Sweet Corn Weed Control Evaluations on Mineral and Organic Soils
Proc. Fla. State Hort. Soc. 105:326-330. 1992.
SWEET CORN WEED CONTROL EVALUATIONS ON MINERAL AND ORGANIC SOILS
G. S. Crnko with atrazine, was the major herbicide used in sweet corn Seminole County Cooperative Extension Service grown in organic soils. Metolachlor, a related acetanilide IFAS, University of Florida herbicide, contains labeling restrictions for use on organic Sanford, FL 32773 soil (Stall, 1991). Pendimethalin has a label for use on sweet corn applied W. M. Stall preemergence or early postemergence in several states. Horticultural Sciences Department Sweet corn has been damaged when pendimethalin was IFAS, University of Florida applied preemergence in Florida. In initial studies pen Gainesville, FL 32611 dimethalin applied to sweet corn postemergence at the spike growth stage did not injure plants grown on mineral J. M. White soils. Central Florida Research and Education Center With the availability of limited preemergence her IFAS, University of Florida bicides, the use of postemergence herbicides may be in Sanford, FL 32771 creasing. Cultivation is used to control weeds between rows. However, grass and broadleaf weeds can become a Additionalindex words. Sweet corn, Zea mays var. rugosa, her great problem in the plant row. Sethoxydim and linuron bicides, metolachlor, pendimethalin, atrazine, bromoxynil, are both labeled for use as a directed spray. Tank-mixes pyridate, sethoxydim, linuron. of these materials had not been tested for control ofboth broadleaf weeds and grasses. Abstract Several herbicides were evaluated on a mineral soil Bromoxynil has a label for control of emerged broad in Gainesville and on an organic soil in Ze 11 wood, FL in 1991 leaf weeds on field corn and popcorn,but not on sweet and 1992 for weed control in sweet corn [Zea mays L. var. corn. The use of two new sulfonylurea herbicides, nicosul- rugosa Bonaf .)• Metolachlor and pendimethalin were applied fuion and primisulfuron is not recommended in sweet at several rates alone and tank-mixed with atrazine for corn due to the differential responses of sweet corn cul- preemergence control of weeds and evaluated for crop safety. tivars to these herbicides. Phytotoxicity with these two her Bromoxynil was applied alone and bromoxynil and pyridate bicides may also be enhanced when organophosphate in were tank-mixed with atrazine applied post over-the-top and secticides are used (Monks et al., 1992; Stall and Bewick, were evaluated for broadleaf weed control and crop safety. 1992). Sethoxydim, linuron and tank mixes of sethoxydim-linuron, The purpose of these studies was to evaluate potential and sethoxydim-atrazine were applied post-directed and herbicides for weed control and phytotoxicity on mineral were evaluated for crop safety and weed control. Metolachor and organic soils in Florida. and pendimethalin treatments did not cause crop toxicity and controlled grass weeds. Several broadleaf weeds were not effectively controlled season long, especially on the organic soils. Bromoxynil and pyridate applications effectively con Materials and Methods trolled the broadleaf weeds found in these fields with no Experiments on mineral soils were conducted at the damage to sweet corn. Sethoxydim, linuron and the tank Horticultural Unit, Gainesville, Florida during the Spring mixes applied post-directed did not provide any crop damage, of 1991 and 1992. Plots for both years were on 4 foot while controlling very large weeds. center beds in a randomized complete block design on a Pomona sand with 1.2 and 2.2 percent organic matter and Florida is the leading state in the nation in fresh market a pH of 6.5 and 6.8, respectively. sweet corn production. In the 1990-91 crop season, 51,700 Sweet corn 'SS-8701' and 'Dazzle' were planted 11 Apr. acres of sweet corn were planted in Florida. This is down 1991 and 6 Apr. 1992, respectively. Plots were fertilized at from 58-59,000 acres planted the previous three years planting and sidedressed once at a rate of 91-29-91 and (Freie and Young, 1991). 30-0-28, (N-P-K) pounds per acre, respectively. Overhead Control of weeds is a major problem in sweet corn pro irrigation was used as needed. duction. An average annual loss of potential production of Experiments on organic soils were carried out in grow 10% has been estimated per year in sweet corn production ers fields in the Zellwood, FL, area. The 1991 trials were in the southeast (Losses due to weeds committee, 1984). on the Crakes Farms and in 1992 on the Lust Farms. The This loss may behigher in Florida due to year round weed soil at both sites was a Lauderhill muck (approx 60% OM) growth and the varying soil types. with a pH of 6.8. 'Showcase' seed was planted 25 Mar. Most of the sweet corn in Florida is grown on the or 1991 and 'Ultimate' 11 Mar. 1992 on 3 foot row centers in ganic soils of the Everglades and the Zellwood areas. Her a randomized complete block design. Maintenance of plots bicides cleared for use for preemergence control of ger was done according to grower practice except no cultiva minating annuals, especially grasses are more restricted for tion was used. Seep irrigation was used in both years. organic soils than mineral soils. Herbicides were applied using a CO2 powered back Alachlor has been restricted from use in Florida due to pack sprayer calibrated to deliver 30 gpa. In the mineral confirmed ground water contamination. Alachlor along soil, a 2 nozzle boom at 20 inches between nozzles were used. In the organic soil, the nozzles were on 18 inches Florida Agricultural Experiment Station Journal Series No. N-00750. centers. Post-directed sprays were applied with a single
326 Proc. Fla. State Hort. Soc. 105: 1992.
Table 3. Effects of postemergence herbicides on vigor and weed control in sweet corn in mineral soils, Gainesville, FL 1991-92.
Ratings (%)z
6-10-91 Rate Applic 6-15-92 Herbicide lb/A Timing Vigor AMACH^ RAPRA Vigor AMACH CHEAL DIGSP
Hoed Check 77 90 92 80 100 100 100 Weedy Check 75 0 0 78 0 0 0
Bromoxynil .375 EPOST? — — — 93 98 100 0
Bromoxynil .375 EPOST — — — 93 98 100 0 +Atrazine 1.0 Pyridate .45 EPOST 55 95 90 95 100 100 0 +Atrazine + COC 1 Pyridate .7 EPOST 77 100 100 95 98 100 0 +Atrazine + COC 1 Pyridate .9 EPOST 72 100 100 88 100 100 0 +Atrazine + COC .2 Sethoxydim .2 POST 62 0 0 85 0 0 80 +COC DIR Sethoxydim .2 POST 82 90 95 80 70 50 60 +Atrazine + COC 1 DIR Sethoxydim .2 POST 90 92 93 98 95 63 63 +Linuron + COC 1 DIR Linuron 1 POST 89 93 94 93 100 59 53 + COC DIR LSD (.05) 25 12 19 18 24 8 19 zRatings are 0 = no vigor (dead) or no control to 100 where no loss of vigor and complete control. See Table 1. y(AMACH) smooth pigweed, (RAPRA) wild radish, (CHEAL) lambsquarter, (DIGSP) crabgrass. "Application - (EPOST) early postemergence, (Post DIR) post directed.
plus atrazine treatments. Good control of smooth pigweed Control of purslane was significantly lower with was obtained even though the applications were not made bromoxynil alone than with bromoxynil and pyridate + over the tops of these weeds (Table 4). atrazine at Zellwood in 1992. Sethoxydim did not control, The bromoxynil and all 3 rates of pyridate plus atrazine nor was expected to control, purslane, but atrazine + provided excellent control of both smooth pigweed and sethoxydim and linuron treatments provided excellent lambsquarter at Gainesville in 1992. The post-directed control of this weed. linuron also provided excellent control of smooth pigweed Bromoxynil, bromoxynil + atrazine and all 3 rates of but control of lambsquarter was only fair. Both weed pyridate + atrazine provided no or poor control of crab- species were sprayed along the side of the plants at the grass and barnyardgrass in 1992. post directed stage. Smooth pigweed was killed, but Crabgrass was tall and extremely thick at Gainesville in lambsquarter was only partially controlled by this applica 1992. Control of crabgrass with sethoxydim and the tion. sethoxydim tank mix was better than with linuron alone.
Table 4. Effects of postemergence herbicides on vigor and weed control in sweet corn in organic soils, Gainesville, FL 1991-92.
Ratings (%)z 5-30-91 5-14-92 Herbicide lb/A Timing Vigor AMACHy PANDI Vigor POROL ECHCG
Weedy Check 70 0 0 100 0 0
Bromoxynil .375 EPOSTX — — — 88 73 20
Bromoxynil .375 EPOST — — — 90 95 43 +Atrazine 1.0 Pyridate .45 EPOST 75 73 78 98 98 50 +Atrazine + COC 1
Pyridate .7 EPOST — — — 88 94 50 +Atrazine + COC 1
Pyridate .9 EPOST — — — 86 94 45 +Atrazine + COC 1 Sethoxydim .2 POST 75 0 95 89 0 100 4-por
Sethoxydim .2 POST 83 33 84 96 94 89 +Atrazine + COC 2 DIR Sethoxydim .2 POST 78 70 98 100 99 99 + Linuron + COC 1 DIR Linuron 1 POST 65 78 88 100 98 78 + COC DIR LSD (.05) 13 25 18 10 14 34 zRatings are 0 = no vigor (dead) or no control to 100 where no loss of vigor and complete control. See Table 1. y(AMACH) smooth pigweed, (PANDI) fall pancum, (POROL) puslane, (ECHCG) barnyardgrass. "Application - (EPOST) early postemergence, (Post DIR) post directed.
Proc. Fla. State Hort. Soc. 105: 1992. 329 Reduction of control in these cases was primarily due to atrazine also increased its broadleaf activity. Application of lack of coverage and the size of the plants at treatment. At pendimethalin at the spike stage was safe and efficacious Zellwood in 1992, barnyardgrass was controlled very well, on mineral soils. On organic soils, preplant incorporation even though these grasses were very tall at the time of and preemergence applications should be tested. herbicide application. Bromoxynil and pyridate + atrazine were not Yield with linuron alone and linuron plus sethoxydim phytotoxicity and provided good postemergence broadleaf were significantly greater than with the weedy check, the control on both mineral and organic soils. low rate of pyridate + atrazine, sethoxydim alone and Sethoxydim and linuron are both labeled for use as sethoxydim + atrazine at Gainesville in 1991 (data not post-directed applications on sweet corn. Applied as a post shown). Sweet corn yield was not obtained at Zellwood in directed spray, they were both safe and effective, even 1991. A commercial harvesting crew started through the when tank-mixed. wrong field, unfortunately destroying the plots. Literature Cited Yield differences due to postemergence treatments either at Gainesville nor Zellwood in 1992 were not signif Freie, R. L. and H. V. Young, Jr. 1991. Florida Agriculture Statistics icant. Service, Orlando, Florida Federal State Market News Service 1992. Atrazine and metolachlor are labeled and used exten Vegetable Summary (1990-1991). Florida Dept. of Agr. and Con sively on the mineral soils in Florida. Metolachlor provided sumer Services. Tallahassee. Losses Due to Weeds Committee. 1984. Crop losses due to weeds in good grass control on organic soils when applied Canada and the United States. Special Report. Weed Science Society preemergence at 4 lb/acre and higher. Incorporation of of America. Champaign, 111. metolachlor with irrigation may be difficult on organic soils Monks, D. W., C. A. Mullins, and K. E. Johnson. Response of sweet corn under current commercial practices. Further tests should (Zea mays) to nicosulfuron and primisulfuron. Weed Tech. 6(2):280- be carried out on application of metolachlor preplant in 283. Stall, W. M. 1991. Weed Control in sweet corn. Florida Cooperative Ex corporated. tension Service. Fact Sheet VC-197. 4 pg. Pendimethalin also provides good grass control on or Stall W. M. and T. A. Bewick. 1992. Sweet corn cultivars respond diffe ganic soils applied at 0.75 to 2 lb/acre. Tank mixing with rentially to the herbicide nicosulfuron. HortScience 27(2): 131-133.
Proc. Fla. State Hort. Soc. 105:330-333. 1992.
THE ENERGY REQUIRED IN THE PRODUCTION OF VEGETABLES IN FLORIDA
Richard C. Fluck, C. Direlle Baird, seventh among all agricultural commodities in both direct and Balwinder S. Panesar and total primary energy requirements for production. Agricultural Engineering Department IFAS, University of Florida Estimates of the energy required in the production of Gainesville, FL 32611 Florida vegetables are few, varied and incomplete. Esti mates of energy consumed in 1974 (Federal Energy Ad Additional index words. FAECM, spreadsheet, model, direct ministration, 1976) (which included direct energy plus fer energy, total primary energy, energy consumption, to tilizers and pesticides but did not include other indirect energy inputs) were 30.1 million Btu/acre for tomatoes matoes. (Lycopersicon esculentum Mill.), 13.0 million Btu/acre for potatoes (Solamun tuberosum L.), 11.8 million Btu/acre for Abstract. A spreadsheet-based microcomputer model of energy watermelon [Citrullus lanatus (Thumb. & Nakai)], 12.6 mil consumption used in Florida agricultural production was de lion Btu/acre for snap beans (Phaseolus vulgaris L.), and veloped. The Florida Agricultural Energy Consumption Model 18.6 million Btu/acre for cabbage (Brassica oleracea var. (FAECM) quantifies 21 categories of direct (energy used di capitata L.). These per acre estimates extended to total rectly in the form of energy commodities) and indirect (energy energy consumption for Florida's statewide production in consumed in the provision of fertilizers, pesticides, machinery, 1974 were 990 billion Btu for tomatoes, 402 billion Btu for etc.) energy inputs required for producing each of approximately potatoes, 525 billion Btu for watermelon, 443 billion Btu 60 major and 30 minor crop and livestock commodities. Model for snap beans and 328 billion Btu for cabbage. Smerdon ing of the energy requirements for Florida-produced vegeta et al. (1974) also provided per acre and statewide estimates bles and melons was based upon nineteen vegetable budgets for diesel, gasoline and LP gas consumption for several and another budget for other vegetables. The model was vegetables. Using an input/output energy analysis ap based on production budgets converted to energy budgets, proach, Fluck (1975) also estimated the energy consumed and production levels (acres or number of head). in the production of vegetables in Florida. He found that The model, described in a companion paper in this vol the energy used for production in 1973-74 (excluding har ume, indicates that 4.79 trillion Btu's of direct energy and vesting) varied from 7 to 150 million Btu/acre depending 18.22 trillion Btu's of total primary energy (the sum of direct on the vegetable, and total (primary) energy for produc and indirect energy) was required to produce all Florida veg tion of 20 Florida vegetables to be 15.1 trillion Btu. Com etables in 1990. Tomato was first among vegetables and prehensive and complete assessments are needed that in clude all energy-requiring inputs to enable focusing of re Florida Agricultural Experiment Station Journal Series No. R-02761. This research was supported by the Florida Energy Office and the Florida search efforts to achieve better energy productivity and to Energy Extension Service. guide actions in response to potential energy shortages.
330 Proc. Fla. State Hort. Soc. 105: 1992.