Location: Citrus and Other Subtropical Products Research
2021 Annual Report
Objectives
1. Identify natural products and crop production systems that contribute to management of soilborne diseases, weeds, and nematodes.
1a. Develop combinations of commercially-available allylisothiocyanates (AITC) with organic amendments and other crop protection tools to improve weed, disease, and nematode control.
1b. Develop strategies to eliminate obstacles to the use of dimethyl disulfide.
2. Optimize application of anaerobic soil disinfestation (ASD) for application in vegetable and ornamental production.
2.a. Determine minimal input requirements and optimize organic amendments for effective application of ASD.
2.b. Increase environmental benefit of ASD through incorporation of reclaimed water.
3. Identify rootstocks for use with grafted vegetables with resistance or tolerance to pathogens and root-knot nematodes.
3a. Characterize rootstocks and associated microbiome for resistance or tolerance to soilborne pathogens of importance in the Southeastern U.S.
3b. Determine nutritional requirements and capacity of grafted plants to mitigate abiotic stress related to water quality.
Approach
The loss of methyl bromide for soil fumigation, limited registration of new chemical fumigants, and increased regulation of existing chemical fumigants has caused significant changes to crop production practices, including the registration and utilization of biofumigants and non-fumigant systems. Newly registered compounds, used alone or in combination, do not provide the same level of pest control resulting from the use of methyl bromide. Recognizing that some of the currently-registered chemical fumigants may, in the future, follow the same path as methyl bromide, the emphasis of the current research project will be to enhance the efficacy and understand the mechanisms of biologically and culturally-based management strategies for pathogens, weeds, and nematodes impacting vegetable and ornamental crops. Efficacy of management components will be examined individually and in combinations to achieve improved control of pathogens previously managed through soil fumigation using methyl bromide and to mitigate abiotic stress. Although some tactics have shown significant efficacy against individual pests or problems, integrated systems that address pest complexes are limited. It is critical that broad-spectrum pest control is achieved and approaches are compatible with the USDA, ARS mission to sustain a competitive agricultural economy by addressing pests that impact crop production as well as improving the health of the agro-ecosystem. Developed strategies will be built upon to gain a better understanding of pest biology, plant nutrition, pathogen and non-pathogen microbial interactions, and the impacts of pest control practices on the development of disease, weed, and nematode suppressive soil. Laboratory, greenhouse, and field experiments will be conducted independently, and in cooperation with ARS and University researchers, and through agreements with industry to broaden the scope of the research. Continued engagement with grower and industry partners will ensure effective transfer of technology which will include more efficient and environmentally compatible crop production systems that minimize health risks to workers and bystanders, and reduce inputs and environmental pollution from pesticides and fertilizers.
Progress Report
All replicated field trials for the evaluation of allylisothiocyanate (AITC) in cut flowers and vegetables were completed by ARS researchers in Fort Pierce, Florida, for multiple species. AITC was applied alone or in combination with herbicide active ingredients dithiopyr, oxyfluorfen with isoxaben, or a formulation containing trifluralin, isoxaben, and oxyfluorfen.
Second year field trials were completed by ARS researchers in Fort Pierce, Florida, on the impact of totally-impermeable film selection on the efficacy of anaerobic soil disinfestation to control yellow and purple nutsedge and strawberry crop productivity.
Second year carbon replacement trials were completed by ARS researchers in Fort Pierce, Florida, and most effective pathogen control was achieved with a standard rate of pelleted poultry litter combined with liquid molasses as the carbon source. Potential for nitrogen release, either as a nitrous oxide or through leaching potential, was impacted by carbon source selection.
In first year trials, addition of biochar to the surface of dimethyl disulfide fumigated soil prior to polyethylene film application resulted in reductions in the detection of dimethyl disulfide below the plastic.
First year greenhouse trial with microbe slurry was conducted by ARS researchers in Fort Pierce, Florida, in which field soil was treated with slurry, ASD and slurry, half rate of ASD and slurry, ASD, and non-treated control. None of the treatments was deleterious for tomato plant health. DNA from samples are being extracted.
Accomplishments
1. Polyethylene film selection influences nutsedge control by anaerobic soil disinfestation (ASD). Application of organic amendments for anaerobic soil disinfestation (ASD) have primarily targeted soilborne plant pathogens and nematodes, but can also impact weeds. Nutsedges are a weed of principal concern in areas in which ASD is being adopted for annual crop production. Experiments were conducted by ARS researchers in Fort Pierce, Florida, to evaluate ASD treatments conducted under various commercially-available 1-mil thickness totally-impermeable films (TIF) on emergence of mixed populations of Cyperus esculentus (yellow nutsedge) and C. rotundus (purple nutsedge). Film type influenced the level and duration of anaerobicity achieved as well influencing the number nutsedge shoots emerging through the plastic, although anaerobicity and nutsedge suppression were not correlated.
2. Dimethyl disulfide combined with chloropicrin is effective for managing soil plant pathogens, nematodes, and nutsedge. However, dimethyl disulfide has a pungent odor, which has been described as decaying fish or overpowering garlic, and the public have complained when dimethyl disulfide has been applied in fields closed to developed areas. Biochar, sourced from oak, was mixed into a 10 cm depth of soil, and soil was fumigated with dimethyl disulfide. ARS researchers in Fort Pierce, Florida, used a fourier-transform infrared spectrometer to detect and identify gasses under the plastic mulch, dimethyl disulfide was detected in soils treated with the chemical, but minimally detected in when dimethyl disulfide was combined with biochar. Additionally, dimethyl disulfide plus biochar reduced the average amount of nutsedge compared biochar alone or the non-treated soil.
Review Publications
Shrestha, U., Ownley, B., Bruce, A., Rosskopf, E.N., Butler, D. 2020. Anaerobic soil disinfestation efficacy against fusarium oxysporum is affected by soil temperature, and amendment type, rate and c:n ratio. Phytopathology. https://doi.org/10.1094/PHYTO-07-20-0276-R.
Vecchia, L., Digioia, F., Ferrante, A., Hong, J.C., White, C., Rosskopf, E.N. 2020. Integrating cover crops as a source of carbon for anaerobic soil disinfestation. Agronomy Journal. p.1614. https://doi.org/10.3390/agronomy10101614.
Garcia Chance, L., Albano, J.P., Lee, C., Rovder, A., White, S. 2020. Alkalinity of irrigation return water influences nutrient removal efficacy of floating treatment wetland systems. Journal of Environmental Horticulture. 38(4), pp.128-142.. https://doi.org/10.24266/0738-2898-38.4.128.
Hwang, J., Hinz Ordonez, F., Albano, J.P., Wilson, P.C. 2020. Enhanced dissipation of trace level organic contaminants by floating treatment wetlands established with two macrophyte species: A mesocosm study. Chemosphere. 267, p.129-159.. https://doi.org/10.1016/j.chemosphere.2020.129159.
Schulker, B., Jackson, B., Fonteno, W., Heitman, J., Albano, J.P. 2020. Comparison of water capture efficiency through two irrigation techniques of three common greenhouse soilless substrate components. Agronomy. 10:1989. https://doi.org/10.3390/agronomy10091389.
Garcia Chance, L., Majsztrik, J., Bridges, W., Willis, A.S., Albano, J.P., White, S. 2020. Comparative nutrient remediation by monoculture and mixed species plantings within floating treatment wetlands. Environmental Science and Technology. 54(14):8710-8718. https://doi.org/10.1021/acs.est.0c00198.
Rosskopf, E.N., Di Gioia, F., Hong, J.C., Pisani, C., Burelle, N.K. 2020. Organic amendments for pathogen and nematode control. Annual Review of Phytopathology. (58):277-311. https://doi.org/10.1146/annurev-phyto-080516-035608.
