CCEUC Role: Project lead (collaborators: CCE Suffolk, Cornell University, Cornell Vegetable Program)
Why: Crop loss from soil-borne pathogens, in particular Phytophthora capsici, are increasingly a threat to vegetable production in the humid northeastern US (including the northeastern Midwest). Vegetables are high value per-acre crops that play key economic roles in sustaining agricultural vitality in this region. Vegetables affected by soil-borne pathogens are global and widespread. Phytophthora blight (PB) affects a diversity of crops including all cucurbit crops (squash, pumpkin, cucumber, etc), pepper, eggplant, tomato, and snap beans; all are important crops in vegetable growing regions of the northeast and annually constitute at least 300,000 acres of cropland. In 2011, flooding following Hurricane Irene and Tropical Storm Lee highlighted how soil-borne pathogens like Phytophthora capsici can be spread in floodwaters and leave legacies of production challenges for vegetable growers. For instance, nearly every vegetable grower with floodplain acreage in Ulster County, NY, has reported substantial economic losses from PB since 2011. Phytophthora capsici is now likewise established in 25 NY counties with some strains showing resistance to fungicides, and the pathogen has been detected in 100% of surface irrigation sources surveyed in two regions of the state. Phytophthora capsici, a water mold, is tenacious in soils after introduction, persisting ~10 years + without a host present; once introduced, growers with infested fields may commonly lose 30% of susceptible crops to PB on average and up to 80-100% in wet years. Growers currently mostly rely on fungicide programs to suppress PB infection, with some integrating sanitation measures (cleaning equipment, culling etc.) and strategies to manage water/promote drainage in their fields (raised beds, subsoiling, etc.). For many growers though, this disease can be game-changing and compromise farm viability. Phytophthora blight is not expected to subside as a transient disease epidemic because of climatic changes occurring in the northeast. Increases in heavy rainfall events have been correlated with climate change trends, and are expected to continue to be a characteristic of the northeastern US climate in the next century. The threat of increased flash flooding and standing water in fields from heavy rainfall events highlights that 1) soil-borne diseases such as PB are going to be increasingly widespread and menacing to crop production, and 2) soil management and water management will be increasingly important for farmers to sustain their soil resources and the resiliency of their farm to the effects of extreme weather.
What: Two strategies will help growers adapt to the threats of increased heavy rainfall events that provide ideal conditions for both the spread and development of soil-borne pathogens like Phytophthora capsici: 1) improved soil health management for mitigating effects of heavy precipitation loads, and 2) integrated soil-borne pathogen management strategies that reduce inoculum over time. Reduced tillage practices have been well documented as an economical long-term investment into improving soil health, improving drainage and reducing pathogen loads, although the latter is a less recognized benefit. Reduced tillage is still in the earlier stages of adoption in vegetable production, and would benefit from quantifying effects on PB. Cover crops additionally aid in managing water loads in fields by stabilizing and protecting soil structures, and creating root channels that promote infiltration. Brassica cover crop taproots can be particularly effective in facilitating drainage and are additionally known to recover residual nitrogen exceptionally well from deeper soil layers because of their ability to rapidly root deeply. A unique aspect of certain brassica crops is their ability to produce high levels of compounds (glucosinolates) that chemically transform into a broad-spectrum soil fumigant (isothiocyanate) upon incorporation into soils and contact with water (hydrolysis). Preliminary studies illustrate the potential of biofumigating brassica cover crops for soil health and soil-borne disease management. In a Washington State potato study, brassica cover crops for biofumigation increased soil infiltration rates by 2 to 10x and lowered soil-borne pathogen and nutrient management costs by $66/ac. In studies in Georgia and New York, brassica biofumigation improved yields in squash by 14-21% and 30-36% and reduced PB infections by 75% and 56-72%, compared to untreated controls and a fungicide treatment, respectively. Based on these promising results, We anticipate that growers adopting practices including brassica biofumigation will potentially gain a powerful tool for reducing inoculum that have been introduced into soils, while simultaneously gaining other indirect benefits from cover cropping with brassica crops. We also anticipate that growers who integrate brassica biofumigation with reduced tillage will gain an additional tool that works towards the long-term maintenance of soil health and soil-borne pathogen control, and enables growers to stabilize the effects of working in an environment that increasingly threatens soil resources and exacerbates the spread of diseases like PB. Without effective integrated management strategies, PB will be increasingly game-changing for northeastern growers and farm viability.
How: Our project will work to refine integrated management strategies that combat soil-borne diseases like PB for growers through an integrated soil health enhancement approach including, but not limited to, biofumigation and reduced tillage. Our research will be conducted through a plot-scale study, and a participatory on-farm study. Six NY growers battling PB will be targeted for engagement in research and demonstration trials. These growers will 1) be guided through the trial process, 2) elucidate barriers to adoption, and 3) serve as peer mentors to area growers for adoption diffusion. Research results will be compiled for growers into educational materials including quantitative reports, management recommendations, records of producer experiences, a webinar, and an instructional video. Grower mentors and Extension will disseminate information and materials through field days, local/regional/national conferences/meetings, grower and research publications, and Extension websites that will reach beneficiaries nationwide. Information from this project provide growers with the ability to pragmatically assess, successfully adopt, and viably utilize practices that can be integrated to help control PB and other soil-borne diseases, enhance soil health, and recover significant crop value.
For more details see: https://projects.sare.org/sare_project/lne14-335/
Last updated January 30, 2018