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United States Department of Agriculture

Agricultural Research Service

Research Project: Alternatives to methyl bromide soil fumigation for vegetable and floriculture production

Location: Subtropical Plant Pathology Research

Title: Chemical alternatives to methyl bromide for Florida ornamental production)

Author
item Rosskopf, Erin
item Burelle, Nancy
item Nissen, Eric
item Nissen, Ole
item Hartman, Bob
item Skvarch, Ed
item Brooks, Shan
item Mcsorley, Robert
item Owens, Clay

Submitted to: Proceedings of Methyl Bromide Alternatives Conference
Publication Type: Proceedings
Publication Acceptance Date: 10/11/2009
Publication Date: 10/15/2009
Citation: Rosskopf, E.N., Burelle, N.K., Nissen, E., Nissen, O., Hartman, B., Skvarch, E., Brooks, S., Mcsorley, R., Owens, C. 2009. Chemical alternatives to methyl bromide for Florida ornamental production. Proceedings of Methyl Bromide Alternatives Conference. 37:1-3.

Interpretive Summary:

Technical Abstract: This project is a cooperative effort among USDA, ARS and University of Florida researchers, Florida in-ground ornamental producers, and fumigant industry representatives. Funding is provided through the USDA-ARS Area-wide Pest Management Program for Alternatives to Methyl Bromide. The ornamental industry faces unique problems with respect to implementation of alternatives to methyl bromide for soil fumigation. Problems include proximity to urban areas, use of flat fumigation requiring gluing of wide VIF tarps, and large varieties of crops and cultivars produced, making development of disease and nematode resistance difficult, and necessitating control of rogues in successive crops. Studies were designed to test the efficacy of the available chemical alternatives, Midas™ (iodomethane:chloropicrin (pic) 50:50 [MI 50:50] and 98:2 [MI98:2], Arysta LifeScience Corp., Cary, NC) and dimethyl disulfide:pic (Paladin™ 79:21 [DMDS], United Phosphorous, Inc., King of Prussia, PA) compared with methyl bromide (MeBr). All fumigants were applied with standard equipment by commercial applicators. Trials were conducted in two locations in commercial cut flower and caladium production fields. Studies were replicated, randomized complete blocks with split plots to accommodate multiple cultivars. Treatments were applied in exactly the same plots over multiple seasons. Two years of research on delphinium has been completed, with the second year of trials on caladium on-going. The delphinium trial was performed in Hobe Sound, FL, and treatments were MeBr 400lb/A (98:2), MI 50:50 at 300 lb/A, and DMDS (79:21) at 74 gal/A. Treatments were replicated three times with each main plot measuring 26’ x 110’. Plots were split to contain two rows each of delphinium cultivars ‘Belladonna’ and ‘Bellamosum’. All materials were applied by commercial applicators using standard broadcast application equipment and 1 mil clear plastic mulch (Cadillac). A second study on caladium was located in Zolfo Springs, FL. Preliminary data was collected from a trial conducted by the grower which included a standard application of MeBr (360 lb/A of 89.5:10.5 MeBr:pic) compared to MI 50:50 (300 lb/A) and DMDS (79:21 at 74 gal/A). All materials were applied as previously described with the addition of a prefumigation deep shank application of Telone C-35 at 12-14” over the entire test area. Each treatment was replicated four times and each plot ranged from 0.23 to 0.28 A, and were planted to the cultivar White Queen. The first year of the area-wide trial at Zolfo Springs included two formulations of MI 98:2 (100 lb/A) and MI 50:50 (160 lb/A), DMDS (79:21 at 60 gal/A), and MeBr:pic (98:2 at 180 lb/A), all applied under high barrier, Blockade® plastic mulch (Pliant Corp., Chippewa Falls, WI) using raised beds. A deep shank application of Telone C-35 was applied as previously described. Each treatment was replicated four times and split into sub-plots planted to four cultivars. In all trials, nematode and fungal populations were assessed prior to fumigation, two-to-five days following tarp removal, at mid-season, and at harvest. In-field disease ratings were performed as needed through the season, continuing through root condition ratings at harvest. Plots were harvested by the growers. Dominant weed species were identified and time-to-weed data was collected by the growers. Galling was assessed and nematodes were extracted from roots at harvest. In delphinium trial there were no significant differences between treatments with regard to total weeding time. Cultivar ‘Bellamosum’ had significantly higher germination than the ‘Belladonna’, but this was not related to soil treatment. ‘Bellamosum’ plants in the MI 50:50 treatments were the fastest growing plants, but early in the season there were a greater number of cut stems harvested from the MeBr and DMDS ‘Bel

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