CEU Series: Fumigation Factors For The Future

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Soil fumigation is typically considered a necessary component of production for many crops grown in Florida such as tomatoes, peppers, eggplant, and strawberries. Fumigation is the pre-plant treatment of soil with a broad spectrum pesticide for the control of soil-borne diseases, weeds, and nematodes. The objective of fumigation is to establish an adequate concentration of the fumigant in the pest zone and maintain that concentration for sufficient time to kill the target pest. Soil fumigants are typically liquid materials packaged under high pressure that volatilize into a gaseous form when released.

The most widely adopted fumigant was undoubtedly methyl bromide. Its use was considered common practice in raised bed plastic mulch systems throughout the Southern U..S until its mandated phase-out in 1993 by the Clean Air Act and Montreal Protocol. The final phase-out date for new production and importation was January 1, 2005. At that point, growers were still able to use available, existing stocks and new stocks approved through the Critical Use Exemption (CUE) process. Through the CUE process, states submit applications for limited amounts of methyl bromide usage where necessary for successful crop production. In Florida, CUE petitions are created and submitted by the Florida Fruit and Vegetable Association (FFVA) with help from growers, commodity representatives, researchers and extension agents. From 2005-2013 CUEs have been awarded for Florida tomato, strawberry, pepper and eggplant production. CUE allocations are measured as a percentage of the amount of methyl bromide produced in 1991, referred to as the 1991 baseline. Allocations have steadily decreased and have nearly diminished to zero in 2013 with only 2.2% of the 1991 baseline approved. There will be no CUE allocation available in 2014. In August 2013, a petition was submitted requesting allocations for 2015 (supplemental) and 2016. This includes a “rescue treatment” for methyl bromide for use in critical situations. The amounts requested represent almost a 90% reduction from the pre phase-out period.

Since the phase-out began, growers have slowly adjusted to the use of methyl bromide alternatives, with the majority of the industry completely relying on their use in 2013. The transition has not been seamless, and issues continue to arise with their long term use. In the early transition period, 2005-2008, many growers used existing stocks of methyl bromide. In 2008, it was evident that there were shortages in supply and the need for successful alternatives was apparent. Growers were surveyed in 2011-2012 to determine: 1) what alternatives they were using, 2) what pest problems are arising due to their use 3) what additional Integrated Pest Management (IPM) practices are being implemented and 4) production losses associated with alternative use. Grower responses were used to develop a case for the “rescue treatment” and CUE petitions.

Crystal Snodgrass is a UF/IFAS Extension Agent based in Manatee County.

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