Chapter 37.3. Disease Control

DISEASE MANAGEMENT Part III: Disease Control in the Landscape, Nursery and Turf

Adapted From: Daniel O. Gilrein, Diane Hanwick, Andrew F. Senesac, Irene Trontakis-Bradley, Warren T. Johnson, George W. Hudler, Sandra L. Jensen-Tracy and Paul D. Curtis By Carolyn Klass, Karen L. Snover-Clift and Bert T. Swanson

Diseases and insects do not take vacations, healthy, soil-borne pathogens may be therefore, a continuous vigilance and scouting present in container or B&B stock. program must be developed, implemented and enforced. The best disease management strategy 8. Do not borrow or lend equipment unless it is includes prevention, starting at the time of thoroughly washed with high pressure water propagation. The most important practice in and a bleach or fungicide. preventing the spread of disease during propagation is to propagate from disease-free 9. Avoid plant stress. Avoid over- and under- stock under sanitary conditions. Sterilize watering, and avoid herbicide or pest injury . equipment using 70% isopropyl alcohol, Physan 20 or monochloramine. To prepare 10. Root prune or conduct timely transplanting monochloramine, dissolve 4.6 grams of to reduce transplant shock. ammonium sulfate into one gallon of water and add 34 ml of 5% household bleach. Physan 20 11. Minimize personnel and equipment entries may also be used to disinfect hard surfaces. To into infested plant or soil areas. disinfect cuttings, rinse cuttings in a 15 ppm solution of chlorinated water, and then dip into a Pesticides provide another significant option in 200 ppm concentration of Physan 20. Agrigrom disease management. Growers, landscapers and can be used in continuous flow systems as a home owners must decide whether control is preventive measure. needed when a problem arises and then decide if pesticides are the proper solution for the Further prevention requires the following action: particular situation. When pesticides are applied, thoroughly spray the trunk, limbs fruit and both 1. Grow disease-resistant cultivars. sides of the leaves just to the point of runoff. Spray should be applied when there is no wind to 2. Implement proper site preparation. assure thorough coverage and to minimize spray drift. Do not spray during rain or when rain is 3. Remove infected tissue to reduce the amount expected within several hours. If rain does occur of inoculum present. after spraying, sprays that are not rain-fast should be reapplied. Treatments listed as 4. Prune and handle infected plants only during “dormant” should be applied just before dry periods. Disinfect tools in a 70% alcohol budbreak, but when temperatures are above 40°F. or a 10% bleach solution between plants. Chemical control of diseases in trees, shrubs, herbaceous perennials and turf is a continuously 5. Remove infected plants from windbreaks changing science. Disease control chemicals and surrounding areas to prevent the spread consist of fungicides, bactericides, nematicides, of inoculum to susceptible nursery plants. algaecides and fumigants. They can be of natural or synthetic origin. They can be applied 6. Monitor and scout plants closely for signs as dusts, liquid sprays, aerosol sprays or and symptoms of disease. fumigants. Chemical controls for viruses do not exist. Disease control responses to each 7. Avoid accepting uncertified nursery stock. chemical varies with the chemical, the chemical Although the plant material may appear formulation, the chemical concentration, the pH

37.3-1 1106 of the water, the host plant, the host plant that disease on that species. This is not an all condition, the site, the cultural practices, the inclusive list. Refer to the References at the end applicator, the application equipment, the of Part IV of this chapter for information on disease, the disease stage, the history of previous additional species, diseases and chemicals. control measures, the temperature, the humidity, Table 5 provides chemical names, trade names and other climatic and miscellaneous factors. It and EPA Registration Numbers for chemical is absolutely essential that the applicator controls of diseases in turf. understand all of these factors prior to the application of any pesticide. This pertains to the Table 6 provides a turf disease control guide. home owner and to the professional applicator. This guide is more applicable to landscape turf It is absolutely essential that any applicator than golf course turf or sod farm turf. This is not always read and understand the pesticide an all inclusive list. Refer to the References at label prior to any pesticide application on any the end of Part IV of this chapter for information plant for any reason. on additional diseases and chemicals.

The following tables provide information on Refer to the Chapter on Pesticide Management disease control chemicals for use by the home for information on pesticide labels, use and owner and by the professional in landscape, safety. nursery and turf situations. Table 1 provides a limited fruit tree disease spray program for the A REMINDER home owner. Table 2 provides chemical and The information given in this publication is trade names of disease control chemicals that can for educational purposes only. Reference to be used by the home owner. Some of these commercial products or trade names is made chemicals are easier and safer to use than others, with the understanding that no discrimination so when in doubt about a chemical’s legal, is intended and no endorsement by the appropriate or safe use, always contact a Minnesota Nursery and Landscape professional applicator. Association or the Minnesota Extension Service is implied. A complete list of brand Table 3 provides information on fungicides, names is not included and inclusion or bactericides and nematicides for professional use exclusion does not constitute any claim or on trees, shrubs and perennials in nurseries and endorsement about product effectiveness. in the landscape. This information includes the The reader is reminded that it is illegal to use EPA Registration Number and the Restricted any pesticide for any purpose or on any plant, Entry Interval (REI) for the chemicals listed. which is not specifically stated on the label. For the safety of individuals, the environment, Table 4 provides a plant disease management and the continued use of valuable products, it and control guide for trees, shrubs and is critical to understand the requirements, the herbaceous perennials. The table lists plant procedures and the products. Read, species followed by diseases prevalent to that understand and follow the label. It’s the law! species, plus remarks relevant to the control of

Table 1. Guidelines for a limited fruit tree disease spray program for the home owner. From: Klass, C. and K.L. Snover-Clift. 2005. Pest Management and the Home Part II. 2005- 2006 Pesticide Guidelines. Cornell University Cooperative Extension.

Disease Pest Management Practice Apple Scab Plant resistant varieties. Apply Thiophanate-methyl per label directions.

Cedar-apple Rust A major problem during wet seasons. Apply Myclobutanil per label directions.

Plum Curculio Apply Surround or a Multi-Purpose Fungicide at petal fall and 10 days later.

37.3-2 1106 Table 2. Fungicides and bactericides for homeowner use1.

Chemical Trade Name Chemical Class Oral LD50 Signal Word Azoxystrobin Heritage Fungicide (Spray drift is Strobilurin Caution phytotoxic to some apple varieties.) Bacillus subtilus Serenade Garden RTU2 Microbial Caution (suppression for some diseases.) Basic Cupric Lilly Miller Microcop, Dexol Inorganic Caution or Sulfate Bordeaux, Basicop, Bonide Cooper Warning Spray/Dust (Not all labels have all uses.) Captan Hi-Yield Captan, Captan Garden Dicarboximides 8,400 to 15,000 Danger Spray, Bonide Captan mg/kg Chitosan Elexa-4 Miscellaneous (Chitin) Chlorothalonil Bonide Fung-onil MPF3 Concentrate, Substituted Aromatic Caution or Bonide Fung-onil, Bravado Warning Fungicide, Garden Disease Control Concentrate, Ortho MPF Daconil 2787, Gordon's MPF, Maxide Concentrate MPF, Lesco Manicure T/O Flowable, Garden Tech RTU MPF Copper Lilly Miller Kop-R-Spray Inorganic Caution Ammonium Carbonate Copper Salts of Prescription Treatment Camelot1, Inorganic Caution Fatty & Rosin Liquid Copper Fungicide Acids Copper Hi-Yield Bordeaux Inorganic Caution (Metallic) Copper Sulfate Phyton 271 Inorganic Severe skin & Danger Pentahydrate eye irritant Fosetyl-Al Monterey Aliette, Aliette WDG Brand Organophosphate Caution Fungicide Jojoba Oil E-Rase Concentrate, E-Rase RTU Oils Caution Lime Sulfur Hi-Yield Lime Sulfur, Lilly Miller Inorganic Caution or (Calcium Polysulfide Summer & Dormant Danger Polysulfide) Spray Mancozeb Protect DF, Protect T/O Ethylenebisdithio- Caution carbamate (EBDC) Metalaxyl-m Subdue GR, Subdue MAXX1 Acyclalemines Caution (Mefenoxam) Myclobutanil Spectracide Immunox MPF Caution

37.3-3 1106 Table 2 (Continued). Fungicides and bactericides for home owner use1.

Chemical Trade Name Chemical Class Oral LD50 Signal Word Neem Oil Various Products Botanical Caution (Clarified Hydrophobic neem Oil) Oil, Petroleum Sunspray Ultra Fine Year-round Oil Refined Petroleum Caution Distillate Pentachloro- Terraclor 75% WP Substituted Aromatic nitrobenzene (PCNB or Quintozene) Potassium Milstop, Armicarb, Remedy Bicarbonate Caution Bicarbonate Propiconazole Bonide Infuse Systemic Disease Warning Control, Ferti-lome Liquid Systemic Fungicide Streptomyces Mycostop Biofungicide Microbial Caution griseoviridis Streptomycin Ferti-Lome Fireblight Spray (May be Microbial Caution Sulfate used for crown gall on roses.) Sulfur Bonide Sulfur Plant Fungicide, Hi- Inorganic Caution Yield Dusting Wettable Sulfur, Lilly Miller RTU MPF Thiophanate- Cleary's 36, Cleary's 3336F1 Dithiocarbamate Caution Methyl (Landscape Plants); Topsin M 70WP (Landscape (Fruits and Vegetables); plants, some Thiophanate-methyl 85 WDG (Fruits fruits) and Vegetables) Thiophanate- Tops MZ Potato Seed Piece Dithiocarbamate Caution Methyl + Treatment Mancozeb Thiram Spotrete 75 WDG Dithiocarbamate Caution Trichoderma Plantshield Biological Foliar & Root Microbial Caution harzianum Fungicide, T-22 Planter Box Biological Fungicide Triforine Rosepride Rose & Shrub Diseases, Piperazine >16,000 mg/kg Danger Rosepride Funginex, Rose & Shrub Diseases 1 Products in bold are legal to use by the home owner, but they may not ideal or easily used by the home owner. 2 RTU = Ready To Use. 3 MPF = Multi-Purpose Fungicide.

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Table 3. Fungicides, bactericides and nematicides for use on trees, shrubs and herbaceous perennials in nurseries and in the landscape. From: Gilrein, D.O., D Hanwick, A.F. Serneac, I. Trontakis-Bradley, W.T. Johnson, G.W, Hudler, S.L. Jensen-Tracy and P.D. Curtis. 2005. 2005 Pest Management Guide for Commercial Production and Maintenance of Trees and Shrubs. Cornell University Cooperative Extension.

Chemical Name EPA Registration Restricted Entry Trade Name 1 Number Site Use2 Interval3(Hours)

Azoxystrobin Heritage Fungicide 100-1093 N, L 4 Remarks: Azoxystrobin is in the Strobilurin chemical class. To discourage development of resistant pests, alternate sprays with another product that has a different mode of action every one or two treatments, as directed on the label.

Calcium Polysulfide Lime Sulfur Solution 72-19 N 48 Remarks: Broad-spectrum protectant fungicide. May be phytotoxic to some plant species if temperature exceeds 75°F at application.

Chlorothalonil Bravo Ultrex 50534-201-10182* N 48 Bravo Ultrex Agriculture Fungicide 50534-201-100* N 12 Bravo Weather Stik 50534-188-10182* N 48 Bravo Weather Stik Agric. Fungicide 50534-188-100* N 12 Concorde 72167-24-1812 N, L 12 Concorde DF 72167-25-1812 N, L 12 Daconil Ultrex 50534-202-10182 N, L 48 Daconil Ultrex Turf Care 50534-202-100 N, L 12 Daconil Weather Stik 50534-209-100 N, L 12 Daconil Weather Stik 50534-209-10182 N, L 48 Daconil Zn 50534-211-10182 N, L 48 Daconil Zn Flowable 50534-211-100 N, L 48 Equus 720 1812-437* N 12 Equus DF 1812-440* N 12 Manicure 6 Flowable 50534-219-100 N, L 12 Manicure T&O Flowable 60063-9-10404 N, L NA4 Manicure Ultrex 50534-202-10182 N, L 48 Manicure Ultrex T&O 50534-202-100 N, L 12 Remarks: Chlorothalonil labels are extremely variable. Before purchasing, be certain product is labeled for both the host and the disease to be controlled. Where noted (*), conifers are the only landscape plants appearing on product labels. Bravo Weather Stik (EPA Reg. No. 50534-188) has a second registration number for Ploioderma needlecast caused by Ploioderma lethale. Where a 12-hour REI is recommended, see additional precautions required for 6.5 days after treatment.

Chlorothalonil + Fenarimol Twosome 10404-60 N, L 48 Remarks: Broad-spectrum fungicide with surface-active protection and some systemic effect.

Chlorothalonil + Thiophanate-Methyl Spectro 90 WDG 1001-72 N, L 12 Remarks: Broad-spectrum fungicide for control of specific leaf spot, rust, scab, and blight diseases.

37.3-5 1106

Table 3 (Continued). Fungicides, bactericides and nematicides for use on trees, shrubs and herbaceous perennials in nurseries and in the landscape. From: Gilrein, D.O., D Hanwick, A.F. Serneac, I. Trontakis-Bradley, W.T. Johnson, G.W, Hudler, S.L. Jensen-Tracy and P.D. Curtis. 2005. 2005 Pest Management Guide for Commercial Production and Maintenance of Trees and Shrubs. Cornell University Cooperative Extension.

Chemical Name EPA Registration Restricted Entry Trade Name Number Site Use Interval (Hours)

Copper, Elemental Basicop 1812-300 N, L 24 Remarks: General protectant fungicide and bactericide.

Cooper Hydroxide Kocide 101 1812-288 N, L 24 Kocide DF 1812-334 N, L 24 Kocide LF 1812-338 N, L 24 Kocide 2000 1812-358 N, L 24 Kocide 4.5 LF 1812-303 N, L 24 Kocide 2000 T/N/O 1812-358 N, L 24 Remarks: General protectant fungicide of leaf diseases. May be toxic to foliage of some deciduous trees and shrubs.

Cooper Hydroxide + Mancozeb Junction 1812-360 N, L 24 Remarks: Combined properties of cooper hydroxide and Mancozeb cover a broad list of disease pests on landscape plants. Phytotoxicity may occur if Junction is applied in a spray solution with a pH below 6.5.

Copper Salts of Fatty and Rosin Acids Camelot 1812-381-499 N, L 12 Remarks: General protectant fungicide and bactericide.

Copper Sulfate Pentahydrate Phyton 27 49538-2 N, L 24 Remarks: General protectant fungicide and bactericide.

Dazomet Basamid Granular 7969-99 N, L 24 Remarks: Soil fumigant which works as a nematicide, fungicide, and herbicide for pre-plant control of some nematode species as well as pathogenic fungi that may cause wilt, damping off, or root rot such as Pythium sp., Fusarium sp., Rhizoctonia sp., Phytophthora cactorum, and Verticillium albo-atrium. See label for complete list of nematodes and soil-borne fungi that may be controlled. Basamid Granular is toxic to plants. It may be used when renovating soils in nurseries or landscape sites, but it must not be used within 3 to 4 feet of living plants. Do not apply within the drip line of trees or shrubs.

Debacarb + Carbendazim Fungisol 7946-14 L NA Remarks: Systemic fungicide used by injection for control of specific diseases of landscape plants.

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Chemical Name EPA Registration Restricted Entry Trade Name Number Site Use Interval (Hours)

Etridiazole Terrazole 35% WP 400-416 N 12 Truban 30% WP 58185-7 N 12 Truban 25% EC 58185-8 N 12 Remarks: Apply to soil for control of Pythium and Phytophthora root rots, damping off, and stem rot on many species of woody plants.

Fenarimol Rubigan EC 62719-134-67690 N 12 Remarks: Systemic action. Use to control Black Spot on container and field-grown roses. See label precautions.

Fosetyl-Al Aliette WDG 432-890 N, L 12 Monterey Aliette 264-556-54705 N, L 12 Remarks: Soil drench for control of Phytophthora and Pythium. Foliar spray for suppression of fire blight.

Horticultural Oil Ultrafine Oil 862-23-499 N, L 4 Stylet Oil 65564-1 N, L NA Remarks: Usually used for control of insect pests on many crops in greenhouses and outdoors. Also registered for control of powdery mildew on roses and other landscape plants.

Iprodione Chipco 26019 Flo 432-888 (Aventis) N, L 12 Chipco 26019 Flo 432-888 (Bayer) N, L 12 – 24 Chipco 26019 Brand Fungicide 432-889 N, L 12 – 24 Chipco 26019 N/G 432-889 N 12 – 24 26 GT Fungicide 432-888 N, L 12 – 24 Sextant 51036-361-59807 N, L 12 – 24 Remarks: Broad-spectrum fungicides for control of Botrytis on labeled plants. Some products are not for residential use; see label.

Kresoxim-Methyl Cygnus 7969-124 N 12 Cygnus 50 WG 7969-124-58185 N 12 Remarks: Acts mainly as a preventive fungicide against mildew, rust, scab, and some leaf spots as noted on label. See list of intolerant plants. Kresoxim-Methyl is of the Strobilurin chemical class. To discourage development of resistant pests, alternate sprays with another product with a different mode of action between every one or two treatments, as directed on the label.

37.3-7 1106

Chemical Name EPA Registration Restricted Entry Trade Name Number Site Use Interval (Hours) Mancozeb 4 Flowable 707-156-10404 N, L 24 Dithane 4 SC 62719-396 N, L 24 Dithane 75 DF Rainshield 62719-402 N, L 24 Dithane DF Rainshield 62719-402* N 24 Dithane F-45 62719-396 N, L 24 Dithane M-45 62719-387* N 24 Fore 80 WP Rainshield T&O 62719-388 N 24 Fore WSP Rainshield T&O 62719-422 N 24 Mancozeb DG 707-180-10404 N, L 24 Pentathlon DF 1812-414 N, L 24 Pentathlon LF 1812-416 N, L 24 Protect T/O 1001-65 N, L 24 Remarks: Broad-spectrum fungicide effective against many foliar diseases and flower and twig blights. Much label variation exists and some labels contain recommendations for management of pathogens of landscape plants that are not found on other Mancozeb labels. If purchasing a product to treat a specific pest, be certain that the product is labeled for that pest. Where noted (*), conifers are the only landscape plants that appear on product labels.

Mancozeb + Myclobutanil Manhandle 707-235-10404 N, L 24 Manhandle 61719-418-10404 N, L 24 Remarks: Broad-spectrum systemic fungicide with protective or curative properties against labeled pathogens.

Mancozeb + Thiophanate-Methyl Zyban WSB 58185-31 N, L 24 Remarks: Broad-spectrum fungicide effective against many foliage diseases and flower and twig blights. This provides surface action of Mancozeb supplemented with systemic action of Thiophanate-Methyl.

Maneb Pentathlon 1812-251 N, L 24 Remarks: Broad-spectrum fungicide effective against many foliage diseases.

Metalaxyl-M (Mefenoxam) Subdue MAXX 100-796 N, L When spray dries. Subdue GR 100-794 N, L When spray dries. Subdue WSP 100-795 N, L When spray dries. Remarks: Systemic fungicide for control of Phytophthora root pathogens of Rhododendron and other landscape plants

Myclobutanil Eagle 40 WP 62719-417 N, L 24 Eagle 20 EW 62719-463 N, L 24 Laredo EC 62719-412 L 24

37.3-8 1106

Chemical Name EPA Registration Restricted Entry Trade Name Number Site Use Interval (Hours)

Myclobutanil (Continued) Systhane WSP 62719-432 N 24 Remarks: Broad-spectrum fungicide for control of leaf, flower, and twig blights.

Myrothecium Verrucaria, Dried Fermentation Solids and Solubles DiTerra WDG 73049-55 N 4 DiTerra DF 73049-67 N 4 Remarks: Nematicide for pre-plant, planting, and post-plant suppression of labeled nematode species.

Neem Oil, Clarified Hydrophobic Triact 70 70051-2-59807 N, L 4 Triact 70 EC 70051-2 N, L 4 Remarks: For control of black spot of rose, powdery and downy mildews, scab, and rust on many plant species. Do not apply to rose blossoms or to other sensitive plants listed on label. Follow label directions to avoid making applications that may cause phytotoxicity.

Phosphoric Acid Magellan 228-337 N, L 4 Remarks: For control or suppression of Phytophthora, Pythium, downy mildew, and some bacterial blights on labeled hosts.

Potassium Bicarbonate Armicarb 100 5905-541 N, L 4 Milstop Broad Spectrum 70870-1-68539 N, L 1 Remarks: Fungicide for control of powdery mildew and Botrytis on a wide variety of plants.

Propamocarb Hydrochloride Banol T&O 432-942 N 24 Remarks: Fungicide for control of Pythium and Phytophthora on labeled plants.

Propiconazole Banner MAXX 100-741 N, L 24 Alamo 100-741 L NA Propiconazaole PRO 51036-403 N, L 24 Shepherd Fungicide 69117-3 L NA Spectator T/O 62719-346-10404 N, L 24 Remarks: Systemic fungicide for control of many foliar diseases. Alamo and Shepherd are usually applied via specific trunk injection systems.

Thiabendazole Hypophosphite Arbotect 20-S 100-892 L NA Remarks: Systemic fungicide for injection into elms for Dutch Elm Disease and Sycamore Anthracnose control. Special training in injection techniques is required.

37.3-9 1106

Chemical Name EPA Registration Restricted Entry Trade Name Number Site Use Interval (Hours)

Thiophanate-Methyl Cleary’s 3336F 1001-69 N, L 12 Cleary’s 3336 WP 1001-63 N, L 12 Fungo Flo 58185-33 N, L 12 Fungo 50 WSB 58185-30 N, L 12 Remarks: Broad-spectrum systemic fungicide for control of many leaf diseases and shoots blights.

Thiophanate-Methyl + Etradiazole Banrot 40% WP 58185-10 N, L 12 Banrot 8G 58185-23 N, L 12 Remarks: Soil drench for control of soil-borne pathogenic fungi in the genera Phytophthora, Pythium, Fusarium, Rhizoctonia, and Thielaviopsis commonly occurring on recently stuck cuttings or new seedlings.

Triadimefon Bayleton 50 T/O 3125-491 L NA Strike 50 WDG 3125-529-59807 N, L 12 Systemic Fungicide containing 50% Bayleton 3125-491-10404 L NA Remarks: Broad-spectrum fungicide with some systemic activity for control of foliage diseases and some rusts.

Trichoderma harzianum var. Rifai Rootshield Granules 68539-3 N, L NA Remarks: Biological fungicide for use in nursery planting media or upon transplanting landscape plants to protect them from root pathogens such as Cylindrocladium, Fusarium, Pythium, Rhizoctonia, and Thielaviopsis.

Trifloxystrobin Compass Fungicide 3125-560 N, L 12 Compass O 50WDG 3125-560-59807 N, L 12 Remarks: Trifloxystrobin acts mainly as a preventive fungicide. Trifloxystrobin is of the Strobilurin chemical class. To discourage development of resistant pests, alternate sprays with another product with a different mode of action every one or two treatments, as directed on the label.

1W or WP = Wettable Powder; E or EC = Emulsifiable Concentrate; F, FL, or Flo = Flowable; LF = Liquid Flowable; DF = Dry Flowable; DG or DWG = Water Dispersible Granules; WSP or WSB = Water Soluble Packet or Bag; G = Granular; S = Soluble; AS = Aqueous Suspension; SC = Soluble Concentrate; T/O or T&O = Turf and Ornamental. 2Site Use: N = Nursery – Field and Container; L = Landscape – Residential and Commercial. 3REI = Restricted Entry Interval – Applies to nursery uses under the Worker Protection Standard, 40 CFR Part 170. 4NA = Not Applicable.

37.3-10 1106

Table 4. Plant disease control guide for landscape plants. From: Gilrein, D.O., D Hanwick, A.F. Serneac, I. Trontakis-Bradley, W.T. Johnson, G.W, Hudler, S.L. Jensen-Tracy and P.D. Curtis. 2005. 2005 Pest Management Guide for Commercial Production and Maintenance of Trees and Shrubs. Cornell University Cooperative Extension.

Plant and Disease Disease Prevention and Control

Abies (True Fir) Cankers: Leucostoma, Cytospora, Keep trees fertilized and watered, and avoid all wounding. If and Valsa infection occurs, remove and destroy all diseased parts, disinfecting tools between cuts. Do not prune in wet weather.

Root Rot: Phytophthora cinnamomi Do not plant Frazer fir on heavy, wet soils. In nurseries, infected stock can be treated with Metalaxyl-m, Etridiazole, or Banrot.

Needle Rust: Uredinopsis Encourage good circulation in nurseries and Christmas tree fields. Eliminate ferns by mowing or with herbicides. Apply Triadimefon to fir at budbreak and twice thereafter at 10- to 14-day intervals. Do not apply Triadimefon on Abies concolor.

Acer (Maple) Anthracnose: Discula Destroy or compost fallen infected leaves in autumn. Sprays are usually not needed. If disease was severe the previous year and cool, wet conditions prevail in spring, spray with elemental copper, Camelot, Chlorothalonil, Thiophanate- Methyl, Spectro 90WDG, Protect T/O, or Junction at budbreak and twice thereafter at 7- to 14-day intervals, or per label directions.

Cankers: Leucostoma, Cytospora, Avoid injuries; keep trees well watered and fertilized to Valsa maintain resistance to infection. Prune in late spring or early summer. Remove and destroy cankered branches.

Dieback: Decline Avoid exposure to road salt. Keep trees well watered, especially from May through August. Aerate compacted soil in the root zone. Prune dead branches.

Tar Spots: Rhytisma Destroy or compost fallen leaves in autumn. Disease is usually not severe except on Norway maple where fungicide sprays may be needed to preserve a tree’s appearance. If so, apply Triadimefon, Mancozeb, or Junction at budbreak and twice thereafter at 7- to 14-day intervals per label directions.

Verticillium Wilt: Verticillium dahliae Refer to Footnote Number Two (2) on “Verticillium Wilt” at the end of this Table.

Aesculus (Horsechestnut, Buckeye) Leaf Blotch: Guignardia aesculi Symptoms occur so later in the season that the disease rarely (Conidial state = Phyllosticta threatens tree health. Where the appearance of an infected tree sphaeropsoidea) becomes intolerable, spray with Mancozeb, Junction, Chlorothalonil, Twosome, Spectro 90 WDG, Manhandle, or Maneb two to four times at 10 to14-day intervals beginning

37.3-11 1106

Table 4 (Continued). Plant disease control guide for landscape plants. From: Gilrein, D.O., D Hanwick, A.F. Serneac, I. Trontakis-Bradley, W.T. Johnson, G.W, Hudler, S.L. Jensen-Tracy and P.D. Curtis. 2005. 2005 Pest Management Guide for Commercial Production and Maintenance of Trees and Shrubs. Cornell University Cooperative Extension.

Plant and Disease Disease Prevention and Control

Aesculus (Continued) when buds open. The following species or varieties are reported to be resistant: Aesculus x carnea, A. glabra var monticola, A. glabra var. sarggentii, A. parviflora, and A. parviflora var. serotina.

Amelanchier (Shadbush, Serviceberry) Leaf Spot: Entomosporium Symptoms occur late in the season and the disease is rare enough that management is usually not needed. ‘Autumn Brilliance’ and ‘Magnificents’ are resistant.

Rust: Gymnosporangium Eliminate nearby red cedar and common juniper to whatever extent practical. Spray with Myclobutanil when orange rust masses appear on juniper and thereafter at 7- to 14-day intervals per label directions.

Betula (Birch) Leaf Rust: Melampsoridium betulinum Control is usually not necessary because the disease is rare and appears late in the season shortly before normal leaf fall. Where disease is intolerable, the following year apply Triadimefon, Junction, Mancozeb, or Myclobutanil at budbreak and twice thereafter at 7- to 14-day intervals per label directions.

Buxus (Boxwood) Leaf Spot: Macrophoma candollei Prune infected branches back to healthy wood. Fertilize and protect from winter injury to maintain vigor.

Carpinus (Hornbeam) Anthracnose: Gnomoniella carpinea Disease is occasionally severer in wet years, but rarely threatens tree health unless cankers occur on main stems on first- or second-year stock. Apply Fungo-Flo as new shoots begin to elongate in spring and twice again at 10- to 14-day intervals. Excess fertilization, especially with nitrogen, may increase disease incidence.

Carya (Hickory) Anthracnose: Gnomonia caryae Destroy fallen leaves in autumn. Symptoms occur so late in the season that tree health is not threatened and sprays are usually not necessary. In unusually severe cases, apply Mancozeb or Junction at budbreak and twice thereafter at two- week intervals to reduce disease incidence.

Downy Leaf Spot: Microstroma Apply Junction at first sign of disease and again at 7- to 14- juglandis day intervals as needed.

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Plant and Disease Disease Prevention and Control

Catalpa (Catalpa) Leaf Spots: Several Fungi Sprays usually not necessary. Destroy fallen leaves.

Celtis (Hackberry) Witches’-Broom: Sphaerotheca Myclobutanil may be used to control powdery mildew. C. phytoptophylla and an Eriophyid Mite jessoensis, C. sinensis, and C. laevigata are reported to be resistant.

Cercis (Redbud) Canker: Botryosphaeria ribis Prune and destroy affected branches during dry weather. Avoid injuries by humans and insects.

Chaenomeles (Quince) Fire Blight: Erwinia amylovora Destroy nearby neglected pear, apple, and quince. Prune out infected parts when plants are dry, making each cut inches below areas of visible discoloration. Disinfect pruning tools between each cut.

Leaf Spot: Entomosporium Destroy fallen leaves. Apply Thiophanate-Methyl, Chlorothalonil, Spectro 90 WDG, Myclobutanil, or Mancozeb.

Chamaecyparis (Cedar) Blight: Phomopsis juniperovora See Juniperus. The following cultivars, all of C. pisifera are reported to be resistant: ‘Filifera,’ ‘Aureovariegata,’ ‘Plumosa Argentea,’ ‘Plumosa Lutescens,’ and ‘Squarrosa Sulfurea’.

Cornus (Dogwood) Crown Canker: Phytophthora Avoid mechanical injuries, especially to the lower stems and cactorum roots. Control borers as needed. Plants with cankers encircling more than half of the stem should be removed and the area should not be replanted with dogwood. For plants with smaller cankers, apply Metalaxyl-m.

Flower and Leaf Blight: Botrytis Disease is serious only in wet years. If wet weather occurs cinerea during bloom and the plant or field has a history of disease, spray once with Chlorothalonil, Thiophanate-Methyl, Spectro 90 WDG, Zyban, Junction, Iprodione, Copper Sulfate Pentahydrate, Potassium Bicarbonate, or Mancozeb.

Anthracnose: Discula destructiva Destroy fallen leaves and prune out diseased twigs. Keep plants well watered. Spray with Chlorothalonil, Propiconazole, Manhandle, Mancozeb, 4 Flowable, Mancozeb DG, Dithane 75 F.

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Plant and Disease Disease Prevention and Control

Cornus (Continued) Powdery Mildew: Microsphaera, Powdery mildew on dogwood has become increasingly severe Phyllactinia in recent years. Mildew infections may be most prominent during the latter half of the growing season. Apply Copper Sulfate Pentahydrate, Myclobutanil, Triadimefon, Potassium Bicarbonate, Kresoxim-Methyl, Manhandle, or Spectro 90 WDG when mildew becomes evident, and make additional applications as required.

Spot Anthracnose: Elsinoe corni If disease was severe the previous year, spray with Copper Hydroxide,, Mancozeb, Junction, Elemental Copper, Myclobutanil, Maneb, Chlorothalonil, Manhandle, or Azoxystrobin at monthly intervals, beginning when flower buds have opened to the cup stage and continuing until new flower buds have formed, or apply Potassium Bicarbonate.

Twig Blights and Cankers: Prune diseased branches back to sound wood and destroy Myxosporium everhartii them. Water during dry periods.

Corylus (Filbert, Hazelnut) Eastern Filbert Blight: Prune infected branches as they appear, and burn or bury Anisogramma anomala them. Remove heavily infected plants. Do not plant Corylus in sites with a history of the disease. Chemical control may not be practical in all landscape situations. Where needed, apply Kocide 2000 T/N/O.

Cotoneaster (Cotoneaster) Fire Blight: Erwinia amylovora Destroy nearby neglected pear, apple, and quince. Prune out infected parts when plants are dry, making each cut several inches below areas of visible discoloration. Disinfect pruning tools between each cut. Where necessary, apply Copper Sulfate Pentahydrate.

Crataegus (Hawthorn) Fire Blight: Erwinia amylovora Use sanitation for fire blight as on cotoneaster. Avoid heavy fertilization. Apply Fosetyl-Al, Copper Hydroxide, or Phosphorous Acid at 7- to 10-day intervals beginning when flower buds swell and continuing until bloom period ends.

Leaf Spot: Entomosporium Destroy fallen leaves. Spray with Mancozeb, Manhandle, Myclobutanil, Maneb, Twosome, Chlorothalonil, or Spectro 90 WDG as leaf buds open and twice thereafter at 10- to 14- day intervals. May need additional applications in rainy years. Do not plant highly susceptible English hawthorns. C. crus- galli is resistant.

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Plant and Disease Disease Prevention and Control

Crataegus (Continued) Rusts: Gymnosporangium Eliminate nearby red cedar and common juniper where possible. Spray with Chlorothalonil, Twosome, Spectro 90 WDG, Mancozeb, Zyban, Triadimefon, Propiconazole, Maneb, Manhandle, Kresoxim-Methyl, or Myclobutanil when orange rust masses appear on juniper around mid-May and three times thereafter at 7- to 14-day intervals. C. crus-galli, C. laevigata ‘Autumn Glory,’ C. phaenopyrum, C. Pruninosa, and C. Viridis ‘Winter King’ are said to be resistant to G. globosum.

Scab: Venturia inaequalis Destroy fallen leaves. Spray with Mancozeb, Maneb, Myclobutanil, Thiophanate-Methyl, Trifloxystrobin, Kresoxim -Methyl, or Spectro 90 WDG at pink bud and at petal fall, plus two more applications at 7- to 14-day intervals.

Fraxinus (Ash) Anthracnose: Discula Destroy fallen leaves. If disease was severe the previous year and spring conditions are wet, spray with Mancozeb, Junction, Maneb, Thiophanate-Methyl, Manhandle, or Spectro 90 WDG at budbreak and twice thereafter at 10- to 14-day intervals.

Yellows: A. phytoplasma Foliage discoloration, growth reduction, and crown death are more severe on water-stressed trees. Improve root zone health via irrigation when drought threatens.

Hedera (English Ivy) Leafspot: Xanthomonas campestris Remove and destroy affected leaves in autumn. Apply Copper Hydroxide, Fosetyl-Al, Phosphorous Acid, or Camelot as symptoms appear during the growing season. Copper Hydroxide is toxic to some Hedera. If in doubt, treat only a few plants and wait two days. ‘Gold Dust’ is resistant. ‘Brokamp’ and ‘Hahn Variegated’ are highly susceptible.

Juglans (Walnut, Butternut) Bacterial Blight: Xanthomonas Prune and destroy infected shoots, disinfecting tools between juglandis cuts. Apply Junction at pre-bloom and early nutlet stages.

Anthracnose: Gnomonia leptostyla Destroy fallen leaves. Spray with Maneb, Mancozeb, Junction, Propiconazole, Thiophanate-Methyl, Chlorothalonil, Manhandle or Spectro 90 WDG three times at two-week intervals beginning at budbreak.

Juniperus (Juniper, Red Cedar) Rust: Gymnosporangium Do not plant near hawthorn, flowering crab, quince, or similar plants. Remove galls from plants in spring where practical. Spray severely affected plants with Triadimefon,

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Plant and Disease Disease Prevention and Control

Juniperus (Continued) Myclobutanil, Mancozeb, Zyban, Azoxystrobin, or Junction two times at three-week intervals beginning in early August. Use disease-resistant selections for new plantings.

Blight: Phomopsis juniperovora Prune and destroy infected shoots where practical. Avoid overhead irrigation. Rogue and destroy infected plants in young plantings. Spray with Maneb, Mancozeb, Propiconazole, Azoxystrobin, Fungisol, Thiophanate-Methyl, Manhandle, Zyban, or Junction at two-week intervals throughout the growing season.

Blight: Kabatina juniperi Spray with Thiophanate-Methyl, Protect T/O, or Fungisol. In sites with a history of this disease, plant resistant selections.

Ligustrum (Privet) Anthracnose: Glomerella cingulata Prune and destroy infected branches during dry weather. Spray with Chlorothalonil, Mancozeb, Fungo 50 WSB, Spectro 90 WDG, or Junction weekly as long as disease is active. Amur privet (Ligustrum amurense), Ibota privet (L. ibota) and Regal privet (L. obtusifolium var. regalianum) are reported to be resistant.

Lonicera (Honeysuckle) Leaf Blight: Insolibasidium deformans Remove and destroy fallen leaves. Spray with Mancozeb, Junction, Manhandle or Maneb at 10-day intervals beginning in late May and continuing until late June.

Malus (Apples, Flowering Crab) Powdery Mildew: Podosphaera Apply Propiconazole, Triadimefon, Myclobutanil leucotricha Thiophanate-Methyl, Zyban, Spectro 90 WDG, Trifloxystrobin, Kresoxim-Methyl, Stylet Oil, Twosome or Potassium Bicarbonate at two-week interval when mildew first appears on twigs or foliage

Fire Blight: Erwinia amylovora Avoid over-fertilization, especially heavy spring applications of nitrogen. Cut out cankers and blighted branches in mid- January when tree is dry, making cuts at least one foot below the visible limits of infection. Disinfect tools between cuts. Remove worthless pear, apple, quince, and similar plants from the vicinity. Where disease has just begun to appear, apply Copper Sulfate Pentahydrate or Copper Hydroxide.

Rust: Gymnosporangium Eliminate nearby red cedar and common juniper to whatever extent practical. Spray with Myclobutanil, Maneb,

37.3-16 1106

Plant and Disease Disease Prevention and Control

Malus (Continued) Triadimefon, Chlorothalonil, Trifloxystrobin, Manhandle, Propiconazole, Twosome, Spectro 90 WDG, Mancozeb, or Zyban. Make three applications at 7- to 14-day intervals beginning when orange rust masses develop on junipers or around mid-may.

Scab: Venturia inaequalis Spray Propiconazole, Myclobutanil, Copper Sulfate Pentahydrate, Maneb, Mancozeb, Trifloxystrobin, Thiophanate-Methyl, Zyban WSP, Chlorothalonil, Kresoxim- Methyl, Manhandle, Twosome, or Spectro 90 WDG. Azoxystrobin may be used for tolerant crabapple species.

The following crabapples have been evaluated through a program of yearly assessment for disease incidence at sites throughout the eastern half of the United States: ‘Adams’, ‘Jackii’, ‘Baskatong’, ‘Centurion’, ‘Dolgo’, ‘Donald Wyman’, ‘Harvest Gold’, ‘Henry Kohankie’, ‘Indian Summer’, ‘Liset’, ‘Ormiston Roy’, ‘Prof Springer’, ‘Red Jewel’, ‘Robinson’, ‘Sentinel’, and ‘Sugartime’

Pachysandra (Pachysandra, Spurge) Blight: Volutella pachysandricola Plants grown in full sun are most likely to become diseased. Those in full shade usually remain healthy. Where plants are already established and disease has become intolerable, rouge and destroy diseased plants. Spray with Copper Hydroxide, Elemental Copper, Camelot, Manhandle, Maneb, Mancozeb, Zyban, Junction, Chlorothalonil, Twosome, or Spectro 90 WDG two or three times at 10-day intervals beginning when new growth starts.

Parthenocissus (Boston Ivy, Virginia Creeper, Woodbine) Leaf Spot: Guignardia bidwellii Hand pick and destroy infected leaves where possible. Sprays are seldom necessary.

Picea (Spruce) Canker: Leucostoma kunzei Keep trees lightly fertilized and watered and avoid all wounds. Remove and destroy all diseased parts, disinfecting tools between cuts. Do not prune in wet weather. Fungisol micro- injections may be used in landscape situations.

Needlecast: Rhizosphaera kalkhoffii This disease is rarely severe enough to warrant control measures. In ‘Christmas tree plantations where damage has become intolerable, use Elemental Copper, Protect T/O, Chlorothalonil, Twosome, Spectro 90 WDG, or Copper Hydroxide.

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Plant and Disease Disease Prevention and Control

Picea (Continued) Twig Blight: Sirococcus Rouge and destroy heavily infected trees. Spray Chlorothalonil, Twosome, Spectro 90 WDG, or Azoxystrobin before new shoot growth is ½ inch long and spray twice thereafter at three- to four-week intervals.

Weir’s Cushion Rust: Chrysomyxa Fungus causes bright orange blisters on one-year-old needles weirii in the spring and premature shedding of those needles. Apply Chlorothalonil when budbreak is 10 percent complete, and make two more applications at 7- to 10-day intervals.

Blister Rust: Cronartium ribicola To whatever extent possible, eradicate wild currants and gooseberries within 500 feet and maintain 200 feet separation between white pines and cultivated red currants. To eliminate cankers on pine, prune off cankered lateral branches or excise stem cankers by removing bark at least four inches above and below and two inches on either side of discolored bark.

Gall Rust: Endocronartium Cull seedlings with stem swellings, and cut off branch galls harknessii and rouge heavily galled trees before May 1. Apply Mancozeb, Maneb, or Manhandle three times at two-week intervals when yellow pustules begin to erupt through bark on galls.

Needlecast: Lophodermium Spray heavily infected trees with Maneb, Mancozeb, Junction, Chlorothalonil, Twosome, or Spectro 90 WDG monthly from June to October 1, or apply Azoxystrobin or Manhandle per label directions.

Needlecast: Cyclaneusma minus This common disease causes two- and three-year-old needles to turn yellow to light brown in late summer and fall. It rarely, if ever, threatens tree health and usually does not warrant control efforts. Where symptoms have become intolerable, spray trees with Mancozeb, Junction, Chlorothalonil, Twosome, or Spectro 90 WDG once at budbreak and thereafter at six- to eight-week intervals until spore dispersal ceases in late fall.

Needlecast: Ploioderma lethale Spray with Chlorothalonil once when new shoots are one-half to two inches long or when needles begin to emerge from the fascicles and twice again at three- to four-week intervals or until conditions no longer favor disease.

Needle Blight: Mycosphaerella pini = Spray with Elemental Copper, Camelot, Protect T/O, or Dothistroma septospora Junction once at budbreak and twice again at 10- to 14-day intervals.

37.3-18 1106

Plant and Disease Disease Prevention and Control

Picea (Continued) Needle Rust: Coleosporium Goldenrod and aster plants are alternate hosts for the rust. asterum Control these weeds annually before August. Where disease is severe, treat with Triadimefon.

Sweetfern Rust: Cronartium Sweet fern and sweet gale are alternate hosts for the rust. comptoniae Control these plants before August. Cull seedlings with stem swellings or if showing rust pustules. Where disease is severe, treat with Triadimefon.

Twig Blight: Sphaeropsis sapinea Prune and destroy affected cones, twigs, and branches during dry weather in autumn. Spray with Thiophanate-Methyl plus a spreader-sticker, or apply Spectro 90 WDG, Camelot, Protect T/O, Junction, or Propiconazole just before budbreak and make two more applications at 10-day intervals, or apply Azoxystrobin.

Populus (Poplar, Aspen, Cottonwood) Cankers: Cytospora chrysosperma, For Cytospora canker, keep trees well watered and fertilized. Cryptodiaporthe populea Avoid wounding. Prune out and destroy infected branches during dry weather. For Cryptodiaporthe canker, destroy severely affected trees. Do not plant Lombardy poplars. The Japan poplar, Populus maximowiczii, is said to have some resistance to cankers.

Leafspot: Marssonina brunnea Rake and destroy infected leaves in the fall. Where disease is persistent, make three applications of Chlorothalonil, Mancozeb, Twosome, Spectro 90 WDG, Cleary’s 3336WP or 3336F, or Junction at 10- to 14-day intervals beginning at budbreak or apply Azoxystrobin.

Shoot Blight/Stem Canker: Rouge and destroy severely diseased trees. Prune cankered Mycosphaerella branches, disinfecting tools between cuts. Spray salvageable trees with Chlorothalonil, Mancozeb, Spectro 90 WDG, or Cleary’s 3336WP or 3336F three times at 10- to 14-day intervals beginning at budbreak. Cultivar ‘Assiniboine’ is resistant.

Prunus (Cherry, Flowering Cherry, Peach, Plum) Black Knot: Dibotryon morbosum Prune knotted twigs to whatever extent practical, and excise knots on large limbs before April 1. Destroy pruned material.

Leaf Curl: Taphrina deformans Apply Spectro 90 WDG, Junction, or Pentathlon DF, or LF in late spring before budbreak.

37.3-19 1106

Plant and Disease Disease Prevention and Control

Prunus (Continued) Crown Gall: Agrobacterium Seventy-seven genera of woody plants are susceptible to tumefaciens crown gall. Plants become infected when planted in infected soil through wounds from pruning, cultivating and grafting. Few if any control measures are effective.

Leaf Spot: Blumeriella jaapii Spray with Propiconazole, Protect T/O, Junction, Myclobutanil, Spectro 90 WDG, or Cleary’s 3336WP, or 3336F, or Kresoxim-Methyl on labeled species or varieties, at petal fall plus two more applications at two-week intervals.

Shoot Blight (Crown Rot): Prune and destroy infected twigs if practical. Spray with Monilinia fructicola Propiconazole, Mancozeb, Junction, Chlorothalonil, Spectro 90 WDG, or Cleary’s 3336WP or 3336F as blossoms open and again 10 days later.

Pseudotsuga (Douglas Fir) Needlecast: Rhabdocline Plant on slopes and control weeds to promote air drainage and dry conditions among lower branches. If disease develops, rouge severely infected trees, and prune lower branches before May 1. Apply Chlorothalonil, Spectro 90 WDG, or Twosome before new growth is one-half inch long, and make additional applications at three- to four-week intervals until July 1.

Swiss Needlecast: Phaeocryptopus Time treatments as for Rhabdocline. Use Maneb, Mancozeb, gaumannii Chlorothalonil, Twosome, Manhandle, or Spectro 90 WDG.

Pyrus (Pear) Fire Blight: Erwinia amylovora Prune out diseased parts when plants are dry, disinfecting tools between cuts. Make cuts several inches below visible limits of infection. Remove worthless pear, apple, and quince from the vicinity. The Bradford pear (Pyrus calleryana cv. ‘Bradford’) is reported to be tolerant. P. beautifolia ‘Dancer’ is resistant. Where severe, treat with Fosetyl-Al, Camelot, Copper Hydroxide, Junction, Phosphorous Acid, or Copper Sulfate Pentahydrate.

Scab: Venturia pirina Spray with Thiophanate-Methyl, Myclobutanil, Mancozeb, Kresoxim-Methyl (not on ‘Olympic’).

Quercus (Oak) Anthracnose: Apiognomonia Destroy fallen leaves in autumn. Spray with Protect T/O, Elemental Copper, Camelot, Thiophanate-Methyl, or Spectro 90 WDG once before budbreak, once at budbreak, and once when leaves are half of full size, or use Fungisol for injection in the spring.

37.3-20 1106

Plant and Disease Disease Prevention and Control

Quercus (Continued) Leaf Spot: Tubakia dryina This disease develops late in the growing season and rarely threatens tree health. Where management must be undertaken, spray with Elemental Copper, Camelot, Propiconazole, or Kocide 2000 T/N/O once at budbreak and twice thereafter at 10- to 14-day intervals.

Leaf Blister: Taphrina caerulescens This disease rarely is severe enough to affect host health or appearance. Where it has become so, spray once in spring before bud swell with Mancozeb, Maneb, Chlorothalonil, Twosome, Manhandle, or Spectro 90 WDG.

Shoestring Root Rot: Armillaria This disease most frequently affects trees weakened by defoliation or other factors. Restore tree vigor via watering and fertilization and control of defoliators.

Rhododendron (Azalea, Rhododendron) Azalea Gall: Exobasidium vaccinii Pick and destroy galls. Spray with Elemental Copper, Triadimefon, Camelot, Junction, or Spectro 90 WDG three times at 10- to 14-day intervals beginning at budbreak.

Canker and Dieback: Botryosphaeria Prune and destroy infected parts, disinfecting tools carefully ribis between cuts. Cultivars reported to be resistant include ‘Boursalt’, ‘Chionoides White’, ‘Cuningham’s White’, ‘English Roseum’, ‘LeBar’s Red’, ‘Roseum 2’, ‘Sweet Simplicity’, and ‘Wissahickon’. Where needed, treat with Protect T/O.

Shoot Blight: Phytophthora For existing plantings, prune and destroy infected twigs. As new leaves appear, spray with Mancozeb, Chlorothalonil, Twosome, Maneb, Camelot, Manhandle, or Azoxystrobin, making three applications 7- to 10-days apart, or apply a drench with Metalaxyl-m or Phosphorous Acid.

Flower Blight: Ovulinia azaleae If disease was severe the previous year, spray twice with Triadimefon, Chlorothalonil, Thiophanate-Methyl, Mancozeb, Myclobutanil, Propiconazole, Zyban, Junction, Spectro 90 WDG, Manhandle, or Twosome.

Root Rot and Wilt: Phytophthora Several other Rhododendron problems have symptoms similar cinnamomi to those caused by Phytophthora. Be sure of correct diagnosis. Avoid planting in heavy or frequently saturated soils. Rouge and destroy infected plants, including roots, when symptoms appear. Drench soil with Metalaxyl-m, Etridiazole, Banrot, Propamocarb, Hydrochloride, Phosphorous Acid, or Fosetyl- Al before planting new plants in a site with a history of disease.

37.3-21 1106

Plant and Disease Disease Prevention and Control

Rhododendron (Continued) Powdery Mildew: Microsphaera Spray with Triadimefon, Thiophanate-Methyl Ultrafine Oil, Camelot, Spectro 90 WDG, Azoxystrobin, Manhandle, Myclobutanil or Potassium Bicarbonate when disease incidence becomes intolerable.

Rosa (Rose) Flower Blight: Botrytis Disease is most severe in years with unusually high rainfall or in sites where overhead irrigation is excessive. Remove and destroy blighted flowers and spray with Mancozeb, Thiophanate-Methyl, Chlorothalonil, Iprodione, Copper Sulfate, Pentahydrate, Trifloxystrobin, Zyban, Junction, Spectro 90 WDG, or Twosome, or apply potassium bicarbonate.

Blackspot: Diplocarpon rosae Remove and destroy cankered canes. Spray at 7- to 14-day intervals with Maneb, Propiconazole, Myclobutanil, Copper Sulfate Pentahydrate, Chlorothalonil, Line Sulfur, Mancozeb, Thiophanate-Methyl, Copper Hydroxide, Fenarimol, Neem Oil, Manhandle, Kresoxim-Methyl, Zyban, Junction, Trifloxystrobin, Spectro 90 WDG, or Twosome beginning as leaves expand. Or apply Camelot for suppression.

Crown Gall: Agrobacterium Seventy-seven genera of woody plants are susceptible to tumefaciens crown gall. Plants become infected when planted in infected soil through wounds from pruning, cultivating and grafting. Few, if any, control measures are effective.

Powdery Mildew: Sphaerotheca Spray Lime Sulfur, Triadimefon, Myclobutanil, pannosa Propiconazole, Copper Hydroxide, Elemental Copper, Thiophanate-Methyl, Zyban, Junction, Spectro 90 WDG, Trifloxystrobin, Twosome, Azoxystrobin, Manhandle, Kresoxim-Methyl, Neem Oil, Horticultural Oil, or Potassium Bicarbonate when mildew appears on leaf surface, and repeat applications at 10- to 14-day intervals as needed, or use Camelot for suppression.

Rust: Phragmidium Spray with Protect T/O, Junction, Myclobutanil, Propiconazole, Azoxystrobin, Trifloxystrobin, Manhandle, or Kresoxim-Methyl when orange rust pustules are first seen on underside of leaves. Repeat as needed.

Salix (Willow) Leaf Rust: Melampsora epitea Spray foliage with Triadimefon or Mancozeb once at budbreak and twice thereafter at two-week intervals.

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Plant and Disease Disease Prevention and Control

Salix (Continued) Blight, Black Canker: Venturia Prune heavily to remove diseased parts or spray with Junction saliciperda, Glomerella miyabeana at 7- to 10-day intervals when disease first appears. Salix babylonica (Weeping Willow) and S. pentandra (Laurel Willow) are somewhat resistant.

Canker: Cytospora chrysosperma Keep trees well watered. Avoid wounding. Prune out and destroy infected branches during dry weather.

Sorbus (Mountain Ash) Fire Blight: Erwinia amylovora Prune out diseased parts when plants are dry, disinfecting tools between cuts. Make cuts several inches below visible limits of infection. Remove worthless pear, apple, and quince from the vicinity. Where disease has just begun to appear, apply Copper Sulfate Pentahydrate or Copper Hydroxide.

Cankers: Cytospora, Fusicoccum Keep trees well watered. Avoid wounding. Prune out and destroy infected branches during dry weather.

Scab: Venturia inaequalis Apply Protect T/O, Junction, Copper Sulfate Pentahydrate, or Cleary’s 3336 WP or 3336F at budbreak and repeat at 7- to 21-day intervals during leaf expansion while conditions for disease development exist.

Syringa Lilac) Bacterial Blight: Pseudomonas Prune to prevent dense growth. Cut out and destroy infected syringae shoots as soon as symptoms appear, disinfecting tools between cuts. When disease incidence has become intolerable, spray once during dormancy with Elemental Copper, or apply Copper Sulfate Pentahydrate or Junction.

Powdery Mildew: Microsphaera alni Spray Lime Sulfur, Cleary’s 3336 WP or 3336F, Zyban, Spectro 90 WDG, Triadimefon, Copper Sulfate Pentahydrate, Myclobutanil, Kresoxim-Methyl, or Ultrafine Oil when Mildew appears on leaf surface and repeat applications at 10- to 14-day intervals as needed.

Thuja (Arborvitae) Leaf Blight: Cercospora Destroy heavily infected plants. Spray with Maneb, Mancozeb, Copper Hydroxide, Manhandle or Junction three times at two-week intervals beginning at budbreak, or apply Azoxystrobin.

Tsuga (Hemlock) Canker: Leucostoma, Cytospora Do not plant hemlock on neutral or alkaline sites or where Valsa plants will be subject to water stress or salt exposure. Water

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Plant and Disease Disease Prevention and Control

Tsuga (Continued) established plants during dry periods and keep them lightly fertilized. Prune out dead and dying branches.

Rust: Melampsora Apply Triadimefon or Mancozeb (Pentathlon DF or LF) once when buds break and twice thereafter at 7- to 14-day intervals. Where disease has been severe, do not plant hemlock.

Ulmus (Elm) Black Leaf Spot: Stegophora ulmea Premature defoliation by this disease does not threaten tree health. Apply Maneb, Mancozeb, Manhandle, or Junction three times at two-week intervals beginning at budbreak if the effect of the disease on a particular tree has become intolerable.

Dutch Elm Disease (DED): Where both diseases occur, chances of preserving a Ophiostoma novo-ulmi, susceptible elm are poor. Proven recommendations for control Elm Yellows (EY): A phytoplasma of Elm Yellows are not available. For Dutch Elm Disease, the following procedures should be implemented:

1. Eliminate all potential beetle-breeding elm material within 700 feet of trees to be protected. Sanitation is useful even where zones extending several hundred feet from valuable elms cannot be established.

2. Make dormant applications of Chlorpyrifos for control of beetles.

3. Trunks can be injected with Thiabendazole Hypophosphite. Use Alamo, Fungisol, or Copper Sulfate Pentahydrate for protection or therapy. Good success has been obtained with both macro- and micro-injection equipment. Combine eradicative pruning (step 4) with therapeutic treatments as soon as symptoms are seen.

4. Prune out DED-infected branches, making sure the pruning cut shows no evidence of vascular discoloration. Pruning alone is effective in a minority of cases if symptoms are detected while confined to a small branch and a large branch bearing the small one is immediately removed. Chances for recovery are much better if fungicide injection is also used.

Viburnum (Viburnum) Downy mildew: Plasmopara viburni Spray with Maneb, Mancozeb, Manhandle, Zyban, or Junction at two-week intervals between April 1 and June 15.

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Plant and Disease Disease Prevention and Control

Vinca Periwinkle) Stem Canker Leaf Spot and Botrytis Rouge and destroy affected stems. Thin stand to promote Blight: Botrytis cinerea better air circulation. Then, if disease has been severe, treat plants with a soaking spray of Mancozeb, Thiophanate- Methyl, Zyban, Copper Sulfate Pentahydrate, or Iprodione, or apply Potassium Bicarbonate.

Stem Blight: Phomopsis Prune and destroy affected shoots. Spray with Copper Hydroxide or Mancozeb as symptoms become apparent.

1Pesticides recommended in the table above may not be registered for use in both nurseries and landscapes. Ensure that the product is labeled for the pests, host, and site on which it is to be applied. See product labels for recommended rates of application for each pesticide. Trade names have been used where two active ingredients are combined into one product, and where only one or two labels within a larger list of products are actually registered for that peat and host. No endorsements are to be implied.

2Verticillium Wilt A fungus called Verticillium dahliae causes Verticillium Wilt, which occurs in many genera of woody plants. Maples comprise the most important group of wood plants highly susceptible Verticillium Wilt. The pathogen is soil borne and can persist for many years in the soil without host plants. The disease is common in nurseries that have been established on land formerly planted with fruit, bramble, vegetable, or field crops, many of which are also susceptible. If Verticillium Wilt has occurred in previous crops on a particular site, susceptible plants must not be planted on this infected site.

There is no guaranteed method to rid soil of Verticillium dahliae, once the soil has been contaminated. Soil fumigation may help, but it is probably a bad investment if done for the sole purpose of controlling Verticillium dahliae. Since the disease cannot be controlled, it must be prevented from getting started by planting clean stock on sites where previous occurrence of the disease has not been observed. For susceptible species and varieties, obtain guarantees from suppliers that the stock being purchased is Verticillium-free.

If a tree or shrub that is already established in a landscape becomes infected with Verticillium, it may still live and be a serviceable plant for many years. Trim symptomatic parts from the plant, disinfecting tools between cuts. Be sure the plant has adequate water and nutrition because Verticillium spreads more quickly in plants growing in less than optimal sites If an established tree or shrub must be removed because it is dying from Verticillium Wilt and a replacement is desired, use a resistant plant. Yews and conifers are not affected by Verticillium Wilt. Broadleaf tree and shrub genera with some resistance include, but are not limited. to the following: Betula, Cornus, Gleditsia, Quercus, Sorbus, Carpinus, Ginkgo, Malus and Salix. Although maples are generally considered to be highly susceptible to Verticillium Wilt, red and sugar maples appear to be much more resistant than Norway maples.

A REMINDER The information given in this publication is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Minnesota Nursery and Landscape Association, the Minnesota Extension Service or Cornell University is implied. A complete list of brand names is not included and inclusion or exclusion does not constitute any claim or endorsement about product effectiveness. The reader is reminded that it is illegal to use any pesticide for any purpose or on any plant, which is not specifically stated on the label. For the safety of individuals, the environment, and the continued use of valuable products, it is critical to understand the requirements, the procedures and the products. Read, understand and follow the label. It’s the law!

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Table 5. Common chemical names and trade names of fungicides for use on turf. From: Klass, C. and K.L. Snover-Clift. 2005. Pest Management and the Home Part II. 2005- 2006 Pesticide Guidelines. Cornell University Cooperative Extension.

Common Chemical Name Trade Name EPA Registration Number Azoxystrobin Heritage 100-1093

Captan Bonide Captan 66330-27-4 Captan Garden Spray 66330-27 Hi-Yield Captan 66330-27-7401

Chitosan Elexa-4 70464-3

Chloroneb Teremec SP 2217-692

Chlorothalonil Bonide Fung-onil MPF Concentrate 60063-9-4 Lesco Manicure T/O Flowable 60063-9-10404 Ferti-lome Broad-spectrum Liquid Fungicide 7401-65

Flutalonil + Thiophanate- Sysstar WDG 48234-18 Methyl

Fosetyl-Al Monterey Aliette 264-556-54705

Mancozeb Protect DF 1001-77 Protect T/O 1001-65

Maneb Gordon’s Maneb Tomato and Vegetable Fungicide 2217-546

Metalaxyl-m Subdue GR 100-794 (Mefenoxam) Subdue MAXX 100-796

Myclobutanil Spectrascide Immunox MPF 9688-123-8845 Anderson’s Golden Eagle 9198-207

Propiconazole Bonide Infuse Systemic Disease Control 100-773-4 Ferti-Lome Liquid Systemic Fungicide 100-773-7401

Quintozene (PCNB) Hi-Yield T&O Fungicide Contains 10% Terrachlor 5481-444-7401 Turfcide 400 400-454

Thiophanate-Methyl Cleary’s 3336F 1001-69

Thiram Spotrete 75 WDG 1001-60

Triadimefon Bonide Lawn Fungicide with Bayleton 4-342

Trichoderma harzianum Turfshield Granules 68539-3

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Table 6. Turf diseases and disease management options. From: Klass, C. and K.L. Snover-Clift. 2005. Pest Management and the Home Part II. 2005- 2006 Pesticide Guidelines. Cornell University Cooperative Extension.

Turf Disease Disease Pesticides and Management

Anthracnose Apply Sysstar WDG, Chitosan, Propiconazole, Triadimefon, Cleary’s 3336F, Heritage or Anderson’s Golden Eagle.

Brown Patch (Rhizoctonia Blight) When the disease occurs, apply Mancozeb, Sysstar WDG, Maneb, Myclobutanil, Captan, Thiophanate-Methyl, Thiram, Propiconazole, Chlorothalonil, Triadimefon, Chloroneb, Quintozene or Heritage.

Dollar Spot Apply Mancozeb, Thiophanate-Methyl, Thiram, Propiconazole, Chlorothalonil, Triadimefon, Quintozene, or Anderson’s Golden Eagle.

Fairy Rings and Toadstools Mask symptoms with good fertility, watering, and mowing programs. Rake down or pick and discard the mushrooms. May apply Sysstar WDG, Maneb, Heritage or Spectracide Immunox MPF where other practices are unsuccessful. Follow label directions.

Fungal Leaf Spots and Blights Avoid systemic fungicides. Apply Mancozeb, Captan, Chitosan, (Drechslera, Bipolaris) Spectracide Immunox MPF or Heritage.

Gray Snow Mold (Typhula) In repeatedly severe cases, apply Sysstar WDG, Thiram, Chlorothalonil, Triadimefon, Chloroneb, Quintozene or Heritage before permanent snow cover and during midwinter thaws.

Necrotic Ringspot and Summer Where the disease has occurred in previous years, apply Myclobutanil, Patch (Formally Fusarium Blight Thiophanate-Methyl, Triadimefon, or Heritage beginning in early to mid- Syndrome) June with a second application two to three weeks later.

Pink Snow Mold (Gerlachia In repeatedly severe cases, apply Sysstar WDG, Mancozeb, Thiophanate- Patch) Methyl, Triadimefon, Quintozene or Heritage.

Powdery Mildew When the disease occurs, apply Mancozeb, Fosetyl-Al, Metalaxyl-m, Chloroneb or Heritage.

Pythium Root and Crown Rot In severe cases apply Fosetyl-Al, Metalaxyl-m or Heritage. Use the biological control agent Trichoderma harzianum, sold as Turfshield, to help prevent outbreaks.

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Table 6 (Continued). Turf diseases and disease management options. From: Klass, C. and K.L. Snover-Clift. 2005. Pest Management and the Home Part II. 2005- 2006 Pesticide Guidelines. Cornell University Cooperative Extension.

Red Thread Red Thread typically does not damage turf. However, if control is deemed necessary, apply Triadimefon in spring and fall, or apply Sysstar WDG, Mancozeb, Thiophanate-Methyl, Propiconazole, Bonide Fung-onil Concentrate, Spectracide Immunox MPF, or Heritage according to label directions.

Rust Only where infection is extensive and severe, apply Chlorothalonil, Mancozeb, Triadimefon, Myclobutanil, Thiophanate-Methyl or Propiconazole.

Smuts In late fall when grass stops growing or in early spring before grass starts growing, apply Triadimefon or Thiophanate-Methyl.

A REMINDER

The information given in this publication is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Minnesota Nursery and Landscape Association, the Minnesota Extension Service or Cornell University is implied. A complete list of brand names is not included and inclusion or exclusion does not constitute any claim or endorsement about product effectiveness. The reader is reminded that it is illegal to use any pesticide for any purpose or on any plant, which is not specifically stated on the label. For the safety of individuals, the environment, and the continued use of valuable products, it is critical to understand the requirements, the procedures and the products. Read, understand and follow the label. It’s the law!

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