Location: Subtropical Plant Pathology Research
2013 Annual Report
Nematode, weed, and fungal populations at each field site and for each year will be assessed prior to treatment, immediately following treatment prior to crop establishment, at mid-season of the crop, and at the initiation of harvest.
A novel combination of organic acids was developed in collaboration between the University of Florida and the USDA, ARS Fort Pierce, FL. The combination, referred to as ‘SPK’ (U.S. Patent Application Serial Number 61/153,485) has shown great potential for controlling soilborne pests including fungi, nematodes, and weeds in laboratory, greenhouse, and field microplot trials. Objectives of the proposed research were to further evaluate efficacy as a methyl bromide alternative in high-value crop production systems currently dependent on soil fumigation; raised-bed strawberry and vegetable production in Florida. Few fumigants are currently available for control of soilborne pests in specialty crops. The recent removal of iodomethane, a promising “drop-in” replacement for methyl bromide, from the U.S. market has left only Telone®, chloropicrin (pic), metam sodium/potassium (metam), and dimethyl disulfide (DMDS, Paladin™). These materials are used in multiple combinations and all face regulatory limitations and are under scrutiny by the EPA based on their potential for by-stander exposure due to heightened concerns related to volatile organic compounds (VOCs). The ultimate goal of the proposed research was to identify a non-fumigant measure for the control of soilborne pests in specialty crops. Two strawberry trials were conducted to compare the experimental material to a chemical standard and to a non-fumigant approach to soilborne pest management. Two vegetable trials were aimed at determining if efficacy could be improved through rate manipulation and application technique. There were no measurable volatile organic compounds (VOCs) produced by the experimental material. The higher rate of the experimental material was more effective for pathogen control than was the low rate. Direct contact with the material is required for control of soilborne pathogens and movement of the experimental material is limited to the movement with water. Soil populations of Fusarium spp. Fusarium oxysporum, and Trichoderma were monitored throughout the trial. Immediately following treatment application, populations of Trichoderma spp., a potentially beneficial fungus, were significantly increased in plots treated with the experimental material and remained high throughout the season. Implication of this finding is extremely important for the use of this material as a methyl bromide replacement in the production of tree liners in the southeast, which require a Trichoderma population to prevent transplant failure. In the vegetable trials, all chemical treatments provided greater root-knot nematode suppression than found in the untreated check. Drip applied treatments were more effective for overall weed control. There were few significant differences found relative to crop yield.