Location: Citrus and Other Subtropical Products Research
2018 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
The first year field trials for the evaluation of allyl isothiocyanate (AITC) in vegetables were completed. Trials were conducted in both bell pepper and tomato comparing commercial AITC with and without the herbicide fomesafen. Plots treated with AITC, regardless of herbicide application, resulted in more tomato and pepper fruit than untreated plots. Nutsedge control was significantly improved with fomesafen application. On-farm field trail, utilizing chitin amendments in combination with AITC, were conducted using multiple cut flower species. Soil samples were collected and processed for deoxyribonucleic acid (DNA) extraction and length heterogeneity polymerase chain reaction (LH-PCR) reactions were conducted focused on amplification of both bacterial and actinomycete populations. Soil and root samples were collected and processed for root-knot nematode population densities from three cut flower crop species. Marketable yield was collected based on the grower standard.
Field trials were established in which repeated applications of dimethyl disulfide were conducted. Soil samples were collected prior to and following each fumigation event. Total DNA was extracted from soil samples and extracts have been prepared for LH-PCR analysis. Materials for odor mitigation have been identified and small-scale laboratory evaluations have been completed to determine field-applicable rates on chlorine dioxide. Sources of biochar have been identified and collected.
Carbon and nitrogen content have been characterized for multiple potential carbon sources, including rice bran, citrus molasses, pelleted citrus waste, beet molasses, glycerol, green plant biomass of three potential cover crops, lactose, and two types of whey. Protocols for determining labile carbon have been established. Laboratory-scale micro-chambers have been established for controlled fermentation studies for bacteria associated with generation of anaerobic conditions and organic acid production during anaerobic soil disinfestation. Chambers were designed with multiple collection ports to extract gases and organic acids during the fermentation process.
In collaboration with Clemson University and Virginia Tech University as part of the Specialty Crops Research Initiative project, WaterR3, degraded water sources adapted for irrigation of horticultural crops were analyzed for macro- and micro-nutrients and chemistry (i.e. pH, electrical conductivity, and alkalinity).
More than 25 tomato, pepper, and cucurbit rootstock accessions have been collected from both research and commercial institutions for evaluation of nematode and soilborne pathogen resistance. Preliminary trials have been conducted to determine seed germination rates and timing required for grafting procedures.
One greenhouse trial was completed on the impact of high saline water on commercial bell pepper. The impact of salinity combined with the crown rot pathogen Phytophthora capsici was quantified via disease progress, pepper yield, biometric assessment, and rate of photosynthesis. Plant tissue nutrient analysis was conducted to determine the partitioning of sodium in plant parts.
Accomplishments
Review Publications
Di Gioia, F., Rosskopf, E.N., Leonardi, C., Giuffrida, F. 2018. Effects of application timing of saline irrigation water on broccoli production and quality. Agricultural Water Management. 203:97-104.
Shennan, C., Muramoto, J., Koike, S., Baird, G., Fennimore, S., Samtani, J., Bolda, M., Dara, S., Daugovish, O., Lazarovits, G., Butler, D., Rosskopf, E.N., Burelle, N.K., Klonsky, K., Mazzola, M. 2018. Anaerobic soil disinfestation is an alternative to soil fumigation for control of some soilborne pathogens in strawberry production. Plant Pathology. 67(1):51-66.
Johns, C., Lee, A., Springer, T., Rosskopf, E.N., Hong, J.C., Turechek, W., Burelle, N.K., Finley, N. 2017. Using NMR-based metabolomics to monitor the biochemical composition of agricultural soils: a pilot study. European Journal of Soil Biology. 83:98-105. https://doi.org/10.1016/j.ejsobi.2017.10.008.
Xu, S., Li, J., Baldwin, E.A., Plotto, A., Rosskopf, E.N., Hong, J.C., Bai, J. 2018. Electronic tongue discrimination of four tomato cultivars harvested at six maturities and exposed to blanching and refrigeration treatments. Postharvest Biology and Technology. 136:42-49. https://doi.org/10.1016/j.postharvbio.2017.10.004.
Rosskopf, E.N., Charudattan, R., Bruckart, W. 2017. Bioherbicides: An Overview. In: Zimdahl, R.L., editor. Integrated weed management for sustainable agriculture. Cambridge, UK:Burleigh Dodds Science Publishing. p. 367-392.
Guo, H., Zhao, X., Rosskopf, E.N., Hong, J.C., Mcnear, D. 2018. Impacts of anaerobic soil disinfestation and chemical fumigation on soil microbial communities in field tomato production system. Applied Soil Ecology. 126:165-173. https://doi.org/10.1016/j.apsoil.2017.12.018.
Rosskopf, E.N., Pisani, C.N., Di Gioia, F. 2018. Crop-Specific Grafting Methods, Rootstocks and Scheduling-Tomato. In: Kubota, C., Miles, C., and Zhao, X., editors. Grafting Manual: How to Produce Grafted Vegetable Plants. SCRI Vegetable Grafting Org. p. 1-13.
Shrestha, U., Rosskopf, E.N., Butler, D.M. 2018. Effect of anaerobic soil disinfestation amendment type and C:N ratio on Cyperus esculentus tuber sprouting, growth and reproduction. Weed Research. https://doi.org/10.1111/wre.12318.
