to treat the soil as it falls into the seed furrow.

The choice of soil applied fungicides, like fungicide seed treatments, depends upon the type and inoculum potential of seedling disease fungi present in individual fields. Since Rhizoctonia is almost always present in most Texas cotton fields. Soil applied fungicides should always contain a fungicide that is active against Rhizoctonia. A soil applied fungicide with activity against Pythium should be included if the field contains heavy, cold soils that hold excessive moisture.

Unfortunately most fungicides which are active against Rhizoctonia do not control Pythium. Likewise, fungicides with activity against Pythium do not control Rhizoctonia or other soilborne fungi. The two granular formulations of soil applied fungicides contain fungicide combinations that are active against both Rhizoctonia and Pythium. Terraclor Super X® contains PCNB, which is active against Rhizoctonia and etridiazole, which controls Pythium. Ridomil® 11G PC contains PCNB plus metalaxyl for Pythium control.

The emulsifiable formulations for sprays are more specific and contain a single active ingredient. Terraclor®® 2E controls only Rhizoctonia and Ridomil 2E controls only Pythium. Therefore, these fungicides should be used in combination in fields where both Rhizoctonia and Pythium are a problem

Root and vascular diseases

Bronze wilt

Bronze wilt is a recently recognized cotton disease sometimes called "copper top," "red wilt" and "Fourth of July disease." It was first recognized as a problem in Mississippi and Louisiana in 1995, and in Texas, Arkansas, Tennessee and North Carolina in 1996. In 1997, the disease was noted for the first time in Georgia and California. Devastating losses from bronze wilt occurred in 1998 when losses exceeding 25 million dollars occurred across the cotton belt. It was recorded on Pima cotton that year in Arizona and California, where severe boll losses occurred. In 2004, Texas experienced cool temperatures during June and early July, but temperatures exceeded 95 !F during late July and most of August. During the high temperatures experienced at this stage of cotton development bronze wilt produced excessive abortion of bolls and seed embryos.

Bronze wilt is most severe in short-season upland cotton varieties, especially when they are grown in production systems that set and mature fruit in a short-season cultural systems. Several of the varieties that are most susceptible to bronze wilt are derived from crosses involving "TAMCOT SP-37" or its progeny "MISCOT T8-27" (see Genetic links to bronze wilt).

72 Causal agent and disease development. In 1996, several commercial seed companies asked USDA and Texas A&M University plant pathologists at College Station to determine the cause of bronze wilt. This team found two species of bacteria in seed from 24 farms in the upper coastal area of Texas. Greenhouse studies confirmed that heat stress and a newly identified strain of the bacterial species, Agrobacterium tumefaciens, contributed to yield losses of between 20 and 50 percent and led to poor fiber and seed quality.

The team at College Station determined that the strain of A. tumefaciens, called biovar 1, is definitely associated with bronze wilt and is present in the seed of all U.S. cotton varieties. This was the first time scientists had isolated the newly discovered strain from both seeds and roots of affected cotton. The bacterium is also present on seeds and roots of peanuts, soybeans, and dry beans. Although this doesn't prove that the bacterium causes bronze wilt, there is a high correlation between the presence of the bacterium and disease symptoms. More research is needed to pin down the precise relationships between the organism and bronze wilt.

It has been speculated that low levels of potash (potassium) are also associated with the problem. Fields severely affected by bronze wilt in 1998 also showed some possible symptoms of potash deficiency. However, potash deficiency did not cause the disease or its symptoms. In fact, the vascular failure of plants with the disease actually led to the symptoms of potash deficiency.

Symptoms. The first visual sign is that the leaves of a single plant may wilt unexpectedly. This is followed by the development of a bronze coloration or reddish coloration. The stem will develop a deep red or almost maroon color just before the plants collapse. The bronze or red discoloration and wilting of leaves is often followed by severe shedding of bolls and other fruiting forms.

During the day, the leaves of affected plants will be very hot to the touch compared to leaves of healthy plants. The higher leaf temperature is probably caused by the limited ability of damaged feeder roots to take up water from the soil. This is due to an apparent shut down of the vascular system and a reduction in transpiration and evaporative cooling. The symptoms begin as a few scattered plants in the field and then will spread to more plants until the entire field may be effected. When the stems are cut, and the vascular tissue is examined, there will be no visual discoloration or other evidence of blockage like that associated with Verticillium Wilt. This problem may lead to, and is generally associated with, leaf and boll shed.

The diagnostic symptom of this disease is the health of the upper taproot and lower stem. If leaves show symptoms and the upper taproot and lower stem appear healthy it is most likely bronze wilt. The best way to avoid this disease is to plant non-susceptible varieties.

Symptoms most often occur during fruit development and may become progressively more severe as bolls mature. Symptoms usually go through a series of predictable stages. In most cases, the tops of diseased plants first become chlorotic. Then leaves turn bronze or red and may begin to droop and wilt. The bronze or red leaves on diseased plants are warmer to the touch than the green leaves on plants without symptoms. The first symptoms may be transient and disappear. If the disease progresses, the upper leaf and stem tissue may turn red and many squares and bolls may shed abnormally. However, after fruit shed, leaf color can revert to green or reddish green. If the disease is particularly severe, all the foliage may rapidly wilt and collapse within a few days of the first symptoms. Then leaf and stem tissue of the upper canopy may turn dark and necrotic.

The phloem and bark tissues of petioles, peduncles and stems sometimes collapse and become discolored in plants affected by bronze wilt. Boll peduncles, leaves subtending bolls, fruiting branches, and the main stem near fruiting branches are most often affected.

73 The darkened lesions vary from a few millimeters to many centimeters in length. As the bolls mature, the entire terminal end of a branch or stem may become black and all leaves die or abscise. Young bolls often abscise or fail to develop, showing blackening or splitting of the carpel sutures before they are mature. Bracts may die prematurely, and leaves subtending the boll and the fruiting branch may develop necrotic margins and drop off.

In most cotton-growing areas the root systems of diseased plants are stunted, with few if any secondary roots in addition to the taproot. Both the wood and bark of the taproot appear healthy except for small dark scars or pustules left from the death of secondary roots.

The symptoms of bronze wilt are difficult to differentiate from other disease symptoms, nutrient deficiencies and pathological conditions resulting from environmental stress. In fields where boll shed is severe, cotton may regrow as a result of the reduced boll load. This often leads to rank growth that attracts insect pests to affected fields.

Distinguishing bronze wilt from other diseases. The above-ground symptoms of bronze wilt may resemble those of Fusarium and Verticillium wilts; Macrophomina and Phymatotrichum root rots; damage from root knot, reniform, stunt or lance nematodes; potassium, sulfur and phosphorus deficiencies; drought; and extended periods of high temperatures. Bronze wilt can be distinguished from other disease by the condition of the lower stem and upper taproot and the spatial pattern of diseased plants in the field.

The pith, wood and bark of the lower stem and upper taproot remain light colored and appear healthy with bronze wilt. In contrast, yellow or brown streaks develop in and around xylem vessels in the wood of plants with Fusarium or Verticillium wilt. Fungal root rots cause discoloration and rotting, first of the bark and then of the entire root. Rhizoctonia causes girdling of the stem at the soil line and black discoloration of the pith in both the stem and the taproot. If the upper taproot and lower stem appear healthy, leaf symptoms are caused by bronze wilt. Bronze wilt often appears first and most severely on plants at the ends of rows or along the sides of fields, or in single, isolated plants.

Bronze wilt often causes more distinct symptoms in low- than in high-density stands. Symptomatic plants within rows occur randomly. The opposite of this pattern is seen with nutrient deficiencies, drought and nematode damage; these problems occur in sizable areas or clusters in the field where similar damage occurs to all plants.

Genetic predisposition to bronze wilt – "B genes". Research by at Texas A&M has also revealed important genetic reasons why some plants are more susceptible than others to bronze wilt. In several areas of the Cotton Belt, popular cotton varieties are bred with specific genes that convey bacterial blight resistance and early fruiting. Bacterial blight resistance genes used in traditional breeding programs are generally referred to as "B genes." Three genesùB2, B3, and B7ùare in the genetic background of Tamcot SP37, a Texas cotton variety that has been used in many breeding programs worldwide. This variety provides the desired early fruiting, which permits farmers to save on insecticides.

Breeders who used TAMCOT SP37 as a parent for earliness could have inadvertently separated the B genes from each other. Greenhouse studies showed that varieties with B7 alone are very susceptible to bronze wilt and develop high Agrobacterium tumifaciens biovar 1 populations in roots.

At present, there is reason to believe that bronze wilt is primarily associated with varieties that have TAMCOT-SP37 in their breeding background. In 1995, it was seen in the 1200 series Hartz cottons and Stoneville 132. In 1998, it was found in the Paymaster 1200 series (1220-1215) and Stoneville 373. The Paymaster varieties were acquired form Hartz.

74 Prevention and control. At present, there is no cure for bronze wilt. Once a field shows symptoms of bronze wilt, the disease will run its course. There is no treatment of soil, seeds or plants that will mitigate or prevent the disease. Variety selection and stress reduction during the hotter months of summer are the best means of prevention.

Avoid Susceptible Varieties. Planting varieties that have no known history of bronze wilt is the easiest way to reduce losses from this disease. Many varieties susceptible to bronze wilt have been removed from the market. Most seed companies now include information about bronze wilt susceptibility in their product guides.

Cultural Practices. If any of the varieties known to show the symptoms are planted, they must never be allowed to stress. It appears that the incidence of this problem is worse when the plants have a boll load and are put under a hot-dry stress or just heat stress. Low levels of potash in the soil may also influence this the incidence and progress of the disease.

If susceptible varieties are planted, the following cultural practices may make the disease less severe:

! Plant as early as possible to avoid high soil temperatures during fruiting.

! Use no more nitrogen fertilizer than is appropriate to achieve desired yields.

! When soil tests indicate deficiencies, fertilize with phosphorus, potassium and sulfur before planting.

! Prevent water stress by irrigating sufficiently. Susceptible cultivars can still suffer considerable losses in spite of good cultural practices if climatic conditions favor the disease.

Cotton root rot

Cotton root rot, sometimes called "Texas root rot," is caused by Phymatotrichum omnivorum. It is a fungus that resides in certain warm, alkaline soils. It occurs readily in certain areas of the heavier soils throughout south, central and western Texas. Infected plants wilt and die suddenly without shedding leaves. Symptoms are seldom evident until mid-season during boll development. Losses are high because entire plants are killed quickly. Dead plants will remain standing in the field but can be easily pulled from the soil.

Causal agent and disease development. Cotton root rot has the largest host range of any known plant pathogen. It kills cotton and at least 2,300 other species of unrelated dicotyledonous (broadleaf) plants. Monocots (grasses, sedges, rushes, and lilies) are immune. The fungus attacks only mature or maturing plants. Seedlings are not susceptible. It is not only an important disease of cotton, but also of alfalfa, grapes, fruit trees, and many ornamental plants including conifers. Although thoroughly studied since its discovery in 1888, researchers and farmers still have little ammunition in the fight against the disease.

It also has two surefire survival techniques. The fungus produces hyphal strands that colonize and penetrate living roots of host plants, causing the entire root system to rot. A dense web of hyphae (fungal fibers) covers the root once the fungus has penetrated and caused decay. The strands grow through the soil and infect the healthy roots of nearby plants. The fungus also survives for long periods of time in the soil as small, dark resting bodies called sclerotia, which are produced by the hyphae. Sclerotia remain inactive until favorable soil conditions cause them to germinate. This usually involves the presence of an appropriate host plant. At that time, a hyphal strand will grow from a sclerotium and invade the susceptible host plant root system and start the life cycle all over again.

75 Cotton root rot sclerotia are extremely hardy and long-lived. Sclerotia have been found as deep as 12 ft in the soil. They can survive as long as 20 years. They are resistant to extremely adverse physical conditions and to chemicals that ordinarily kill the fungal hyphae. When these features are combined with the enormous host range of the cotton root rot pathogen, they make management a nightmare for unfortunate growers faced with the disease.

The fungus can also survive on roots of native vegetation, such as mesquite, without causing any disease. Second, the fungus persists almost indefinitely in soil. Much of the fungus is found in the top 2 to 6 feet of soil, however sclerotia (fungal survival structures) have been found over 12 feet deep. Another concern is that isolates of the fungus are non-specific. For example, an isolate infecting cotton is also virulent on fruit trees and ornamentals and vice versa. Thus, housing developments in old cotton and alfalfa fields with a history of the disease can be disastrous for urban landscapers.

The fungus is only active in summer months when air and soil temperatures are high. The greatest incidence of disease occurs when soil temperature at 1 foot deep is greater than 80°F and the air temperature in the plant canopy is above 104°F. When environmental conditions are favorable for fungal activity, the pathogen invades plants through their root systems. Infected roots rot and cannot transport water to the above-ground portion of the plant.

A single feature of the cotton root rot fungus that favors the cotton farmer is that it is found only in small pockets of infected fields. It is not widespread and does not spread rapidly in the soil from its point of origin. It has no means of air-borne spread. However, P. omnivorum may produce large spore mats at the soil surface during periods of high moisture, such as rain or irrigation. The spores in these mats are not viable. They have never been successfully germinated and do not spread the disease from one location to another. They apparently have no function in the survival, spread or infection process of the pathogen.

The only known spread of the cotton root rot pathogen is between infected plants and healthy plants. In these cases, it spreads slowly from plant to plant when fungal strands from infected roots or germinating sclerotia grow through the soil from infected plants to the healthy roots of nearby host plants.

Fortunately cotton root rot is limited in geographic distribution and does not readily spread from one location to another. The fungus is restricted geographically to the southwestern United States and northern Mexico in alkaline soils with low organic matter. It also occurs only at elevations below 5,000 feet and is typically found in relatively small areas in fields. It is particularly prevalent in heavier clay or silty loam alluvial soils in valleys, river flood plains and agricultural areas along the Rio Grande and Pecos rivers.

Cotton Root Rot occurs throughout the southwestern United States and Mexico. It is easily recognized in infested cotton fields in late summer by large areas of dead plants, hence its common name. It is most common in the low desert areas where winters are mild, but also occurs at higher elevations, up to at least 5000 ft, where susceptible plants are introduced. Disease occurs in different soil types and in areas as diverse as the low lying flood plains of rivers and washes of central and western Arizona and the higher grassland hills of southern Arizona. The pathogen, Phymatotrichum omnivorum, is an indigenous soil borne fungus that is found deep in soils.

Symptoms. Above-ground symptoms, which occur around mid-season, include a sudden wilting of foliage followed by rapid death of entire plant within a few days. Leaves shrivel, turn brown and die, but they remain attached to the plant. Often a white mat of fungal growth is visible around the base of the plant. A red to burgundy lesion is visible below the bark on

76 the lower stem near the soil line. The roots may be covered with brown thread-like strands of the fungus.

Symptoms on above-ground plant parts resemble water stress. The first evidence of disease is slight yellowing of the leaves. Leaves quickly turn to a bronze color and begin to wilt. Permanent wilting of the branches can occur very rapidly, as little as two weeks from the first expression of disease. The tree dies with leaves remaining firmly attached . In some cases, the tree wilts so quickly that the leaves hardly change color, though they will become dry and brittle. A reddish lesion around the crown of the plant may develop on trees and shrubs killed by the fungus, which is a good indication that a location is infected with the disease.

Evidence of P. omnivorum can also be found on or near infected host plants, particularly trees and shrubs. The pathogen produces fungal strands on the surface of infected roots. These strands look like threads and are visible with a good hand lens. When strands are observed under a compound microscope, cruciform (cross-shaped) hyphae unique to this fungus can be seen. Another sign is the formation of a white- to tan-colored spore mat on the surface of the soil around infected plants. Although the spore mats do not spread disease, they are clear evidence of its presence.

Prevention and control. Research to control this disease has been extensive during more than 80 years. This has revealed a great deal about the biology, ecology and epidemiology of the disease. However, in spite of a vast base of knowledge about cotton root rot, there are no good control methods. There is no resistance or tolerance to this disease in most of the commonly infected hosts.

The best recommendation is to avoid land known to be infested with the cotton root rot fungus. Unfortunately, there is no way to test soils for presence of the fungus other than planting a susceptible plant. Since other pathogens can cause root rots and other factors could result in similar symptoms, it is very important that a positive identification of the pathogen be made by an experienced plant pathologist. Hyphae and strands of the fungus used for diagnosis are easiest to find on fresh tissue but can also be found on older, decayed roots. If mesquite land is to be cleared for planting, it may be worth the time and money to preplant the area in cotton or alfalfa. Plants with a tap root like these are infected and show symptoms in one season, while trees and shrubs may not show disease for some time after planting. If no symptoms develop on test crops, growers can be relatively sure the land is safe for cotton.

Tolerant and immune plants. Although many dicotyledons have been found to be susceptible to some degree, some are very tolerant. Mesquites, palo verde, Atriplex, hackberry, jojoba, and cacti are tolerant and remain healthy in landscapes where other plants have died from disease. All monocots, such as palms, yuccas, grasses, sedges, lilies and rushes are immune and are good choices to plant anywhere that cotton root rot has been diagnosed.

Cultural control. Cultural practices such as deep moldboard plowing and crop rotation have had limited success. The overwintering sclerotia can remain viable in a field for more than 20 years. In areas known to be infested with P. omnivorum, the only sure control is to plant non-hosts. Unfortunately, the extensive host range of the pathogen limits choices. Monocots, such as corn, small grains, and all grasses are immune. Dicots grown as annuals often escape the disease. Additionally, most native desert plants are apparently tolerant to the disease.

There are some cultural practices that can be used to alter the soil environment so it no longer favors P. omnivorum. These practices may help reduce the effect of the pathogen if they are followed every year. The procedure alters the growing environment in the root zone of susceptible plants by applying soil amendments to increase organic matter and reduce soil pH. These practices must be followed annually or the soil environment will quickly return

77 to its typical state (high pH and low organic matter), which again favors the fungus. The procedure is better adapted to small-scale, high-value horticultural crops than to cotton. However, continued research may provide an economic way to apply it to cotton.

The soil modification procedure consists of loosening the soil in a broad and comparatively shallow basin just beyond the drip line around susceptible plants in areas known to harbor cotton root rot. The area is then covered to a depth of 2 inches with manure or compost. Ammonium sulfate and sulfur are then layered on top of the organic matter at a rate of 1 lb per 10 sq ft. The basin is then immediately flooded with enough water to wet the soil to a depth of 3 feet. This high level of soil moisture must be maintained for several weeks. If plants are treated before permanent wilting, they may recover. This procedure must be applied every year in March or April to Known root rot infested areas of fields.

Some success reducing the effect of the disease has been achieved by growing and incorporating a green manure cover crop in affected fields. This helps to stimulate vigorous rooting of plants, enabling them to better withstand disease pressure. Additionally, the incorporation of the green manure crop into the soil may help to stimulate soil microflora, which compete with P. omnivorum.

Chemical control. Chemical control methods have been investigated for more than 80 years, but none have been found to be effective. Soil fumigation is equally ineffective in controlling cotton root rot. Early planting with early maturing varieties may help prevent the disease. There are no resistant varieties. Emerging genomic research promises to reveal the interaction between the pathogen and its host plants, and this may prove to be a key to developing genetically modified cotton varieties resistant to this disease.

The ability of the fungus to survive deep in soil has eliminated the possibility of using fungicides and fumigants to control the disease because these materials can only penetrate a limited distance into the soil. Fumigating infested planting holes in areas where trees have died will usually only delay the onset of disease in newly planted trees. When a replanted tree's roots reach deep enough in the soil, they will contact the surviving fungus and succumb to the disease.

Finally, chemical barriers have been used to prevent the spread of disease from one infected plant to another. Applying sulfur in trenches 4 to 6 inches wide and 4 to 6 feet deep around the outside of the drip line of infected plants has prevented the spread of P. omnivorum for more 7 years. However, it does not protect plants within the infected area.

Vascular wilt diseases (Fusarium and Verticillium)

Fusarium and Verticillium fungi produce a vascular wilt that results in a discoloration in the stems of cotton plants. These wilt diseases prevent the proper translocation of water and nutrients, and cause infected plants to wilt and die. Verticillium is more of a problem in West Texas with Fusarium a problem in East Texas. Disease development for both diseases is favorable under cool wet conditions.

Fusarium wilt

Fusarium wilt is caused by the fungus Fusarium oxysporum f. sp. vasinfectum. Fusarium wilt is more prevalent in the lighter-textured acid soils of Texas. Unlike Verticillium wilt, seeds from diseased plants can become infected and serve to spread the fungus. The fungus may attack cotton seedlings, but the disease usually appears when the plants are more mature.

Soils in which Fusarium wilt occurs also favor root knot nematodes and the two are often found together. Reniform nematodes (which occur mostly in the lower Rio Grande Valley)

78 also predispose the plant to attack by the fungus. Control of nematodes is of major importance in reducing Fusarium wilt.

Causal agent and disease development. Fusarium wilt usually occurs when the Fusarium fungi penetrate through root injury caused by nematodes. Infected areas are irregular in shape and size. Water-conducting stem tissues turn brown and become inactive, resulting in wilted foliage. Leaves turn yellow between veins and eventually shed as plants die to leave bare stems. Diagnosis is confirmed by splitting the stem to reveal dark brown, vascular discoloration and streaking characteristic of wilt. Symptoms usually appear first on oldest leaves at bloom. Areas of leaf margin wilt then turn yellow. The entire leaf eventually may wilt and turn yellow. Leaves defoliate prematurely. In cross-section, a brown layer of tissue appears just below the bark of the lower stem. Bolls may open prematurely. These symptoms are difficult to distinguish from Verticillium wilt.

Symptoms. Affected plants are first darker green and stunted, followed by yellowing of the leaves and loss of foliage. First, symptoms appear on lower leaves around the time of first flower. The leaf margins wilt, turn yellow, then brown, moving inward. Infected plants fruit earlier than normal with smaller bolls that open prematurely. A diagonal cut across the stem will reveal vascular discoloration just beneath the bark extending down the tap root. Wilting occurs rapidly following a rain preceded by a dry spell. Severely affected plants shed all their leaves and most of their young bolls. This distinguishes this disease from cotton root rot. Fusarium wilt is difficult to distinguish from Verticillium wilt and is best diagnosed through expert laboratory isolation of the specific fungus.

Prevention and control. Cultural practices effective for reducing Fusarium wilt losses include avoiding seed from infested fields in humid climates, rotation with non-susceptible crops. Newer cotton varieties often have improved levels of resistance to root-knot nematode, Fusarium wilt and Verticillium wilt. However, nematicides and soil fumigants are the only other method of suppressing Fusarium wilt. Chemical control with row banded nematicides can reduce the level in nematode caused Fusarium wilt.

Verticillium wilt.

Verticillium wilt is caused by the fungus Verticillium albo-atrum. Like Fusarium wilt, Verticillium fungi produce a vascular wilt that results in a discoloration in the stems of cotton plants and often produces their eventual death. Verticillium is more of a problem in West Texas than in the rainier, more humid parts of the state. Like Fusarium wilt, Verticillium wilt disease development is more favorable under cool wet conditions.

Causal agent and disease development. The Verticillium wilt pathogen survives in the soil as small, dark resting bodies called sclerotia. The sclerotia can withstand adverse environmental conditions. Susceptible plants growing in Verticillium infested soil may not be severely attacked if environmental conditions are not suitable for fungal growth. The disease is more prevalent during periods of cool, wet weather. The fungus is not transmitted in seed, but can be introduced in the field by infested gin trash and burrs. The disease is more common on heavier soils than on light sandy soils.

Symptoms. Young plants infected with Verticillium wilt show yellow leaves and stunting, and often die. Following the seedling stage, older plants exhibit a chlorotic mottling on the leaf margins and between the major veins. Plants attacked during later stages of growth display a mottling on the lower leaves first, later progressing toward the top of the plant as the season progresses. Often a single branch shows symptoms in the early stages of disease. Yellow progresses inward, followed by brown, and the leaf finally dies. Severely affected plants shed all their leaves and most of their young bolls. This distinguishes this disease from cotton root rot. Plants infected by Verticillium may survive throughout the growing season and send out young sprouts or shoots from the base of the plant. A diagonal cut

79 across the stem will reveal vascular discoloration just beneath the bark extending down the tap root. Verticillium wilt is difficult to distinguish from Fusarium wilt and is best diagnosed through expert laboratory isolation of the specific fungus.

Leaf symptoms of Verticillium wilt are similar to those produced by Fusarium, and the internal tissues of the stems are discolored in both diseases. The only reliable way to distinguish the wilts is through a laboratory isolation of the fungus.

Prevention and control. Control measures include avoiding excess nitrogen, crop rotation, shallow cultivation to avoid root pruning, avoiding excess irrigation, and planting resistant varieties. Soil fumigants provide only partial control of Verticillium wilt. Their use is seldom justified economically.

Foliar and fruit diseases

Ascochyta (wet weather) blight

Ascochyta or "wet weather blight is caused by the fungus Ascochyta gossypii. The disease is prevalent in most cotton producing areas of the Texas, but occurs more often in areas of higher rainfall. Both seedlings and older plants are susceptible, but younger cotton is more seriously injured. An entire stand may be lost as a result of the fungus attacking the hypocotyl and killing the plant. Serious outbreaks of the disease may follow extended rainy periods with serious defoliation occurring. The damage is generally spotty and many plants recover when dry, warmer weather returns. The disease occurs on the leaves, stems and branches.

Symptoms. First, small, round, reddish-brown spots with a dark brown border appear on the leaves. Later, the center of the lesions become ashy in color and may fall out. The lesions often occur at the base of the petiole. Defoliation may result from large lesions that coalesce. On stalks and branches, the lesions are dark brown, elongated and slightly sunken cankers. Under conditions favorable for the disease, the lesions may completely encircle the stem or branch and kill the plant above the lesions.

Prevention and control. The fungus may be seed-borne but survives primarily in the soil on infected plant residue. Crop rotation is the best way to avoid disease. Avoid planting in fields with a history of the disease, particularly in a year following disease outbreaks. Use of acid delinted seed and suitable seed treatment fungicides will minimize carry-over. Destruction and plowing under of plant residues will also aid in reduction of the disease.

Bacterial blight

Bacterial blight of cotton, also called angular leaf spot, vein blight, black arm, black leg, and boll rot, depending on the portion of the plant infected, is an important and potentially destructive bacterial disease. It is caused by the bacterium, Xanthomonas campestris pv. malvacearum. This organism affects all above ground parts of the cotton plant during any stage of its growth.

Texas farmers have faced this disease before in the 1960s and the 70s. Cotton yield losses in excess of 10% have been reported in the past. Historically, most cases of bacterial blight have been reported as being spread by fall rains. However, any water drops can carry the bacterium. Bacterial blight spreads when water drops carrying the bacteria splash onto plants. It is at its worst during rain or watering from sprinkler irrigation. Drops from sprinkler systems or rain deposit bacteria onto the leaves of cotton plants. If droplets are heavy and cause splashes, the bacteria spreads to all the leaves and developing bolls. In diseased plants, most of the bolls are also diseased. The lint from diseased bolls is discolored and of poor quality. Gins cannot process the lint.

80 Whether bacterial blight comes from rain or sprinkler irrigation, it can cause disastrous losses at the end of the season when cool weather often prevents plants from drying quickly. When wet weather comes before the harvest, it attacks cotton until there is no value from the harvest. In short-season, dryland production systems greater losses may occur. Although significant losses to this disease in the United States have not been reported in many years, farmers in the Texas High Plains have recently become concerned with the incidence of bacterial blight in that production region. The Plains Cotton Growers Association has recently contributed to research on this disease.

Symptoms. Bacterial blight starts out as angular spots, which first appear on the leaves as water-soaked areas with a red to brown border. The angular appearance is due to restriction of the lesion by fine veins of the cotton leaf. Spots on infected leaves may spread along the major leaf veins. Occasionally, a black, water-soaked area occurs along a large vein in a leaf. As the disease progresses, leaf petioles and stems become infected, turn dark brown or black, and drop leaves prematurely. This condition is sometimes called "cotton black leg." Black cankers may girdle the stem or branches causing the portions to die above the canker. A white waxy crust containing the bacterium may form on old leaf spots or cankers. Often the surrounding tissue becomes yellow, giving a halo effect. Infected leaves drop from seedlings and from older plants.

Bolls may become infected. Spots on bolls appear as round, water-soaked areas, but later turn dark brown or black. Spotted bolls may fail to open and lint may be discolored with a yellow stain. The disease may progress to a condition known as "boll rot," which produces rotted seed and severely discolored, poor quality lint. Before boll rot is evident, dark, irregularly shaped spots can be found on bracts surrounding the lower portion of the boll. Black spots or cankers may occur on the stems or branches (black arm) causing girdling and death of some branches. Infected bolls may fail to open.

Bacterial blight resistance. Texas A&M Plant Pathologists at the Lubbock Experiment Station are investigating sources of resistance to bacterial blight. In an 18-acre nursery , 79 different cotton varieties were infected with bacterial blight. After inoculating plants several times, the researchers rated different varieties according to susceptibility and resistance. It was clear what was susceptible and what was resistant. At least 31 varieties were highly resistant to completely immune. When resistance research is complete, Texas Cooperative Extension will publish which cotton varieties show the most resistance to bacterial blight.

Prevention and control. No specific control of bacterial blight has yet been found. Remedial actions to arrest disease development are not available. Control measures depend largely on eliminating sources of infection and growing resistant or tolerant varieties.

Cultural control. Since the bacterium overwinters in crop residue, crop rotation and crop residue destruction will reduce inoculum in the field. Fields that have bacterial blight should be rotated to a different crop the following year if a blight-resistant variety is not available. In fields with bacterial blight, crop residues should be shredded and plowed under as soon as possible. Acid delinting of cottonseed has eliminated carry-over. Keeping the canopy as open as possible to reduce humidity and promote drying of the foliage may prove beneficial in limiting the progress of this disease. Do not cultivate or move equipment through fields when foliage is wet.

Infested fields should be harvested as soon as possible. The cotton variety, seed lot and a rating as to disease severity should be determined. Many varieties have exhibit resistance to bacterial blight. However, varieties adapted to particular growing regions must be identified for economic production and blight resistance in that region. Producers should consult current Extension and Experiment Station publications for blight resistant varieties.

81 Chemical control. There are no pesticides registered specifically for control of bacterial blight. However, growers can take positive action by applying mid-season plant growth regulators (PGRs) to keep internodes short and prevent rank growth that favors the start and spread of bacterial blight infections.

Boll rot

Cotton boll rot is common in very heavy cotton growth. If excessive stalk growth has occurred, one may encounter boll rot problems. Reducing some of the leaf tissue with the selective use of defoliants may be a practical answer. Good weed and insect management will decrease incidence of boll rot (see bacterial blight).

Cotton leaf rust

Cotton leaf rust or southwestern rust is caused by the fungus organism Puccinia cacabata. It commonly occurs in the Trans Pecos region of Texas. The fungus is common throughout the Desert Southwest and also occurs in New Mexico, Arizona and California. It infects all varieties of both upland cotton (Gossypium hirsutum) and Pima (G. barbadense). No cotton varieties are known to be resistant to the disease. Pima cotton is more susceptible to defoliation by leaf rust than upland cotton. Two or three pustules per leaf can cause Pima leaves to drop. Although upland cotton can tolerate more leaf infections, leaves discolor and often drop when as few as 5 to 10 pustules are present.

After mild and comparatively wet winters, 1991 and 1992 experienced very severe outbreaks of cotton leaf rust. It will be particularly bad in Reeves County. The host grasses showed many rust lesions. An abundance of spores in June, July, and August produced prolonged outbreaks in mid-season that lasted in some locations until the end of the season. In 1991, the Pima crop in the Pecos and El Paso valleys experienced losses as great as 75%. Upland cotton also was severely affected, and yield losses in affected fields were estimated at more than 50%.Outbreaks of the disease are erratic because the teliospores are so dependent on free moisture for spore germination.

Causal agent and disease development. Puccinia cacabata has a complex life cycle that begins on several species of grama grass. In West Texas, black grama (Bouteloua eriopoda) is its primary host. Cotton leaf rust requires two hosts to complete its life cycle and is said to be "heteroecious." Heteroecious rusts spend part of their life stages obligatorily on one host and the remainder of their life stages on another. They alternate between the two host species.

The cotton leaf rust disease cycle begins with windblown teliospores from telia (fruiting bodies) on black grama grass. A rainfall of an inch or more, followed by 12 to 18 hours of high humidity, is needed in June or early July for disease development. Under these conditions, the teliospores germinate and the fungus invades leaf, stem, petiole and fruiting tissues of cotton plants. Rust first appears as small, yellowish spots or pustules on leaves, bracts, green bolls, and stems. These enlarge, developing orange to reddish centers. Later, large orange pustules called aecia appear on the lower leaf surface. These are the fruiting bodies that discharge orange aeciospores, which infect the green tissues of black grama grass. The fungi invade the grass tissues and produce black lesions called telia in which the disease passes the winter. It is from the telia that spores are released that start the disease cycle the following year.

Symptoms. The first symptoms observable on an infected cotton plant are bright yellow to orange spots on the leaves, bracts and bolls that appear during mid-summer shortly after a rain. Within a week following infection, yellowish spots occur on leaves, bracts, green bolls, or stems. These enlarge, develop orange to reddish centers, and soon form an orange- yellow mass, usually on the under surface of the leaf.

82 When the orange pustules on cotton leaves are comparatively few in number, they do little damage to cotton. Damage to cotton results from the shedding of leaves. The rust lesions also weaken stalks, stems and petioles, causing breakage on these parts. Broken stalks are more difficult to cultivate and harvest mechanically. In years of severe rust development, the yield of lint may be reduced by more than 50 percent, particularly where infection is heavy and damage occurs to developing bolls.

Prevention and control. No cotton varieties are known to be resistant to the disease, although a degree of tolerance has been found in some breeding lines. Pima cotton is more susceptible to defoliation by leaf rust than upland cotton. Two or three pustules per leaf can cause Pima leaves to drop. Although upland cotton can tolerate more leaf infections, leaves discolor and often drop when as few as 5 to 10 pustules are present.

Chemical control. The only effective means to control of cotton leaf rust outbreaks are applications of a mancozeb (Dithane M-45®®, Manzate )foliar fungicide before the cotton is infected. This is the only labeled fungicide, but it can not control the fungus after infection has occurred. Applications must be made before or immediately after rains during the period of high risk from windblown spores from grama grass hosts. An important aspect of a cotton leaf rust control strategy is that of applying mancozeb as preventive treatment. During years of high rust pressure, it is important to treat plants before free moisture from rain causes rust spores to germinate. Compatibility with insecticides is not a problem because mancozeb is compatible with most pesticides used to control insect and mite pests of cotton. Without the use of mancozeb, disastrous losses from cotton leaf rust outbreaks will be unpreventable.

Other foliar diseases and minor leaf spots

Other foliar diseases and minor leaf spots include those caused by the following fungi: Alternaria spp., Cercospora spp., Rhizoctonia spp., Stemphyllium spp. Two or more leaf spot disease organisms may infect leaves at the same time. Symptoms are varied, but generally these organisms cause circular concentric "target spot" type lesions. These foliar diseases tend to be more prevalent at crop maturity and during periods of high rainfall and humidity. Preventive control measures are most effective and include seed treatment, good management practices, and destruction of plant residue after harvest. Some varieties are more susceptible to late season leaf spot fungi. Some fungicides registered in cotton include these disease agents on other crops. No fungicides registered for cotton include leaf spot diseases in their cotton recommendations.

83 Fungicides

Azoxystrobin (Protégé®®, Quadris ) Azoxystrobin (Protégé®®, Quadris ) strobilurin (methoxyacrylate) fungicide is a broad spectrum, preventative fungicide with systemic and curative properties. It has activity against several important cotton pathogens, such as Rhizoctonia and Pythium. In cotton, it is used primarily in the treatment of delinted seeds. It is active against Rhizoctonia solani and provides excellent protection against this pathogen when used as a seed protectant. It also provides excellent protection against Pythium spp. Formulations for seed treatment are available primarily to commercial seed treatment establishments. Azoxystrobin has been designated a "Reduced Risk" pesticide by the Environmental Protection Agency (EPA).

Bacillus subtilis (Kodiak®®, Kodiak HB ) Bacillus subtilis (Kodiak®®, Kodiak HB ) biofungicide is a strain of the bacterium Bacillus subtilis. This bacterium colonizes the root system of the developing cotton seedling without damaging the seedling plant. It protects the seedling by taking up space that might otherwise be occupied by pathogenic organisms. This reduces the likelihood of invasion by Rhizoctonia and other pathogens. Formulations with other fungicides often combine it with PCNB and It is often used with Terraclor®® provides additional Rhizoctonia protection, while Apron is for Pythium control. This product should be combined with another fungicide for broader spectrum disease control. It is available in formulations for both seed treatment facilities and as a planter box treatment.

Captan (Captan®®, Orthocide ) Captan (Captan®®, Orthocide ) phthalate fungicide is a broad spectrum contact fungicide used to control many fungal and bacterial disease agents on many crops. It has been in use since the early 1950s. In cotton, it is used primarily in the treatment of delinted seeds. It is active against general damping-off pathogens for which it provides fair control. Captan has a low acute toxicity and generally carries the signal word CAUTION. Captan is available in formulations for use in seed treatment facilities and as a planter box treatment. Captan is very effective against a broad range of soil fungi, but its effectiveness against Pythium is only fair.

Carboxin (Vitavax®) Carboxin (Vitavax®) is a systemic anilide fungicide used as a seed treatment for control of a variety of seed and seedling pathogens. It is very often used in combination with other fungicides such as thiram or captan. Its systemic action provides it with both preventive and curative properties. Carboxin is a slightly toxic compound and carries the signal word CAUTION on the label.

Chloroneb (Nu-Flow D®®, Demosan ) Chloroneb (Nu-Flow D®®, Demosan ) organochlorine fungicide is used as a seed treatment to control a narrow range of seed and seedling pathogens. In cotton, it is used primarily in the treatment of delinted seeds. It is available for seed treatment at seed processing and packaging plants and also as a planter box treatment. Chloroneb controls Rhizoctonia but provides little if any control of Pythium spp.

Etridiazole (Ethazol®®, Terrazole ETMT) Etridiazole (Ethazol®®, Terrazole ) thiadiazole fungicide provides good control of Pythium but only fair control of Rhizoctonia. In cotton, it is used primarily in the treatment of delinted seeds. Formulations often include thiophanate methyl (Topsin®) to increase spectrum of seedling diseases controlled. It does not control Fusarium or Thielaviopsis seedling diseases.

84 Fludioxonil (Maxim®) Fludioxonil (Maxim®) phenylpyrrole fungicide is a broad spectrum seed treatment fungicide used for many crops. In cotton, fludioxonil is used primarily as a commercial seed treatment. Its unique mode of action inhibits protein kinase, an enzyme vital to the survival of many major disease pathogens, therefore inhibiting their growth and development. Fludioxonil effectively prevents Rhizoctonia infection by hindering hyphae growth from sclerotia. Like captan, it is effective against a broad range of soil fungi, but its effectiveness against Pythium is fair to poor.

Iprodione (Rovral®) Iprodione (Rovral®) dicarboximide contact fungicide is used to control a wide variety of crop diseases. Iprodione inhibits the germination of spores and the growth of the fungal mat (mycelium). The compound is used in formulations with numerous other fungicides such as thiabendazole and carbendazim. It is compatible with most other pesticides. In cotton it provides only fair control of Rhizoctonia and is seldom used.

Mancozeb (Dithane M-45®®, Manzate D ) Mancozeb (Dithane M-45®®, Manzate D )ethylene bisdithiocarbamate (EBDC) fungicide is a broad spectrum contact fungicide. It provides fair to good control of damping off pathogens. It is the only registered material that will prevent cotton leaf rust. Formulations for cotton include materials for treatment of commercial cottonseed, planter box treatment, and flowable and wettable powder formulations for foliar treatment. Although infrequently used, it is indispensable for cotton leaf rust control during years when this pathogen can destroy crops in entire regions of Texas.

Mefanoxam (Apron XL®®, Ridomil Gold ) Mefanoxam (Apron XL®®, Ridomil Gold ) acetanilide fungicide is a narrow-spectrum, locally systemic fungicide employing a more active isomer of metalaxyl. Apron XL® and Ridomil Gold are new products containing mefanoxam and are used at about half the rate of Apron®, Ridomil®® or Allegiance . It is still good practice to include this fungicide on cotton seed treatments in combination with a broad-spectrum fungicide like captan or fludioxonil (Maxim®).

Metalaxyl (Apron®®, Ridomil , Allegiance®) Metalaxyl (Apron®®, Ridomil , Allegiance®) acetanilide fungicide is a narrow-spectrum, locally systemic fungicide with excellent activity against Pythium. In recent years, it has become standard practice to include this fungicide on cotton in combination with a broad-spectrum fungicide like captan or fludioxonil (Maxim®). The active ingredient in Allegiance® is also metalaxyl and is marketed by Gustafson.

Myclobutanil (Nu-Flow M®) Myclobutanil (Nu-Flow M®) triazole fungicide is a narrow spectrum, locally systemic sterol inhibitor that blocks sterol production at the same site than as imidazoles. Ergosterol is the major sterol in most fungi. It is essential for membrane structure and function. Cell health in several important fungal groups depends on sterol mediated reactions that maintain cell membrane integrity. Inhibition of sterol effectively stops development in susceptible fungi. This attribute gives myclobutanil both preventive and limited curative properties. In cotton, it is applied primarily as a seed treatment fungicide for control of Rhizoctonia. It is often mixed with other fungicides to provide control of other fungi that it will not control. A common mixture is with triadimenol (Baytan®) for additional control of Thielaviopsis black rot.

Pentachloronitrolbenzene (Terrachlor®, PCNB) Pentachloronitrolbenzene (Terrachlor®, PCNB) organochlorine fungicide is a comparatively broad spectrum contact fungicide effective against a variety of saprophytic soil fungi and that produce seed rots damping-off. It has multiple target sites and inactivates amino acids, proteins and enzymes by combining with amino and thiol groups. PCNB (Terrachlor®) gives

85 fair to good control of Rhizoctonia but is not effective against Pythium. It may be combined with metalaxyl (Apron®®), etridiazole (Terrazole ), or azoxystrobin (Protégé®, Quadris®) to provide protection against Pythium and with triadimenol (Baytan®) for control of Thielaviopsis.

TCMTB (Argent®®, Ascend , Nusan®, Nu-Flow T®) TCMTB (Argent®®, Nusan ,Nu-Flow T®) benzothiazole fungicide is a broad spectrum bactericide and fungicide. In cotton is registered for commercial seed and soil treatment for prevention of various diseases. In cotton seed treatment, formulations are available for both acid and machine delinted seed. I provides good control of general damping-off organisms, including Pythium, Rhizoctonia and Fusarium. It must be combined with triadimenol (Baytan®) for control of Thielaviopsis.

Thiram Thiram ethylene bisdithiocarbamate (EBDC) fungicide is a broad spectrum contact fungicide. It provides fair to good control of damping off pathogens. It has multiple targets in the biochemical processes of susceptible fungi through inactivation of –SH groups in amino acids, proteins and enzymes. In cotton it is used primarily in seed treatment, both in commercial seed production facilities and in planter box treatments. Thiram formulations are available to treat both acid delinted and fuzzy cottonseed. It provides fair to good broad-spectrum control of the damping-off fungi. It gives good control of Fusarium, and a variety of saprophytic fungi including Rhizopus, Aspergillus, and Penicillium. It also provides fair to good control Rhizoctonia and Pythium. It is not effective against Thielaviopsis and must be mixed with other fungicides to increase efficacy against this seedling pathogen and to increase efficacy against Rhizoctonia and Pythium.

Triadimenol (Baytan®) Triadimenol (Baytan®) triazole fungicide is a narrow spectrum, locally systemic sterol inhibitor that blocks sterol production at the same site than as imidazoles. This attribute gives myclobutanil both preventive and limited curative properties. In cotton, it is applied primarily as a seed treatment fungicide that provides effective control of Thielaviopsis. It is often mixed with other fungicides to provide control of additional fungi that it will not control. A common mixture is with myclobutanil (Nu-Flow M®) for control of Rhizoctonia.

Trichoderma harzianum (T-22 Planter Box®®, T-22G , F-Stop®) Trichoderma harzianum (T-22 Planter Box®® T-22G , F-Stop®) biofungicide is a beneficial microbe, Trichoderma harzianum Rifai strain KRL-AG2 (T-22) which grows on the outside of the plant root to provide prolonged protection against plant root pathogens such as Pythium, Rhizoctonia, Fusarium, Cylindrocladium and Thielaviopsis. The active ingredient is applied at a single application rate of 0.023 lbs./acre as an in-furrow soil treatment or in a slurry to coat seeds.

86 Nematode Control

Nematodes have caused serious damage to Texas cotton. Damage may range from erratic or thin plant stands or plant stunting to death under severe infestations.

Root-knot nematode

The Root-knot nematode, Meloidogyne incognita, infects cotton and many other plants. This nematode is widespread in Texas and is usually found in sandy or sandy loam soils. Laboratory assays of nematodes in Texas cotton show that more than 95 percent of economic infestations of nematodes are by the root-knot nematode.

Causal agent and disease development. Meloidogyne incognita acrita is the principal nematode pest of cotton in Texas. It is an obligate parasite that must complete its life cycle in a plant host, but eggs are persistent and can remain inactive in the absence of a host or in fallow fields from several months to several years. It is most active in the summer when soil temperatures are warm.

As M. incognita larvae enter the plant root, feed, and mature, the surrounding cells of the plant root increase in size and divide causing swellings (galls) on the roots. In cotton, these swellings are usually small and often very inconspicuous. Plants may be heavily infected even though galls are not easily visible. Once cotton plants are infected, the flow of nutrients and water is restricted. Severely infected young plants are often stunted and chlorotic. Infected mature plants do not die, but yields are reduced.

Symptoms. The symptoms caused by root knot vary from slight plant stunting to death in areas of severe infestation. Erratic, thin or skippy stands, particularly in distinct areas of a field, are characteristic. In skip-row cotton, where current rows are laid out perpendicular to the previous year's row, stunted cotton outlining the old rows may be noticed. Root knots are small and should be checked on plants dug with a shovel and not those pulled by hand. Pulling plants often results in just the tap root being extracted and leaves behind feeder roots, which are much more likely to show galls from root-knot nematode infection.

Prevention and control. Crop rotation is the best control method for root-knot nematodes in cotton. A three or four year rotation program with resistant crops is most effective. Because of the wide host range of root-knot nematode, the choice of rotation crops is critical. Melons, watermelon, peppers and beans, and many other vegetable crops are hosts of root-knot nematode and should not be rotated with cotton when M. incognita is a problem. Most of the small grains, such as wheat, oats and barley, are fairly resistant. Rotations to alfalfa or small grains, which are not hosts, are effective, especially in multiple year rotations. Some varieties of sorghum and corn are susceptible to root-knot nematodes and rotations to these crops should include root-knot nematode resistant varieties.

Resistant cotton varieties. Root-knot nematode resistant varieties of cotton are becoming available. Most resistant varieties have been developed for full-season production under irrigation. Few if any are available for short-season or dryland production practices. Nematode resistant varieties suppress initial infection by cotton root knot nematode and reduces yield loss of cotton plants grown in infested soil. Because reproduction of the cotton root-knot nematode on roots of resistant varieties is limited, soil populations in the fall are much lower than the level in soil following susceptible cotton varieties. Although resistant varieties provide excellent protection, producers should not plant them year after year in the same field. Experience with resistance in other crops has shown the root knot nematode populations have the potential to overcome host plant resistance when exposed repeatedly to varieties with the same genetic background.

87 Chemical control. Treatment with nematicides, such as aldicarb (Temik) banded at planting are effective in preventing damage from most root-knot nematode infestations. Preplant soil fumigation with 1,3 Dichloropropene (Telone II) or 1,3-D plus chloropicrin (Telone C-17, Telone C-35) is also effective in reducing nematode infestations but is somewhat more costly than row banded nematicides. Fields to be planted to cotton can be sampled in late fall or early spring and the soils assayed for presence of root-knot nematode. Application of nematicides or fumigation is recommended if greater than 0.5 larvae/cc soil are detectable.

Other nematodes

Of the other nematodes that cause damage to Texas cotton, the reniform nematode, Rotylenchus reniformis, is the most important in cotton production in Texas. It has been found in very small numbers in three counties in the High Plains, but it is most prevalent in the Rio Grande Valley area. Laboratory assays show that between 2 and 3 percent of economic infestations of nematodes are by reniform nematodes. Most of these were observed in the Lower Rio Grande Valley. Other nematode species account for the balance of economic infestations in Texas cotton. Laboratory assays show that lesion (Pratylenchus spp.), spiral (Helicotylenchus spp.), lance (Hoplolaimus spp.), sting (Benlonolaimus spp.) and stunt (Tylenchorhynchus spp.) also have occasionally caused economic losses in Texas cotton. Control practices for these nematodes are similar to those for root-knot nematodes, including crop rotation and chemical control with nematicides or soil fumigants.

88 Nematicides and soil fumigants

1,3-Dichloropropene (Telone II®, 1,3-D) 1,3-D (Telone II®) is a chlorinated hydrocarbon soil fumigant with nematicidal, fungicidal, insecticidal and herbicidal properties, for use on cotton and many other crops prior to planting. Formulations include 94% liquid concentrate, which is applied through chisel injection into the soil, using row banded or overall broadcast treatments. Application rates range from 30 or 40 lbs ai (3 to 4 gallons) to 968 lbs ai (97 gallons) per acre. There is only one application per year. 1,3-D soil fumigation has shown relatively consistent efficacy for nematode management in cotton. It may be used to reduce initial nematode soil population densities prior to cotton planting. Application of the fumigant usually results in significant cotton yield responses in nematode-infested soils. Research over several years has shown an average increase of approximately 35 and 50 pounds of cotton lint per acre for each gallon of 1,3-D applied per acre to root-knot-infested soil. 1,3-D is applied with a single injection chisel to a depth of at least 12 inches beneath the row, seven to ten days prior to cotton planting. Deeper application is acceptable but 1,3-D should not be injected into clay subsoil. Applications shallower than 12 inches have sometimes led to poor nematode management. A range of rates from as little as four to six gallons of 1,3-D per acre have demonstrated effective root-knot nematode control. Three gallons per acre has demonstrated satisfactory control of reniform and sting nematodes. Higher dosages effectively suppress many soil-borne diseases, except Phymatotrichum omnivorum cotton root rot. Regardless of dosage rate, the fumigant should not be applied when the soil is dusty dry or wet. Sealing the chisel application slits immediately after application by bedding, press wheels, culti-packing, fluted coulters, or similar devices is necessary to prevent premature escape of the 1,3-D fumes. In the arid west, higher rates of 1,3-D (Telone II) soil fumigant are necessary to be effective on root-knot nematodes in cotton, and the economic return on the higher rates are presently not competitive with other nematicides.

Chloropicrin + 1,3-D (Telone®® C-17, Telone C-35) Chloropicrin + 1,3-D (Telone®® C-17, Telone C-35) chlorinated hydrocarbon soil fumigant combines 1,3-D and chloropicrin. Chloropicrin is a clear, colorless, oily liquid with a strong, sharp, highly irritating odor. It is a strong lachrymator (tear gas) and serves as a warning chemical with other odorless fumigants. Chloropicrin has been used as an insecticide since 1917 and as a soil fumigant since 1920. The primary use today is for preplant soil fumigation to control soil borne fungi, diseases and nematodes. It is more effective against resistant cysts, sclerotia and hard to kill organisms than 1,3-D by itself. Formulations include 77.9 % 1,3-D plus 16.5 % chloropicrin (Telone®® C-17), 58.5% 1,3-D plus 35% chloropicrin (Telone C-35). The liquid concentrate formulations may be applied through chisel injection into the soil, row banding with incorporation or by overall broadcast treatments also with immediate incorporation. Application rates range from 43 to 968 lbs ai/acre. There is only one application per year. Chloropicrin plus 1,3-D (Telone®® C-17, Telone C-35) soil fumigant offers even more efficacious control of root-knot nematodes in cotton. Although many soil- borne diseases are controlled with this fumigant combination, it does not control Phymatotrichum omnivorum cotton root rot. In the arid west, higher rates may be necessary to control nematodes and soil-borne diseases. Comparatively higher costs per acre for treatment make the return on chloropicrin plus 1,3-D fumigation less attractive than treatment with other nematicides.

Aldicarb (Temik®) Aldicarb (Temik®) oxime carbamate nematicide is highly effective against nematodes when used at higher label rates. See insecticides for chemical characteristics. Aldicarb effectively controls root-knot nematode and other nematodes in cotton and can effectively reduce the incidence of nematode caused Fusarium wilt. When nematodes are at levels that require treatment, aldicarb (Temik) at planting has increased cotton yields. Aldicarb is applied as a 15 percent granular formulation incorporated into two or more inches of soil in a narrow band (four-six-inches-wide) immediately prior to or at-planting. The high return on the investment

89 for treatment of nematodes with aldicarb make this the most attractive treatment of root-knot nematodes throughout the cotton production regions of Texas, including the more arid sections of the state.

Fenamiphos (Nemacur®) Fenamiphos (Nemacur®) is organophosphate nematicide that controls a broad spectrum of nematodes in several important crops. In cotton, fenamiphos is applied as a 15 percent granular formulation incorporated into two or more inches of soil in a narrow band (four-six-inches-wide) immediately prior to or at-planting. There have been no Texas Cooperative Extension evaluations of fenamiphos for management of cotton nematodes.

Metam-sodium (Vapam®®, Nemasol ) Metam-sodium (Vapam®®, Nemasol ) dithiocarbamate soil fumigant is a aqueous solution of sodium N-methyldithiocarbamate used primarily as a soil fumigant and sometimes as a PPI applied non-persistent fungicide and herbicide. It is a general use soil fumigant used for control of a wide variety of nematodes, soil pathogens, insects and weeds. It will control soil-borne species of nematodes and some fungi on a variety of crops. It is used as a general purpose soil fumigant. Highly effective in control of weeds and weed seeds, nematodes, and certain soil fungi. Penetration and effectiveness is improved somewhat by a water seal although this is not necessary. It may be applied through chisel injection into the soil, row banding with immediate incorporation or by overall broadcast treatments also with immediate incorporation. Application rates range from lbs ai/acre. It is the only soil fumigant that can be applied through irrigation equipment. There is only one application per year. Metam-sodium formulations are registered for preplant use on cotton. Metam-sodium is not effective in the control of Phymatotrichum omnivorum cotton root rot. Field tests also have failed to show economic yield increases with treatable populations of root-knot nematodes.

90 Worker Activities

Scouting

Scouting for insect pests and monitoring plant growth and development is the primary activity requiring workers to enter cotton fields during the growing season. Scouting is performed by consultants, Extension Agents-IPM, summer scouts, growers, and industry employees. Summer scouts may be spend 40 or more hours per week in cotton fields.

Manual Weed Control

Hand weeding is less common than in years past primarily as a result of cost of labor. Occasionally workers will perform this task and may use mechanical methods “chopping” or chemical methods by means of a hand-held or backpack sprayer to accomplish ”spot spraying”. Typically these methods will occur later in the season when mechanical cultivation is no longer possible.

Irrigation

The majority of irrigated acres in Texas use sprinkler or some type of overhead irrigation requiring very little worker activity in the fields. Some areas, such as the Lower Rio Grande Valley, use furrow irrigation which requires workers to place and repair irrigation pipe within the field. Workers entering fields for irrigation purposes occurs during a limited portion of the season.

The majority of cotton production occurs through mechanized processes. Tillage, spraying, and harvest are accomplished using motorized equipment usually from an enclosed cab.

91 Conclusions

Education. Educational concerns were identified and used to set priorities. They fell into five general categories. Stakeholder concerns for education centered first on the education of cotton producers, insect scouts, professional crop advisors (PCAs) and others involved in the production chain. Essential education programs vital to these groups included transfer of new technology and the continued evaluation of existing and older technologies.

Pesticide issues took precedence. First, were the continuation of educational programs on pesticide use, safety, drift management, sprayer calibration and application methods. Second, was continued development of educational programs for weed management, identification of herbicide injury, and symptoms of herbicide carryover, herbicide resistance management, identification of herbicide resistance, and the identification of environmental effects that have been misidentified as herbicide resistance.

Third, were insect pest management educational programs on beneficial and pest insect identification, education programs for field scouts and continuing the TPMA/EA-IPM coordinated cotton pest scouting program. Fourth, education priorities included the preservation and expansion of educational resources. Chief among these was the preservation and expansion of the positions of Extension Agents-IPM and Area Specialists as local resources for cotton producers. It also included the restoration of these positions in locations where Extension Agent-IPM positions and Area Specialist positions had been eliminated. It included producer input and cooperation to provide direction and goals for Extension Agents-IPM and District Specialists to develop education programs.

Finally, a set of general educational concerns were used to develop several priorities. These priorities were directed both at cotton production stakeholders and at the general public who have little knowledge of the importance of cotton production and its problems to the Texas economy. Priorities included web-based educational resources, the publication of success stories and the stakeholder support for extension positions in county and district positions, and improving the information network among county, district, and state research and extension personnel.

Regulatory. Advisory committee members expressed concern about the increasingly hostile regulatory environment for agriculture. They noted that the USDA, the EPA, the three groups of the land-grant college system, and the cotton industry need to pro-actively identify research and regulatory needs to address the reliance on certain pesticides and the development of effective alternatives, should they become necessary as a result of EPA's regulatory actions.

Particular concerns emerged about genetically modified cotton varieties. With the development of genetically modified cotton varieties, regulatory concerns about the release of genetically engineered organisms into the environment emerged. The 1986 Coordinated Framework for the Regulation of Biotechnology published by the U.S. Office of Science and Technology Policy (OSTP) remains the basis for regulation today. EPA requires a particular amount of non-Bt cotton to be planted next to Bt cotton to serve as a refuge for insects carrying Bt susceptible genes. Certain exemptions or modifications have been made for pink bollworm eradication programs. As research brings to light more information on transgenic plants, EPA at some point may modify or increase existing regulation of these crops.

EPA's present re-registration of pesticides under the requirements of the Food Quality Protection Act (FQPA) threatens many pesticides essential to cotton production. The Agency's examination of dietary, ecological, residential, and occupational risks focuses heavily on the organophosphate (OP), carbamate and B2 carcinogen groups of pesticides and has created uncertainty as to their future availability to cotton producers. At some point, the EPA may propose to modify or cancel some or all uses of these chemicals on cotton.

92 The regulatory studies that EPA requires registrants to complete may result in some companies voluntarily canceling certain registrations for cotton. Cooperative efforts must be directed at alleviating current high costs of registration and re-registration of limited acreage pesticides that remain valuable to producers.

Particular concern arose regarding the continued registration of effective pesticides, particularly malathion, for which there is no other option for boll eradication. Maintenance and enforcement of state stalk destruction laws and regulations need to remain even after boll weevil and pink bollworm eradication. Continued regulation of seed and enforcement of quarantines for boll weevil management, particularly on the movement of equipment (primarily harvesting) from non-eradicated zones to eradicated zones must continue until boll weevil and pink bollworm have been eradicated.

Committee members regarded it essential to maintain registrations of older insecticides such as dicrotophos, despite decreasing use, to control insects not subject to eradication or controlled by transgenic Bt varieties. It is essential to preserve insecticides necessary to eradicate boll weevil and pink bollworm from affected areas of Texas. It is also essential to maintain the availability and preserve the registrations of seed treatment chemicals. Regulatory concerns also involved evaluating the impact of online pesticide sales on geographical sales reporting.

Other concerns were expressed over rising technology fees for transgenic varieties as well as future availability of conventional cotton varieties. Cotton producers must work together with Extension and Research personnel to maintain registrations of other herbicides for resistance management in view of widespread use of single-herbicide-tolerant varieties. It was also regarded as essential to preserve the registration of 2,4-D for crop destruction, volunteer, and pre-plant weed control.

Research. In the coming years cotton pest management research will be vital to the Texas agricultural economy. Research must continue with both basic and applied research. It is imperative to maintain level or increased support of public research institutions, including the Land Grant College system, the Experiment Station system and Texas Cooperative Extension, which together focus exclusively on the needs of Texas producers and not on broader national marketing imperatives. Cotton pest management research must continue with both basic and applied research in the various aspects of cotton production, including, agronomy, genetics, physiology, weed control, plant diseases and insects. It is also essential to develop risk mitigation measures to reduce human and environmental exposure to pesticides.

With increased use of genetically modified (GM) cotton varieties, research must increase on the extent of shifts in herbicide resistance in weed populations and changes in the weed spectrum due to selection by extensive use of a single herbicide or herbicide class. Research also needs to focus on weed resistance management. Agronomic research must continue to evaluate the efficacy and value of in-season plant growth regulators (PGRs) and the efficacy and value of end-of-season PGRs and defoliants. Cotton breeding programs need to continue research in the development of conventional cotton varieties while also responding to an increased need to identify desirable traits for development or transgenic varieties.

Insect pest management also will require a shift in emphasis if not a change in paradigms following eradication of boll weevil and pink bollworm. Short term research must include effects of eradication practices on beneficial arthropods and on the outbreaks of secondary pests. Long term research must focus on the rising incidence of occasional pests, particularly those not controlled by Bt cotton varieties, including plant bugs, stink bugs, and aphids. There is an increasing need to re-evaluate economic thresholds and sub-threshold infestation levels for insect pests in the light of new varieties and various production systems.

93 The need continues for applied research on the effect of seed treatment insecticides and coated seed technology to reduce costs and optimize profitability. Research also must intensify on cultural and biological controls, utilization of biopesticides, and the identification and use of systemically acquired resistance (SAR) materials.

With the arrival of many new conventional and transgenic cotton varieties, there should be an increased effort to re-examine a systems approach to pest management and a re-evaluation of economic thresholds for all pests of cotton with respect to the new varieties.

Research in disease management must include continued research to identify and evaluate tools for managing cotton root rot. There must be a continued effort to improve the control of seedling diseases. Research must increase into identification of mechanisms and sources of resistance to bacterial blight and the their inclusion in cotton breeding programs. There must also be continued periodic evaluation of seed treatment chemicals and investigations evaluations of new and existing fungicides for the control of cotton leaf rust.

94 Advisory Committee Members

Mr. Bobby Sparks, cotton producer, Mercedes, TX Mr. Joe Pennington, cotton producer, Raymondville, TX Mr. Jimmy Dodson, cotton producer, Robstown, TX Mr. Danny May, cotton producer, Port Lavaca, TX Mr. Dwain Nunley, cotton producer, Port Lavaca, TX Mr. Jeff Stapper, County Extension Agent, Sinton, TX Dr. Robert Lemon, Extension Cotton Agronomist, College Station, TX Mr. Charles Stichler, Extension Agronomist, Uvalde, TX Dr. Roy Parker, Extension Entomologist, Corpus Christi, TX Mr. John Norman, Extension Agent-IPM, Weslaco, TX Mr. Joe Janak, County Extension Agent, Victoria, TX Mr. Dan Fromme, Extension Agent-IPM, Wharton, TX Dr. Steve Livingston, Extension Agronomist, Corpus Christi, TX Mr. Mike McHugh, consultant, Uvalde, TX Dr. Frank Carter, National Cotton Council, Memphis TN Mr. Sam Simmons, Cotton & Grain Producers of the Lower Rio Grande Valley, Harlingen, TX Mr. Jeff Nunley, South Texas Cotton and Grain Association, Victoria, TX Mr. Craig Shook, cotton producer, Corpus Christi, TX Dr. Rodney Holloway, Extension Specialist, College Station, TX

Mr. Larry Turnbough, Trans-Pecos cotton producer, Midland, TX Mr. Sid Long, Southern Region Plains Cotton Growers Association, Dr. Harold Kaufman, Extension Plant Pathologist, Lubbock, TX Dr. Megha Parajulee, TAES Entomologist, Lubbock, TX Mr. Warren Multer, Extension Agent-IPM, Glasscock County, TX Mr. Brett Cypert, National Cotton Council, Sweetwater, TX Mr. Richard Minzenmayer, Extension Agent-IPM, Runnels/Tom Green County Mr. Rodney Ripple, Texas Pest Management Assn./cotton producer, Tom Green County, TX Dr. Tom Fuchs, Extension IPM Coordinator, San Angelo, TX Mr. Barney Pustejovsky, Texas Pest Management Assn./producer, Hill County, TX Mr. Chris Locke, crop consultant, Hockley/Bailey County, TX Dr. Wayne Keeling, TAES Agronomist, Lubbock, TX Dr. Peter Dotray, TAES/TCE/TTU Weed Scientist, Lubbock, TX Mr. Brant Baugh, Extension Agent-IPM, Lubbock, TX Mr. Kerry Siders, Extension Agent-IPM, Hockley/Cochran Counties, TX Dr. James Leser, Extension Entomologist, Lubbock, TX Mr. Rickey Bearden, Plains Cotton Growers, Plains, TX Mr. Roger Haldenby, Plains Cotton Growers, Lubbock, TX Mr. Rick King, National Cotton Council, Lubbock, TX Dr. Steve Toth, NC State University, Raleigh, NC Dr. Randy Boman, Extension Agronomist, Lubbock, TX

Acknowledgments

We wish to acknowledge the contributions of all the Advisory Committee members to this project. The members provided valuable information on production and all aspects of pest management in Texas cotton production. Special thanks are extended to Dr. Roy Parker, Mr. John Norman, Dr. Randy Boman, Dr. Peter Dotray, Dr. Wayne Keeling, Dr. Tom Fuchs, Dr. Jim Leser, Dr. Harold Kaufman, Dr. Terry Wheeler and Dr. Chris Sansone for their significant contributions of time and effort to this project.

95 References

Allen, C. T. 1994. Extension Bulletin B-1511, Pink bollworm management in Texas. Texas Agricultural Extension Service, The Texas A&M University System.

Allen, C. T., E. P. Boring III, J. F. Leser, and T. W. Fuchs. 1995. Extension Bulletin B-1209, Management of cotton insects in the High Plains, Rolling Plains, and Trans Pecos Areas of Texas. Texas Agricultural Extension Service, The Texas A&M University System.

Bartlett, A. C. 1995. Resistance of the pink bollworm to Bt transgenic cotton. Proc. Beltwide Cotton Production and Research Conf., National Cotton Council of America, pp. 766-768.

Baugh, B. A., J. F. Leser, T. A. Doederlein and K. Siders. 2005. Extension Publication E-6, Managing Cotton Insects in the High Plains, Rolling Plains and Trans Pecos Areas of Texas. Texas Cooperative Extension, Texas A&M University System.

Baugh, B. A., J. F. Leser, T. A. Doederlein and K. Siders. 2005. Extension Publication E-6A, Suggested Insecticides for Managing Cotton Insects in the High Plains, Rolling Plains and Trans Pecos Areas of Texas. Texas Cooperative Extension, Texas A&M University System.

Bohmfalk, G. T., R. E. Frisbie, W. L. Sterling, R. B. Metzer and A. E. Knutson. 1982. Extension Bulletin B-933, Identification, biology and sampling of cotton insects. Texas Agricultural Extension Service, Texas A&M University System.

Dennehy, T. J. , G. C. Unnithan, S. A. Brink, B. D. Wood, Y. Carriere, B. Tabashnik, L. Antilla, and M. Whitlow. 2004. Update on Pink Bollworm Resistance to Bt Cotton in the Southwest. National Cotton Council, Memphis, TN.10 pp.

El-Lissy, O., R. T. Staten, and W. Grefenstette. 2005. Pink bollworm eradication plan in the U.S., Updated April, 2005. United States Department of Agriculture, and Plant Health Inspection Service, Riverdale, MD / Phoenix, AZ. 10 p.

Flint, H. M., T. J. Henneberry, and F.D. Wilson. 1995. The effects of transgenic cotton, Gossypium hirsutum L., containing Bacillus thuringiensis toxin genes for the control of the pink bollworm (Saunders) and other arthropods. Southwestern Entomol. 20 (3): 281-292.

Henneberry, T. J., L. F. Jech, T. de la Torre. 2001. Larval mortality of pink bollworm and other lepidopterous pests on NuCotton 33B and Daltapine 5415 cottons. Proc. Beltwide Cotton Production and Research Conf., National Cotton Council of America, 866-868 pp.

Henneberry, T. J., L. F. Jech, T. de la Torre, and J. Maurer. 2002. Pink bollworm (PBW) mortality and Cry1AC toxic protein in NuCOTN 33B (Bt) cotton bolls compared with DPL 5415 cotton bolls http://www.entsoc.org/Protected/AMT/AMT27/Test/M6.asp. In Arthropod Management Tests, K. N. Saxena, [ed.]. 2002. Field and Cereal Crops, Entomological Soc. of Amer., Lanham, MD.

Isakeit, T. 2003. Management of Seedling Diseases of Cotton. Texas Cooperative Extension, Texas A&M University, College Station.

96 Knutson, A., R. D. Parker, G. Moore, J. Benedict and R. L. Huffman. 1997. Extension Bulletin B-1204, Management of cotton insects in the Eastern, Southern and Blackland areas of Texas. Texas Agricultural Extension Service, Texas A&M University System.

Marchosky, R., P. C. Ellsworth, H. Moser, and T. J. Henneberry. 2001. Bollgard® and Bollgard® II efficacy in near isogenic lines of ‘DP 50’ upland cotton in Arizona, pp. 866. In P. Dugger and D. Richter, [eds.] Proc. Beltwide Cotton Conf., National Cotton Council of Amer., Memphis, TN.

Norman, J. W. and A. N. Sparks. 1998. Extension Bulletin B-1210, Management of Cotton Insects in the Lower Rio Grande Valley of Texas. Texas Agricultural Extension Service, Texas A&M University System.

Norman, J. W. 2005. Extension Publication E-7, Managing Cotton Insects in the Lower Rio Grande Valley. Texas Cooperative Extension, Texas A&M University System.

Norman, J. W. 2005. Extension Publication E-7A, Suggested Insecticides for Management of Cotton Insects in the Lower Rio Grande Valley. Texas Cooperative Extension, Texas A&M University System.

Parker, R. D., D. D. Fromme, A. E. Knutson and M. Jungman. 2005. Extension Publication E-5, Managing Cotton Insects in the Southern, Eastern and Blackland Areas of Texas. Texas Cooperative Extension, Texas A&M University System.

Parker, R. D., D. D. Fromme, A. E. Knutson and M. Jungman. 2005. Extension Publication E-5A, Managing Cotton Insects in the Southern, Eastern and Blackland Areas of Texas. Texas Cooperative Extension, Texas A&M University System.

Patin, A. L., T. J. Dennehy, M. A. Sims, B. E. Tabashink, Y-B Liu, L. Antilla, D. Gouge, T. J. Henneberry, and R. T. Staten. 1999. Status of pink bollworm susceptibility to Bt in Arizona. Proc. Beltwide Cotton Production and Research Conf., National Cotton Council of America, pp. 999-996.

Watson, T. F. 1995. Impact of transgenic cotton on pink bollworm and other lepidopteron pests. Proc. Beltwide Cotton Production and Research Conf., National Cotton Council of America, pp. 759-760.

97 Insecticide Efficacy Tables

Table 2. Seed treatment insecticides Insecticide Trade Name Class Oz ai / 100 lb seed Efficacy Acephate Orthene® OP 0.18 (D) G Thiamethoxam Cruiser® N 7.75 (D) E Imidacloprid Gaucho® N 6.4 - 8.0 (D) E Acephate Address® OP 0.18 (P) G

(D) = Applied at delinting, (P) = Planter box treatment

Insecticide classes

BPU = Benzoylphenylurea, C = Carbamate, CD = Cyclodiene, CHC = Chlorinated hydrocarbon, DBH = Dibenzoylhydrazine, FA = Formamidine, MBP = Microbial Biopesticide, N = Neonicotinoid, OP = Organophosphate, OXD = Oxadiazine, PY = Pyrethroid, S = Spinosyn

Efficacy

U = uneffective (<70% control), not used/not registered), F = fair (70-79% control), seldom used, G = good (80-89% control), often used, E = excellent (90-99% control), often used

Table 3. Insecticides applied in-furrow at planting for thrips (Frankliniella spp. and Thrips spp.) Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Address®®/Orthene OP 0.5 - 1.0 G Alidcarb Temik® 15G C 0.3 - 0.45 E Disulfoton Di-Syston® 15G OP 0.6 G Phorate Thimet® 15G OP 0.5 G

98 Table 4. Insecticides applied to foliage for thrips (Frankliniella spp. and Thrips spp.) Insecticide Trade Name Class Lb ai / Acre Efficacy acephate Address®®/Orthene OP 0.09 - 0.18 G Azinphos-methyl Guthion® OP 0.125 F Dicrotophos Bidrin® OP 0.05 - 0.2 E Dimethoate Dimate® OP 0.11 - 0.22 F Methyl parathion Methyl Parathion 4E OP 0.125 - 0.25 F

Table 5. Insecticides for cotton fleahopper (Pseudatomoscelis seriatus) Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Address®®/Orthene OP 0.188 - 0.25 G Chlorpyrifos Lorsban® OP 0.19 - 0.5 G Dicrotophos Bidrin® OP 0.05 - 0.2 E Dimethoate Dimate® OP 0.125 - 0.25 G Imidacloprid Provado®®/Trimax N 0.047 E indoxacarb Steward® OXD 0.09 - 0.11 E Methomyl Lannate® C 0.113 - 0.225 G Methyl parathion Methyl Parathion 4E OP 0.25 F Oxamyl Vydate® C 0.25 G Oxydemeton-methyl Meta-Systox-R® OP 0.25 F Thiamethoxam Centric® N 0.047 E

Table 6. Insecticides for overwintering boll weevil (Anthonomis grandis) Insecticide Trade Name Class Lb ai / Acre Efficacy Azinphos-methyl Guthion® OP 0.25 E Endosulfan Thiodan®®/Phaser CD 0.375-1.5 G Malathion Atrapa®®/Fyfanon OP 0.61 - 0.92 G Methyl parathion Methyl Parathion 4E OP 0.25 - 0.5 G Oxamyl Vydate® C 0.25 E

99 Table 7. Insecticides for grasshoppers (Brachystola magna and Melanoplus spp.) Insecticide Trade Name Class Lb ai / Acre Efficacy Chlorpyrifos Lorsban® OP 0.25 - 0.5 G Cyfluthrin Baythroid® PY 0.031 - 0.044 E Cyfluthrin + Leverage® PY + N 0.032 + 0.047 E Imidacloprid Dicrotophos Bidrin® OP 0.25 G Esfenvalerate Asana® PY 0.03 - 0.05 E Malathion Atrapa®®/Fyfanon OP 0.61 - 0.92 E Zeta-cypermethrin Fury® PY 0.037 - 0.05 E

Table 8. Insecticides for beet armyworm (Spodoptera exigua) and other armyworms Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Orthene® OP .255 G Bacillus thuringiensis Dipel®®,Condor BIO 0.5 - 1.0 F Chlorpyrifos Lorsban® OP 1.0 E Diflubenzuron Dimilin® BP 0.0625 - 0.12 F Indoxacarb Steward® OXD 0.09 - 0.11 G Methamidophos Monitor® OP 0.9 G Methomyl Lannate® C 0.45 G Methoxyfenozide Intrepid® DBH 0.06 - 0.16 E Profenofos Curacron® OP 0.75 - 1.0 E Spinosad Tracer® NA 0.067 - 0.089 E Tebufenozide Confirm® DBH 0.06 - 0.25 G Thiodicarb Larvin® C 0.6 - 0.9 E

100 Table 9. Insecticides for saltmarsh caterpillar (Estigmene acrea) Insecticide Trade Name Class Lb ai / Acre Efficacy Bifenthrin Capture® PY 0.04 - 0.10 E Cyfluthrin Baythroid® PY 0.025 - 0.04 E Cyfluthrin + Leverage® PY + N 0.025 - 0.375 E Imidacloprid Cypermethrin Ammo® PY 0.04 - 0.1 E Deltamethrin Decis® PY 0.019 - 0.03 E Esfenvalerate Asana PY 0.03 - 0.05 E Ethyl parathion Parathion 8E OP 0.5 - 1.0 U Lambda-cyhalothrin Karate® PY 0.02 - 0.03 E Methyl parathion Methyl Parathion 4E OP 0.5 - 1.0 F - G Tralomethrin Scout X-tra® PY 0.018 - 0.025 E Zeta-cypermethrin Fury® PY 0.033 - 0.045 E

Table 10. Insecticides for Lygus bugs (Lygus spp.) Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Address®®/Orthene OP 0.5 - 1.0 F - G Bifenthrin Capture® PY 0.04 - 0.1 E Cyfluthrin Baythroid® PY 0.025 - 0.047 E Cyfluthrin + Leverage® PY + N 0.032 - 0.047 E Imidacloprid Cypermethrin Ammo® PY 0.04 - 0.1 E Deltamethrin Decis® PY 0.013 - 0.05 E Dicrotophos Bidrin® OP 0.5 F - G Dimethoate Dimate® OP 0.25 F Esfenvalerate Asana® PY 0.03 - 0.05 F Imidacloprid Provado®®/Trimax N 0.047 F - G Lambda-cyhalothrin Karate® PY 0.02 - 0.03 E Methomyl Lannate® C 0.225 G Methyl parathion Penncap-M® OP 0.25 F (microcap) Oxamyl Vydate® C 0.25 G Parathion (ethyl) Parathion 8E OP 0.5 - 1.0 U Tralomethrin Scout X-tra® PY 0.016 - 0.02 E Zeta-cypermethrin Fury® PY 0.035 - 0.05 E

101 Table 11. Ovicides for cotton bollworm (Helicoverpa zea) and tobacco budworm (Heliothis virescens) eggs Insecticide Trade Name Class Lb ai / Acre Efficacy Amitraz Ovasyn® FA 0.125 - 0.25 E Methomyl Lannate® C 0.113 - 0.225 E Profenofos Curacron® OP 0.125 - 0.25 G Thiodicarb Larvin® C 0.125 - 0.25 G

Table 12. Microbial insecticides for bollworm/budworm (H. zea/H. virescens) larvae Insecticide Trade Name Class Lb ai / Acre Efficacy Bacillus thuringiensis Condor® MBP 0.5 - 1.67 F Bacillus thuringiensis Dipel® DF MBP 0.5 - 2.0 F Bacillus thuringiensis Dipel® ES MBP 1.0 - 4.0 F Bacillus thuringiensis Javelin® WG MBP 0.5 - 1.5 F

Table 13. Insecticides for bollworm (Helicoverpa zea) larvae Insecticide Trade Name Class Lb ai / Acre Efficacy Bifenthrin Capture® PY 0.04 - 0.1 G Cyfluthrin Baythroid® PY 0.025 - 0.05 E Cyfluthrin + Leverage® PY + N 0.032 + 0.047 E Imidacloprid Cypermethrin Ammo® PY 0.04 - 0.1 F Deltamethrin Decis® PY 0.019 - 0.03 E Esfenvalerate Asana® PY 0.03 - 0.05 G Indoxacarb Steward® OXD 0.09 - 0.11 E Lambda-cyhalothrin Karate® PY 0.025 - 0.04 E Methomyl Lannate® C 0.45 G Methyl parathion Methyl Parathion 4E OP 0.5 - 1.0 F Spinosad Tracer® NA 0.067 - 0.089 E Thiodicarb Larvin® C 0.6 - 0.9 G Tralomethrin Scout X-tra® PY 0.018 - 0.024 G Zeta-cypermethrin Fury® PY 0.033 - 0.045 G

102 Table 14. Insecticides for tobacco budworm (Heliothis virescens) larvae Insecticide Trade Name Class Lb ai / Acre Efficacy Indoxacarb Steward® OXD 0.09 - 0.11 E Methomyl Lannate® C 0.45 G Methyl parathion Methyl Parathion 4E OP 1.25 - 2.0 F Profenofos Curacron® OP 0.5 - 1.0 G Spinosad Tracer® NA 0.067 - 0.089 E Thiodicarb Larvin® C 0.6 - 0.9 G

Table 15. Insecticides for in-season boll weevil (Anthonomis grandis) Insecticide Trade Name Class Lb ai / Acre Efficacy Azinphos-methyl Guthion® OP 0.25 E Bifenthrin1®Capture PY 0.04 - 0.1 E Cyfluthrin1®Baythroid PY 0.025 - 0.05 E Cypermethrin1®Ammo PY 0.04 - 0.1 E Deltamethrin1®Decis PY 0.019 - 0.03 E Dicrotophos Bidrin® OP 0.5 E Endosulfan Thiodan®®/Phaser CD 0.375 - 1.5 G Esfenvalerate1®Asana PY 0.03 - 0.05 G Lambda-cyhalothrin1®Karate PY 0.025 - 0.04 E Malathion Atrapa®®/Fyfanon OP 0.92 - 1.22 E Methyl parathion Methyl Parathion 4E OP 0.25 G Oxamyl Vydate® C 0.25 E Tralomethrin1®Scout X-tra PY 0.018 - 0.024 E Zeta-cypermethrin1®Fury PY 0.033 - 0.045 E 1. Footnote on pyrethroids applied for in-season boll weevil

103 Table 16. Insecticides for aphids in cotton (Aphis gossyppii, A. craccivora and Myzus persicae) Insecticide Trade Name Class Lb ai / Acre Efficacy Buprofezin Applaud® IGR 0.35 E Chlorpyrifos Lorsban® OP 0.25 - 1.0 G Dicrotophos Bidrin® OP 0.25 - 0.5 G Dicrotophos + Bidrin®® + Ovasyn OP + FRM 0.25-0.5 + 0.125-0.25 E Amitraz Dicrotophos + Bidrin®® + Curacron OP 0.25-0.5 + 0.125-0.25 G Profenofos Imidacloprid Provado®®/Trimax N 0.047 G Methomyl Lannate® C 0.225 G Parathion (ethyl) Parathion 8E OP 0.25 - 0.5 U Profenofos Curacron® OP 0.5 F Thiamethoxam Centric® N 0.047 E

Table 17. Insecticides for stink bugs (Euschitus servus, Nezara viridula, Chlorochroa ligata, and others) Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Address®®/Orthene OP 0.72 - 0.80 F - G Bifenthrin Capture® PY 0.04 - 0.1 G Cyfluthrin Baythroid® PY 0.025 - 0.04 E Cyfluthrin + Leverage® PY + N 0.025 - 0.0375 E Imidacloprid Deltamethrin Decis® PY 0.019 - 0.03 E Lambda-cyhalothrin Karate® PY 0.025 - 0.04 E Methyl parathion Methyl Parathion 4E OP 0.5 - 1.0 F - G Oxamyl Vydate® C 0.33 - 0.5 G Parathion (ethyl) Parathion 8E OP 0.5 - 1.0 U Tralomethrin Scout X-tra® PY 0.018 - 0.024 G Zeta-cypermethrin Fury® PY 0.033 - 0.045 G

104 Table 18. Insecticides for pink bollworm (Pectinophora gossyppiella) Insecticide Trade Name Class Lb ai / Acre Efficacy Chlorpyrifos Lorsban® OP 0.75 - 1.0 E Cyfluthrin Baythroid® PY 0.025 - 0.05 E Esfenvalerate Asana® PY 0.03 - 0.05 G Lambda-cyhalothrin Karate® PY 0.02 - 0.03 E Methyl parathion Methyl Parathion 4E OP 0.5 - 1.0 G Methyl parathion Penncap-M® OP 0.5 - 1.0 G (microcap) Tralomethrin Scout X-tra® PY 0.018 - 0.024 E Zeta-cypermethrin Fury® PY 0.033 - 0.045 E

Table 19. Insecticides for cabbage looper (Trichoplusia ni) and other loopers Insecticide Trade Name Class Lb ai / Acre Efficacy Indoxacarb Steward® OXD 0.09 - 0.1 E Methoxyfenozide Intrepid® DBH 0.06 - 0.16 E Spinosad Tracer® NA 0.067 - 0.089 E Bacillus thuringiensis (See Table 12) MBP 1.0 - 4.0 G

Table 20. Acaricides / Insecticides for spider mites (Acari: Tetranychidae) Insecticide Trade Name Class Lb ai / Acre Efficacy Avermectin Zephyr® ML 0.01 - 0.02 E Dicofol Kelthane® CHC 1.0 - 1.5 E Methyl parathion Methyl Parathion 4E OP 0.25 - 0.33 F Parathion (ethyl) Parathion 8E OP 0.25 U Profenofos Curacron® OP 0.5 - 0.75 F - G Propargite Comite® OS 0.8 - 1.6 E

105 Table 21. Insecticides for silverleaf whitefly (Bemisia argentifolii) adult and other whiteflies Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Address®®/Orthene OP 0.5 G Alidcarb1®Temik 15G C 0.3 - 0.45 G Bifenthrin Capture® PY 0.08 E Buprofezin Applaud® IGR 0.35 E Cyfluthrin + Leverage® PY + N 0.032 + 0.047 G Imidacloprid Endosulfan Thiodan®®/Phaser CD 1.0 F Fenpropathrin Danitol® PY 0.08 E Imidacloprid Provado®®/Trimax N 0.047 G

1. Applied in-furrow at planting

Table 22. Insecticides for Cutworms (Rio Grande Valley) Insecticide Trade Name Class Lb ai / Acre Efficacy Bifenthrin Capture® PY 0.04 - 0.1 E Chlorpyrifos Lorsban® OP 0.75 - 1.0 G - E Cyfluthrin Baythroid® PY 0.0125 - 0.025 E Lambda-cyhalothrin Karate® PY 0.02 - 0.03 E Cypermethrin Ammo® PY 0.04 - 0.1 F - G Deltamethrin Decis® PY 0.013 - 0.019 E Esfenvalerate Asana® PY 0.03 - 0.05 F - G Methyl Parathion Methyl Parathion 4E OP 1.0 F Zeta-cypermethrin Fury®®/Mustang Max PY 0.008 - 0.024 F - G

106 Table 23. Insecticides for plant bugs (Creontiades spp.) (Rio Grande Valley) Insecticide Trade Name Class Lb ai / Acre Efficacy Acephate Address®®/Orthene OP 0.5 G Bifenthrin Capture® PY 0.04 - 0.1 E Cyfluthrin Baythroid® PY 0.025 - 0.04 E Cyfluthrin + Leverage® PY + N 0.047 + 0.032 E Imidacloprid Cypermethrin Ammo® PY 0.04 - 0.1 F - G Deltamethrin Decis® PY 0.013 - 0.019 E Dicrotophos Bidrin® OP 0.5 E Dimethoate Dimate® OP 0.25 F - G Esfenvalerate Asana® PY 0.03 - 0.05 F - G Lambda-cyhalothrin Karate® PY 0.02 - 0.03 E Methomyl Lannate® C 0.225 E Methyl parathion Penncap-M® OP 0.5 - 1.0 F (microcap) Oxamyl Vydate® C 0.25 G - E Parathion (ethyl) Parathion 8E OP 0.5 - 1.0 U Tralomethrin Scout X-tra® PY 0.016 - 0.02 G - E Zeta-cypermethrin Fury®®/Mustang Max PY 0.0175 - 0.05 F - G

107 Herbicide Efficacy Tables

Table 24. Herbicides applied post-harvest or pre-plant to control winter weeds Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Glyphosate Roundup GLY 0.375 - 0.75 WeatherMax® E and others Oxyfluorfen Goal® and others DPE 0.2 - 0.4 G Prometryn Caparol® and others TR 0.6 - 0.8 G 2,4-D various labeled PHEN 0.5 -1.0 G products OXY

Herbicide classes

BP = Bipyridilium, CAA = Chloroacetamide, DIP = Cyclohexanedione, DNA = Dinitroaniline, DPE = Diphenyl ether, FOP = Aryloxyphenoxy-propionate GLY = Substituted glycine, IMZ = Imidazolinone, ISX = Isoxazolidinone, NIT = Nitrile, OAS = Organic arsenical, PBZ = Pyrimidinyl(thio)benzoate, PYZ = Pyridazinone, PYR = Pyrazole, SU = Sulfonylurea, TR = Triazine, TZN = Triazolinone, U = Substituted urea

Efficacy / Use

U = unregistered / unused, F = fair, seldom used, G = good, often used, E = excellent, preferred

Table 25. Preplant herbicides applied to control emerged weeds. Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Glyphosate Roundup Weather GLY 0.5 - 2.0 E Max® and other brands MSMA various MSMA generics OAS 2.0 - 3.0 G Paraquat Gramoxone Max® BP 0.6375 - G 1.125 Thifensulfuron-methyl + Harmony Extra® SU 0.015 - 0.080 Tribenuron-methyl + G 0.007 - 0.009 2,4-D various labeled PHENOX 0.5 -1.0 G products Y Glufosinate Ignite® other 0.42 - 0.52 G

108 Table 26. Preplant incorporated (PPI) herbicides. Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Norflurazon Zorial® PYZ 0.48 - 2.0 F Pendimethalin Prowl® and others DNA 0.495 - 1.485 E Trifluralin Treflan® and other DNA 0.5 - 1.25 E brands

Table 27. Preplant incorporated / preemergence herbicides Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Norflurazon Zorial® PYZ 0.5 - 0.8 F Trifluralin Treflan® and others DNA 0.5 - 2.0 G Pendimethalin Prowl® and others DNA 0.495 - 1.485 G

Table 28. Preemergence herbicides Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Diuron Karmex® and others U 0.8 - 1.6 G Fluometuron Cotoran® U 1.0 - 2.0 E S- Metolachlor Dual Magnum® CAA 0.95 - 1.27 G Norflurazon Zorial® PYZ 0.5 - 0.8 F Prometryn Caparol® and others TR 0.8 - 2.4 G Pyrithiobac-sodium Staple® PBZ 0.032 - 0.048 G Clomazone Command® ISX 0.5 - 1.25 F

109 Table 29. Postemergence or Post-directed herbicides Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Trifluralin1®Treflan and others DNA 0.5 -1.0 G Pendimethalin2®Prowl and others DNA 0.495 - 1.5 G S- Metolachlor3®Dual Magnum CAA 0.475 - 1.27 G Prometryn2®Caparol and others TR 0.8 - 1.6 G

Fluometuron2®Cotoran U 1.0 - 2.0 G Diuron2®Karmex and others U 0.5 - 0.75 G Lactofen2®Cobra DPE 0.78 F DMSA2 DSMA OAS 3.0 F MSMA2 MSMA OAS 2.0 F Pyrithiobac-sodium3®Staple PBZ 0.032 - 0.096 G Fluazifop-P-butyl3®Fusilade FOP 0.125 - 0.375 F Fluazifop-P-butyl + Fusion® FOP 0.125 - 0.375 + F Fenoxaprop-P-ehyl3 0.035 - 0.105 Clethodim3®Select DIM 0.094 - 0.125 G Quizalofop3®Assure II FOP 0.034 - 0.083 F Sethoxydim3®Poast Plus DIM 0.094 - 0.375 F Carfentrazone- Aim® TZN 0.016 - 0.025 G ethyl2 Pyraflufen-ethyl2 ET PYR 0.0016 - 0.0033 G Flumioxazin2®Valor N- 0.063 G phenylphth (tank-mixed alimide with glyphosate) Linuron + Diuron2®Layby Pro U 0.25 - 0.38 + G 0.25 - 0.38 Oxyfluorfen2®Goal and others DPE 0.25 - 0.5 F Glyphosate2, 4 Roundup GLY 0.5 - 1.0 E WeatherMax® and others Glufosinate4®Ignite misc. 0.42 - 0.52 E Bromoxynil4®Buctril NIT 0.375 - 0.5 F Trifloxysulfuron- Envoke® SU 0.0047-0.0117 G sodium3 1. Postemergence incorporated 2. Post-directed 3. Postemergence over-the-top 4. Postemergence over-the-top on genetically modified varieties (RR, LL, BXN) resistant to herbicide

110 Table 30. Herbicides applied at layby Herbicide Trade Name Class Lb ai / Acre Efficacy / Use Prometryn Caparol® and others TR 0.8 - 1.6 G Linuron/Diuron Layby Pro® U 0.4 - 0.6 + G 0.4 - 0.6 Diuron Karmex®and others U 0.5 - 0.75 G Fluometuron Cotoran® U 1.0 - 2.0 G MSMA MSMA OAS 2.0 F Pyrithiobac-sodium Staple® PBZ 0.032 - 0.096 G Carfentrazone-ethyl Aim® TZN 0.016 - 0.025 G Pyraflufen-ethyl ET PYR 0.0016 - 0.0033 G Flumioxazin Valor® N- 0.063 G phenylp (tank-mixed with hthalimi glyphosate) de Glyphosate Roundup GLY 0.5 - 1. E WeatherMax® and others

111 Cotton Harvest Aid Chemicals and Plant Growth Regulator Efficacy Tables

Table 31. Herbicides and plant growth regulators (PGRs) applied as harvest aids and weed control agents at boll opening and at harvest of cotton

Harvest aid / PGR Trade Name Class Lb ai / Efficacy Acre Ethephon Prep®and others EG 0.75 - 2.0 G Ethephon + Cyclanalide Finish 6 Pro® EG + CPC 0.75-2.0 G (ethephon) Ethephon + AMADS CottonQuick® EG + 0.75-2.0 G MDS (ethephon) Carfentrazone-ethyl Aim EC® TZN 0.016 - F 0.025 Pyraflufen-ethyl ET® PYR 0.0024 - F 0.0033 Dimethipin Harvade®®, Lint Plus SDT 0.26 - 0.39 G Sodium chlorate Sodium Chlorate 6 Inorganic 3.0 - 9.0 F Tribufos DEF 6®®/Folex OP 0.75 - G 1.125 Thidiazuron Dropp® U 0.1 - 0.4 E Thidiazuron + diuron Ginstar® U 0.05 - 0.13 E + 0.03 - 0.06

Paraquat Gramoxone Max® BP 0.125 - G 0.75 Endothall Accelerate® DCA 0.07 -0.1 G Glyphosate Roundup Weather Max® GLY 0.5 - 2.0 G and others Sodium Cacodylate Leafall® OAS 0.19 - 0.58 F

Classes BP = bipyridilium, CPC = Cyclopropane carboxylate, DCA = dicarboxylic acid, EG = Ethylene generator, GLY = glycine, MDS = Monocarbamide dihydrogen sulfate, OAS = Organic arsenical, OP = Organophosphate, PYR = Pyrazole, SDT = Substituted dithiin, TZN = Triazolinone, U = Substituted urea

Efficacy / Use U = unregistered / unused, F = fair, seldom used, G = good, often used, E = excellent, preferred

112 Table 32. Miscellaneous plant growth regulators applied to cotton during the growing season to regulate the growth and fruiting process. PGR Trade Name Class Lb ai / Acre Efficacy / Use Mepiquat chloride Pix®®/Topit and QA 0.005 - 0.066 Good other generic brands ® Mepiquat chloride + Pix Plus QA + 0.005 - 0.066 + Good Bacillus cereus MBP 6.2 - 7.4 V1081 cfu Mepiquat Pentia® QA 0.026 - 0.154 Good pentaborate 1. cfu = colony forming units of B. cereus. Commercial formulations of Pix® contain a minimum of 3.1 V 108 colony forming units per fluid ounce.

QA = Quaternary ammonium compound

Efficacy (suppression of vegetative growth, increased boll set, increased boll retention)

113 Fungicide and Nematicide Efficacy Tables

Table 33. Fungicides for cotton seed treatment or in-furrow application at planting. Fungicide Trade Name Class Disease Efficacy/Use Metalaxyl Ridomil® ACN P, G E Mefanoxam Apron XL® ACN P E Pentachloronitrolbenzene Terrachlor®, PCNB OC R G, F Iprodione Rovral® DCB R F, U Etridiazole Ethazol®®, Terrazole TDZ R, P G, F Triadimenol Baytan®1TRZ T , R E Azoxystrobin Protégé®®, Quadris STR R E Fludioxonil Maxim® PPY R, F, G E Myclobutanil Nu-Flow M® TRZ T, R G Chloroneb Nu-Flow D®®, Demosan OC R G Captan Captan PTH G F Carboxin Vitavax® ANI R G TCMTB (benzothiazole) Argent®®, Nusan BNZT P, R, F, G G Mancozeb Dithane®® M-45, Manzate EBDC G F Thiram Thiram EBDC G G, F Bacillus subtilis Kodiak® Bio F, R, G U Trichoderma harzianum T-22 Planter Box® Bio G U T = Thielaviopsis basicola; R = Rhizoctonia solani; P = Pythium spp.; F = Fusarium spp.; G = General damping-off pathogens. 1. Effective against Thielaviopsis basicola at higher label rate

Fungicide classes ACN = Acetanilide, ANI = Anilides, Bio = Biofungicide, BNZT = Benzothiazoles, DCB = Dicarboximides, EBDC = Ethylene bisdithiocarbamates, OC = Organochlorines, PPY = Phenylpyrroles, PTH = Phthalates, STR = Strobilurins, TDZ = Thiadiazoles, TRZ = Triazoles

Efficacy

U = poor (<70% control), unregistered/unused, F = fair (70-79% control), seldom used, G = good (80-89% control), used, E = excellent (90-99% control), often used

114 Table 34. Fungicides for cotton foliar diseases. Fungicide Trade Name Class Disease Efficacy/Use Mancozeb Dithane®®, Manzate EBDC LR G

LR = Cotton leaf rust (Puccinia cacabata), A = Alternaria spp., C = Cercospora spp., R = Rhizoctonia spp., S = Stemphyllium spp. B= Bacterial leaf spot, A = Ascochyta gossypii

Efficacy

U = poor (<70% control), unregistered/unused, F = fair (70-79% control), seldom used, G = good (80-89% control), used, E = excellent (90-99% control), often used

Table 35. Soil fumigants and nematicides for nematode control in cotton Nematicide Trade Name Class Rate Efficacy 1,3-Dichloropropene (1,3-D)1®Telone II CHC 3 - 22 gal E2 1,3-D + Chloropicrin Telone C-17®2CHC 3 - 22 gal E Metam-sodium1®Vapam , Nemasol®THC 7 - 100 gal E2 Aldicarb1®Temik C 3.5 - 10 lb3E Fenamiphos1®Nemacur OP 6.5 - 9.8 lb F

1. Nematode species controlled: Lesion (Pratylenchus spp.), Lance (Hoplolaimus spp.), Reniform (Rotylenchus reniformis), Root knot nematode (Meloidogyne incognita acrita), Spiral (Helicotylenchus spp.), Sting (Benlonolaimus spp.), Stunt (Tylenchorhynchus spp.)

Key to nematicide classes

C = Carbamate, CHC = Chlorinated hydrocarbon, OP = Organophosphate, THC = Thiocarbamate

Efficacy

U = poor (<70% control), unregistered/unused, F = fair (70-79% control), seldom used, G = good (80-89% control), used, E = excellent (90-99% control), often used 2. Excellent efficacy against nematodes but seldom used due to high application costs.

3. Applied at planting.

115 Arthropod Pest Species Index

Species Page Acari: Tetranychidae (Spider mites) ...... 10, 48, 49, 105 Achyra rantalis (Garden webworm)...... 21 Acontia dacia (Brown cotton leafworm)...... 49 Agrotis ipsilon (Black cutworm) ...... 17, 106 Agrotis orthogonia (Pale western cutworm)...... 17, 106 Alabama argillacea (Cotton leafworm) ...... 13, 47, 49 Anomis texana (Minor cotton leafworm) ...... 49 Anthonomis grandis (Boll weevil) . . 1,2,9,10 -12,13 -15,21-23,24,25-28,31,34-36,93,99,103 Aphis craccivora (Cowpea aphid) ...... 18, 104 Aphis gossyppii (Cotton aphid) ...... 2, 10, 13, 14, 15, 16, 18, 19, 32, 104 Bemisia argentifolii (Silverleaf whitefly) ...... 13, 14, 15, 20, 21, 106 Bemisia tabaci (Sweetpotato whitefly)...... 20, 106 Brachystola magna (Plains lubber grasshopper) ...... 13, 14, 15, 19, 20, 100 Bucculatrix thuriberiella (Cotton leaf perforator) ...... 11, 49 Chlorochroa ligata (Conchuela stink bug) ...... 1, 3, 13, 14, 30, 45, 104 Chlorochroa sayi (Say's stink bug) ...... 1, 3, 13, 14, 30, 104 Creontiades spp. (Plant bugs)...... 13, 14, 28, 29, 42, 44, 107 Dysdercus suterellus (Cotton stainer) ...... 49 Estigmene acrea (Saltmarsh caterpillar) ...... 11, 13, 21, 48, 101 Euschistus conspersus (Consperse stink bug) ...... 1, 3, 13, 14, 30, 104 Euschistus impictiventris (Western brown stink bug) ...... 1, 3, 13, 14, 30, 45, 104 Euschistus servus (Brown stink bug) ...... 1, 3, 13, 14, 30,45, 104 Euxoa auxiliaris (Army cutworm)...... 17, 106 Feltia subterranea (Granulate cutworm) ...... 17, 106 Frankliniella occidentalis (Western flower thrips) ...... 13, 14, 15, 16, 18, 99 Helicoverpa zea (Cotton bollworm) . . . . . 9-14, 16, 22, 26-27, 31-33, 34, 38, 43, 46-47, 102 Heliothis virescens (Tobacco budworm) ...... 9-14, 16, 22, 31-33, 34, 38, 43, 46, 102 Lygus hesperus (Western tarnished plant bug) ...... 28, 41, 42, 43, 44, 101 Lygus lineolaris (Tarnished plant bug)...... 28, 41, 42, 43, 44, 101 Lygus spp. (Lygus bugs)...... 13, 14, 28, 29, 31, 42, 43, 44, 101 Melanoplus differentialis (Differential grasshopper) ...... 13, 14, 15, 19, 20, 100 Melanoplus femurrubrum (Redlegged grasshopper) ...... 13, 14, 15, 19, 20, 100 Melanoplus packardii (Packard grasshopper) ...... 13, 14, 15, 19, 20, 100 Murgantia histrionica (Harlequin bug) ...... 30, 45, 104 Myzus persicae (Green peach aphid) ...... 18, 104 Nezara viridula (Southern green stink bug) ...... 1, 3, 13, 14, 30, 31 45, 104 Oebalus pugnax (Rice stink bug) ...... 1, 3, 13, 14, 30, 45, 104 Pectinophora gossypiella (Pink bollworm) 1, 2, 9, 11, 12-13, 14-15, 31, 36-39, 40, 41-43,105 Peridroma saucia (Variegated cutworm) ...... 17, 106 Platynota stultana (Omnivorous leafroller) ...... 49 Podisus maculiventris (Spined shouldered stink bug) ...... 1, 3, 13, 14, 30, 45, 104 Pseudatomoscelis seriatus (Cotton fleahopper) ...... 13, 14, 15, 22, 28, 29, 31, 99 Pseudoplusia includens (Soybean looper) ...... 11, 47, 48, 105 Spodoptera eridania (Southern armyworm)...... 49, 100 Spodoptera exigua (Beet armyworm) ...... 11, 13-14, 21, 45-47, 49, 100 Spodoptera frugiperda (Fall armyworm) ...... 11, 13, 21, 49, 100 Spodoptera ornithogalli (Yellowstriped armyworm) ...... 21, 49, 100 Strymon melinus (Cotton square borer) ...... 13, 21, 49 Syngrapha falcifera (Celery looper)...... 47, 105 Thrips tabaci (Onion thrips)...... 13, 15, 99 Trichoplusia ni (Cabbage looper) ...... 11, 47, 48, 105

116 Arthropod Pest Common Name Index

Pest Page Army cutworm (Euxoa auxiliaris)...... 17, 106 Beet armyworm (Spodoptera exigua) ...... 11, 13-14, 21, 45-47, 49, 100 Black cutworm (Agrotis ipsilon) ...... 17, 106 Boll weevil (Anthonomis grandis)..1,2,9,10 -12,13 -15,21-23,24,25-28,31,34-36,93,99,103 Brown stink bug (Euschistus servus) ...... 1, 3, 13, 14, 30,45, 104 Brown cotton leafworm (Acontia dacia)...... 49 Cabbage looper (Trichoplusia ni) ...... 11, 47, 48, 105 Celery looper (Syngrapha falcifera)...... 47, 105 Conchuela stink bug (Chlorochroa ligata) ...... 1, 3, 13, 14, 30, 45, 104 Consperse stink bug (Euschistus conspersus) ...... 1, 3, 13, 14, 30, 104 Cotton aphid (Aphis gossyppii) ...... 2, 10, 13, 14, 15, 16, 18, 19, 32, 104 Cotton bollworm (Helicoverpa zea) ..... 9-14, 16, 22, 26-27, 31-33, 34, 38, 43, 46-47, 102 Cotton fleahopper (Pseudatomoscelis seriatus) ...... 13, 14, 15, 22, 28, 29, 31, 99 Cotton leaf perforator (Bucculatrix thuriberiella) ...... 11, 49 Cotton leafworm (Alabama argillacea) ...... 13, 47, 49 Cotton square borer (Strymon melinus) ...... 13, 21, 49 Cotton stainer (Dysdercus suterellus) ...... 49 Cowpea aphid (Aphis craccivora) ...... 18, 104 Differential grasshopper (Melanoplus differentialis)...... 13, 14, 15, 19, 20, 100 Fall armyworm (Spodoptera frugiperda) ...... 11, 13, 21, 49, 100 Garden webworm (Achyra rantalis)...... 21 Granulate cutworm (Feltia subterranea) ...... 17, 106 Green peach aphid (Myzus persicae) ...... 18, 104 Harlequin bug (Murgantia histrionica) ...... 30, 45, 104 Lygus bugs (Lygus spp.)...... 13, 14, 28, 29, 31, 42, 43, 44, 101 Minor cotton leafworm (Anomis texana) ...... 49 Omnivorous leafroller (Platynota stultana) ...... 49 Onion thrips (Thrips tabaci)...... 13, 15, 99 Packard grasshopper (Melanoplus packardii) ...... 13, 14, 15, 19, 20, 100 Pale western cutworm (Agrotis orthogonia)...... 17, 106 Pink bollworm (Pectinophora gossypiella) 1, 2, 9, 11, 12-13, 14-15, 31, 36-39, 40, 41-43,105 Plains lubber grasshopper (Brachystola magna)...... 13, 14, 15, 19, 20, 100 Plant bugs (Creontiades spp.)...... 13, 14, 28, 29, 42, 44, 107 Redlegged grasshopper (Melanoplus femurrubrum) ...... 13, 14, 15, 19, 20, 100 Rice stink bug (Oebalus pugnax) ...... 1, 3, 13, 14, 30, 45, 104 Saltmarsh caterpillar (Estigmene acrea) ...... 11, 13, 21, 48, 101 Say's stink bug (Chlorochroa sayi) ...... 1, 3, 13, 14, 30, 104 Silverleaf whitefly (Bemisia argentifolii) ...... 13, 14, 15, 20, 21, 106 Southern armyworm (Spodoptera eridania)...... 49, 100 Southern green stink bug (Nezara viridula) ...... 1, 3, 13, 14, 30, 31 45, 104 Soybean looper (Pseudoplusia includens) ...... 11, 47, 48, 105 Spined shouldered stink bug (Podisus maculiventris) ...... 1, 3, 13, 14, 30, 45, 104 Spider mites (Acari: Tetranychidae) ...... 10, 48, 49, 105 Sweetpotato whitefly (Bemisia tabaci)...... 20, 106 Tarnished plant bug (Lygus lineolaris)...... 28, 41, 42, 43, 44, 101 Tobacco budworm (Heliothis virescens) ...... 9-14, 16, 22, 31-33, 34, 38, 43, 46, 102 Variegated cutworm (Peridroma saucia) ...... 17, 106 Western flower thrips (Frankliniella occidentalis)...... 13, 14, 15, 16, 18, 99 Western brown stink bug (Euschistus impictiventris) ...... 1, 3, 13, 14, 30, 45, 104 Western tarnished plant bug (Lygus hesperus)...... 28, 41, 42, 43, 44, 101 Yellowstriped armyworm (Spodoptera ornithogalli) ...... 21, 49, 100

117 Pesticide Index Pesticide Page 1,3-D...... 89 1,3-Dichloropropene ...... 89 2,4-D...... 65 Abamectin...... 50 Acephate...... 50 Acetamprid ...... 51 Address...... 50 Aim ...... 68, 69 Aldicarb...... 16, 51, 89 Allegiance ...... 85 Amitraz ...... 51, 54 Ammo 2.5EC ...... 53 Ammo WSB ...... 53 Apron ...... 85 Apron XL...... 85 Argent ...... 86 Asana ...... 55 Ascend ...... 86 Assure II ...... 68 Avermectin ...... 50 Azinphos-methyl ...... 12, 51 Azoxystrobin ...... 84 Bacillus subtilis ...... 84 Baytan...... 86 Baythroid...... 52 Bidrin...... 54 Bidrin 8E ...... 54 Bifenthrin...... 51 Bollgard (Bt Cry1Ac transgenic cotton) ...... 11, 34, 38, 39, 52, 55, 58, 97 Bollgard II (Bt Cry1Ac + Cry2Ab transgenic cotton) ...... 11, 39, 97 Bromoxynil ...... 68 Buctril ...... 68 Caparol ...... 65, 66, 67, 69 Captan ...... 84 Capture...... 51 Carbofuran ...... 52 Carboxin ...... 84 Carfentrazone ...... 68, 69 Centric ...... 14, 61 Checkmate PBW ...... 56 Chloroneb ...... 84 Chloropicrin + 1,3-D ...... 89 Chlorpyrifos...... 52 Cinch...... 66, 67 Clethodim ...... 68 Clomazone ...... 67 Cobra ...... 67 Comite ...... 60 Command ...... 67 Confirm ...... 61 Cotoran...... 66, 67, 69 Cotton Pro...... 65, 66, 67, 69 Cruiser ...... 61

118 Pesticide Page Cry1Ac (Bt endotoxin)...... 11, 34, 38, 39, 52, 55, 58, 97 Cry1F (Bt endotoxin)...... 11, 39 Cry2Ab (Bt endotoxin)...... 11, 39, 97 Curacron...... 54, 60 Cyfluthrin...... 52 Cygon ...... 54 Cypermethrin ...... 53 Danitol...... 56 De-Fend ...... 54 Decis...... 53 Deltamethrin ...... 53 Demosan ...... 84 Denim ...... 55 Di-Syston ...... 16, 55 Dicofol...... 54 Dicrotophos...... 54 Dimate ...... 54 Dimethoate ...... 54 Direx ...... 66, 67, 69 Disulfoton ...... 16, 55 Dithane M-45 ...... 85 Diuron ...... 66, 67, 69 DSMA ...... 67 Dual Magnum ...... 66, 67 Dual II Magnum...... 66, 67 Emamectin benzoate ...... 55 Endosulfan ...... 55 Envoke ...... 68 Esfenvalerate ...... 55 ET ...... 68, 69 Ethazol ...... 84 ETMT ...... 84 Etridiazole ...... 84 F-Stop...... 86 Fenamiphos ...... 90 Fenpropatrhin ...... 56 Fluazifop + Fenoxaprop ...... 68 Fluazifop ...... 67 Fludioxonil...... 84 Flumioxazin...... 68, 69 Fluometuron ...... 66, 67, 69 Formula 44 ...... 65 Furadan ...... 52 Fury ...... 62 Fusilade DX ...... 67 Fusion...... 68 Fyfanon...... 58 Gaucho Grande ...... 57 Gaucho ...... 16 Glufosinate ...... 65 Glufosinate ...... 68 Glyphosate ...... 65, 68, 69 Goal ...... 65, 68 Gossyplure ...... 56

119 Pesticide Page Gramoxone ...... 65 Guthion ...... 12, 51 Guthion 2E ...... 51 Harmony Extra ...... 65 Ignite...... 65, 68 Imidacloprid ...... 16, 57 Indoxacarb ...... 14, 57 Intrepid ...... 59 Intruder ...... 51 Iprodione...... 85 Karate ...... 57 Karmex ...... 66, 67, 69 Kelthane ...... 54 Knack ...... 60 Kodiak...... 84 Kodiak HB...... 84 Lactofen ...... 67 Lambda-Cyhalothrin ...... 57 Lannate...... 58 Larvin ...... 61 Layby-Pro ...... 68, 69 Leverage...... 57 Linuron + Diuron ...... 68, 69 Lock-on...... 52 Lorsban...... 52 Malathion ...... 58 Mancozeb ...... 85 Manzate D...... 85 Maxim ...... 84 Mefanoxam ...... 85 Metalaxyl...... 85 Metam-sodium ...... 90 Methamidophos ...... 58 Methomyl ...... 58 Methoxyfenozide...... 59 Methyl parathion ...... 59 Monitor ...... 58 MSMA ...... 65, 67, 69 Mustang Max ...... 62 Myclobutanil ...... 85 Nemacur ...... 90 Nemasol ...... 90 No Mate ...... 41 No Mate PBW ...... 56 Norflurazon ...... 66 Nu-Flow D...... 84 Nu-Flow M...... 86 Nu-Flow T ...... 86 Nusan ...... 86 Orthene...... 50 Orthene 75S ...... 50 Orthene 90S ...... 50 Orthene 97PE ...... 50 Orthocide ...... 84

120 Pesticide Page Ovasyn ...... 51, 54 Oxamyl ...... 59 Oxyfluorfen ...... 65 Oxyfluorfen ...... 68 Paraquat ...... 65 PB Rope L ...... 41, 56 PCNB ...... 85 Pendimax ...... 66, 67 Pendimethalin ...... 66, 67 Penncap-M ...... 59 Pentachloronitrolbenzene ...... 85 Phaser ...... 55 Phorate ...... 16, 59 Poast Plus...... 68 Proclaim ...... 55 Profenofos ...... 54, 60 Prometryn ...... 65, 66, 67, 69 Prometryne ...... 65, 66, 67, 69 Propargite ...... 60 Protégé ...... 84 Provado ...... 57 Prowl...... 66, 67

Prowl H2O ...... 66, 67 Pyraflufen-ethyl...... 68, 69 Pyriproxyfen ...... 60 Pyrithiobac ...... 66, 67, 69 Quadris ...... 84 Quizalofop...... 68 Ridomil ...... 85 Ridomil Gold ...... 85 Roundup ...... 65, 68, 69 Rovral ...... 85 S-Metolachlor ...... 66, 67 Scout X-tra ...... 62 Select ...... 68 Sethoxydim ...... 68 Sniper 2E ...... 51 Spinosad...... 14, 61 Staple ...... 66, 67, 69 Steward...... 14, 57 T-22G ...... 86 T-22 Planter Box...... 86 TCMTB ...... 86 Tebufenozide ...... 61 Telone II ...... 89 Telone C-35 ...... 89 Telone C-17 ...... 89 Temik ...... 16, 51, 89 Temik 15G ...... 51 Terraclor ...... 85 Terrazole...... 84 Thiamethoxam ...... 14, 61 Thifensulfuron + Tribenuron ...... 65 Thimet...... 16, 59

121 Pesticide Page Thiodan...... 55 Thiodicarb ...... 61 Thiram ...... 86 Tracer ...... 14, 61 Tralomethrin ...... 62 Treflan ...... 66, 67 Triadimenol ...... 86 Trichoderma harzianum ...... 86 Trifloxysulfuron ...... 68 Trifluralin...... 66, 67 Trilan...... 66, 67 Trimax...... 57 Valor ...... 68, 69 Vapam ...... 90 Vitavax ...... 84 Vydate...... 59 Warrior ...... 57 Weedar...... 65 Weedone ...... 65 WideStrike (Bt Cry1Ac + Cry1F transgenic cotton) ...... 11, 38, 39 Zephyr...... 50 Zeta-Cypermethrin ...... 62 Zorial Rapid...... 66

122