Location: Citrus and Other Subtropical Products Research
2023 Annual Report
Objectives
1. Develop and improve non-fumigant crop production approaches to maximize efficacy and optimize crop productivity.
1a. Optimize anaerobic soil disinfestation (ASD) application for effectively managing soilborne pests and increasing plant health and yield.
1b. Combine ASD with novel crop production tools for increased value.
1c. Develop and implement adaptation of methyl bromide alternatives to soil fumigation, including non-fumigant approaches to management of nematodes and other pathogens in California carrot and strawberry production, such as anaerobic soil disinfestation.
2. Establish methods for improving soil health, plant nutrition, and pathogen management in greenhouse and other controlled environment production systems.
2a. Increase the environmental benefit of ASD through incorporation of reclaimed water for nursery production.
2b. Utilizing ASD to managing bacterial wilt in controlled environments.
2c. Ascertain methods to increase microgreen production and manage pathogens.
3. Characterize microbial communities and plant interactions that contribute to soil health and plant disease management.
3a. Identify abiotic and biotic factors that contribute to rootstock resistance breakdown.
3b. Characterize the relationship between the soil microbiome and plant health.
Approach
Soilborne plant pathogens, weeds, nematodes, and nutrient mismanagement cause considerable yield losses in vegetable and ornamental crops. In the Southeast, although methyl bromide was banned, soil fumigation remains a critical component in vegetables and fruits production. Alternative chemicals continue to be investigated, but only 1,3-dichloropropene, chloropicrin, an allyisothiocyanate biofumigant, and methyl isothiocyanate generators remain available. Dimethyl disulfide is registered, although there is currently no U.S. distributor. These materials, applied alone or in various combinations, do not provide the spectrum or level of control that resulted from the use of methyl bromide. Dependence on fumigation leaves growers vulnerable to regulatory and economic forces associated with pesticide use. Crop production systems, soil treatments, and nutrient management tools that control pests and maximize yield, while reducing negative environmental and human impacts, are the focus of the proposed research project on development and improvement of biological and cultural management strategies for pathogens and weeds impacting fruit, vegetable, and ornamental crop yields. These systems will be assessed holistically for their potential impact on the environment and product quality. An integrated approach of improving and understanding the role of the soil microbiome, soil quality, and plant nutrition in mitigating impacts of biotic and abiotic stressors will result in regenerative agricultural practices that increase crop productivity. While independent research will be conducted in laboratories, greenhouses, and in the field, ongoing and new collaborations with other ARS, university, and industry researchers will broaden the scope of the research. Continued stakeholder engagement is critical for effective technology transfer and for ensuring practical tool delivery. Mitigating the impact of soilborne pests impacting crop production while improving U.S. agroecology aligns with the USDA-ARS mission, “to sustain a competitive agricultural economy".
Progress Report
ARS scientists at Fort Pierce, Florida, have established experiments to optimize anaerobic soil disinfestation (ASD), a non-chemical fumigant approach to manage soilborne pathogens, pests, and weeds in accordance with Objective 1. Collaborating with teams from University of Florida, these scientists conducted strawberry field experiments across Florida to determine the optimal soil amendments rate, pasteurized broiler litter and molasses. Even though hurricanes disrupted application, planting, and sampling schedules, the team believes they have discovered the optimal ratio of soil amendments for ASD application in strawberry and will test their hypothesis this fall. Additionally, to fulfill subobjectives 1a and 1c, on-farm trials were established to determine the efficacy of ASD in managing nematodes and soilborne plant pathogens for novel crops, such as carrot, winter melon, and jicama. Carrot trials were recently established with collaborators from University of California. The data collected from the winter melon trials is being analyzed. The first trials for jicama demonstrated that jicama plants grown in ASD treated soil weighed on average 8% more than plants grown in non-treated soil.
Sub-objective 1b: Innovative tools were incorporated with ASD to increase pest management and adoption of ASD. An on-field trial has been setup to determine if combining halosufuron, an herbicide, with ASD would result in decreased anaerobicity and ability to manage soilborne pathogens and pests. Organic growers have expressed concern for using single use plastic, thus a field experiment was conducted in which two different biodegradable mulches were compared to high density embossed polyethylene mulch and totally impermeable film, the recommended mulch. Both biodegradable mulches were difficult to apply compared to the other two types.
Objective 2 consisted of experiments to improve plants productivity in controlled environments. Reclaimed water was tested from 7 different location and at multiple time points for Subobjective 2a. It was hypothesized that reclaimed water would be nutrient rich, thus decreasing fertigation. Discovered that nutrient content in reclaimed changes spatially and temporally. Additionally, concerns have been raised about heavy metals and pharmaceuticals in reclaimed water.
Sub-objective 2b: Soil spiked with the soilborne plant pathogen, Ralstonia solanacearum, has been setup and the experiment for testing blueberries will be established this next month. Primers and protocol for qPCR have been developed.
Microgreen trails have been setup and biometric was taken in accordance with 2c. Data has been collected and needs to be analyzed.
Objective 3 consists of understanding the role microbial communities contribute to soil health and disease management. Sub-objective 3a: Tomatoes were grown in growth chambers at different temperatures to determine if nematode resistance breakdown was dependent on temperature. Tomatoes were grown in two different types of field soil and potting soil to determine if soil nutrients, soil microbial communities, or other factors contribute to resistance breakdown.
Sub-objective 3b: Greenhouse experiment in growing tomatoes in different soil types was also setup and is ongoing.
Accomplishments
1. Adapting anaerobic soil disinfestation for Florida strawberry growers. Strawberry growers are in desperate need of new techniques for managing soilborne plant pathogens and pests as the current disinfestation techniques are subjected to the price of oil, banned due to being hazardous to environment and human health, subjected to limited use as buffer zones increase and urban sprawl. Driscoll’s along with traditional and organic strawberry growers believe that anaerobic soil disinfestation (ASD) could be a solution. However, ASD in Florida was formulated for tomatoes, and additional nitrogen into the cropping system could cause the strawberry plants to increase runner plants instead of fruit production and fruit exposed increased nitrogen will increase fruit degradation. Thus, ARS scientists from Fort Pierce, Florida, in collaboration with University of Florida conducted multiple field studies to determine the best ratio of carbon (molasses) and nitrogen (pelletized poultry litter) for yield, plant health, and soilborne pathogen and pest management. Demonstration trials comparing ASD and ASD with soil solarization have been established on four commercial strawberry farms.
2. Assessing the viability of growing low sugar high water crops in Florida. Beverage companies have expressed interest in growing crops that are high in water and low in sugar. One of these crops is jicama, which is not widely planted in Florida. However, which common plant pathogens or pests might limit jicama production was unknown. ARS scientists from Fort Pierce, Florida, conducted various greenhouse experiments to determine if the three common root knot nematodes species could infect jicama. Two different types of jicama were tested and the tubers were assessed temporally. It was discovered that galling was sporadic and as the tuber matured the incidence of infection was less frequent. Twelve weeks post inoculation only 4 tubers out of 40 had minor galling where 1-5 nematodes were counted on 100 cm3 of roots. Based on these results, root knot nematodes should not be an issue for jicama. This study is currently being repeated.
Review Publications
Di Gioia, F., Hong, J.C., Pisani, C., Petropoulos, S., Bai, J., Rosskopf, E.N. 2023. Yield performance, mineral profile, and nitrate content in a selection of seventeen microgreens species. Frontiers in Plant Science. 14 : Article 1220691. https://doi.org/10.3389/fpls.2023.1220691.
Vincent, I., Paudel, B., Guo, H., Rosskopf, E.N., Di Gioia, F., Hong, J.C., Mcnear, D., Xu, N., Anrecio, L., Colee, J., Zhao, X. 2023. Spatial and temporal changes of soil microbial communities in field tomato production as affected by anaerobic soil disinfestation. Frontiers in Sustainable Food Systems. https://doi.org/10.3389/fsufs.2022.838635.
Rosskopf, E.N., Di Gioia, F. 2023. New approaches to soil disinfestation for specialty crops. Handbook of Vegetable and Herb Diseases. https://doi.org/10.1007/978-3-030-35512-8_12-1.
