Plant-Parasitic Nematode Management as a Component of Sustainable Soil Health Programs in Horticultural and Field Crop Production Systems

NON-TECHNICAL SUMMARY: Plant-parasitic nematodes such as root-knot, lesion and dagger nematodes, cause significant losses on agronomic and horticultural crops grown in the northeastern United States. Soil applications of chemical nematicides continue as the primary method for nematode management, especially on high value crops. Research to identify alternative nematode management options for fruits and vegetables based on nematode suppressive cover and rotational crops, biofumigants, and resistant cultivars, and the impact of selected cultural production practices on the diversity of nematode communities at the trophic level require significant research and integration into overall sustainable soil health management programs. Intensive production of crops in the northeast has resulted in a deterioration of soil quality, reducing yield and profitability. Causes of poor soil quality include: soil compaction, low organic matter, increased pressure from plant pathogens, insects and weeds, and lower density and diversity of beneficial soil organisms. Multi-disciplinary soil health teams in the United States and abroad have been established to address soil health issues and to develop long-term sustainable solutions. Progress has been made to date, including the development of cost-effective protocols for assessing soil health, increasing soil health literacy, facilitating soil health demonstrations by growers, and promoting multi-disciplinary research and outreach. Although nematodes have been used as biological models in science, relatively little is known about the relationships between soil health and management of plant-parasitic nematodes. There is a need to assess the impact of soil health interventions on nematode community structure dynamics and integrate nematode management into soil health programs. The expansion of the soil health component of this project is intended to develop biologically based nematode control practices compatible with overall soil health management practices. Northeastern agriculture and its associated polyspecific nematode communities offer challenges that are diverse and complex. Nematology, however, is only represented by a very small number of scientists. To achieve the objectives of this project, it is imperative for individuals to work together to achieve the objectives of this proposed project. The proposed multistate research project will: 1) enhance the economic viability of farms by saving costs associated with nematicide usage and 2) change the behaviors of farmers through extension and outreach to result in increased integrated management of nematodes, increasing sustainable soil health of small, medium and large farms throughout the northeastern region. In addition, farmers will have an increased understanding about nematodes, the damage they cause, and the key roles that these animals have in soil food webs. There will also be significant new knowledge added to the science of nematology.

<P> APPROACH: Objective 1. Develop effective and economically viable cultural management tactics for plant-parasitic nematodes based on host resistance, nematode antagonistic rotation or cover crops, soil amendments and biological agents. Scientists will search for resistance to Meloidogyne hapla and also root-lesion nematodes in vegetable small fruit, and rotational grain crops, and assess the impact of nematode-antagonistic rotational or cover crops on populations of lesion and root-knot nematodes. Crops such as rapeseed, marigold, forage and grain pearl millet, Rudbeckia hirta, sudangrass and sorgho-sudangrass will be evaluated for nematode suppressiveness against RKN, cyst, lesion or dagger nematodes. The toxicity of root exudates or plant breakdown products such as glucosinolates released from Brassica residues or the nematicidal residues from oats, sudangrass or sorgho-sudangrass will be evaluated in vitro or directly on nematodes in soil to determine the most efficacious use against particular nematode species. Brassica seed meals remaining after oil extraction may have high levels of glucosinolates and be portable, allowing application to target fields with nematode problems. <P>Objective 2. Evaluate cultural management procedures for plant-parasitic nematodes in relation to their impacts on the sustainability of soil health: with special reference to the utility of nematode community structure as an indicator of overall soil quality and their roles in plant nutrient cycling. The soil health assessment methodologies will consist of comparative analyses of alternative management systems using methods that have consistently been shown to reflect nematode community structure, management activity, productivity potential, and the ability to hold nutrients and resist degradation. We will assess nematode community structure based on trophic group. <P>Objective 3. Provide educational materials and programs on cultural management of plant-parasitic nematodes and sustainable soil health systems as a component of ongoing extension and outreach efforts. Results obtained under objectives 1 and 2 will be disseminated to extension educators, IPM practitioners, private consultants, growers, and agricultural service providers to promote a deeper understanding of the need to diagnose symptoms and signs of plant-parasitic nematode damage and the development of nematode management practices. In addition, generated research and outreach information will be posted on the regional project web page. Furthermore, field days and hands-on training will be held for diagnosing nematode damage, on-farm assessment of nematode soil infestations using simple and visual soil bioassays, and discussion of available nematode management options. Finally, results obtained will be presented at commodity group meetings, field days, and extension meetings as well as preparing extension bulletins, fact sheets, and scientific journal publications.