Improve High Tunnel Sustainability through Biological Control of Root-knot Nematodes

Commodities

Practices

High tunnel production is increasing rapidly in the NC-Region because of its effectiveness in extending vegetable production seasons. However, elevated soil temperature, constant soil moisture and lack of crop rotation in high tunnels lead to the buildup of plant-parasitic nematodes (PPN) in soils. Among them, root-knot nematodes (RKN) have a broad host range and damage roots of tomatoes and other specialty crops. Tomato is one of the most profitable vegetable crops in high tunnel production. Growing RKN-resistant tomato cultivars or grafting onto resistant rootstocks provide an effective method to manage RKN in high tunnels. Unfortunately, all of the RKN-resistant tomatoes carry the same resistance gene Mi-1 and Mi-1-mediated resistance is significantly compromised when soil temperature exceeds 28°C. The soil temperature in high tunnels can easily go above 28°C during summer, which comprises the effectiveness of tomato resistance against RKN. Lack of diversity in resistance has led to the emergence of virulent RKN populations which can overcome the Mi­-1 resistance in tomato. The team had already identified two virulent populations of the southern root-knot nematode (Meloidogyne incognita) that are able to break the tomato resistance in two high tunnels of Indiana. Such virulent RKN populations had been reported in tomato fields of California and Georgia. Emergence of virulent RKN populations make it more difficult for vegetable growers to manage the RKN pest.

Bio-control of RKN using beneficial microbes serve as an environmental-friendly method for nematode management. However, the commercial bio-control products sometimes lack consistency to manage RKN in different fields, partially due to failure of the beneficial microbes to establish well in different soil conditions. The aim of the project is to study the RKN and nematode-antagonistic microbes’ distribution in high tunnel soils and the correlation of their distributions with high tunnel crop management practices and soil properties in Indiana. We will further test the efficacies of bio-control products and new beneficial fungi identified by the team to suppress RKN infection of tomatoes using high tunnel soils with different chemical and physical properties under different temperatures and moisture levels in controlled environment. The analyses will help to identify application methods of bio-control products and soil properties that are important to increase the efficacy of bio-control products. We will collaborate with growers and evaluate efficacies of commercial bio-control products for RKN management in high tunnels. The project information will be delivered through multiple outreach channels to high tunnel growers in the NC-Region.

Objectives:

1. Understand plant-parasitic nematodes (PPN) and nematode-antagonistic microbes distribution in high tunnel soils and correlation of their distributions with soil properties and farming practices.
2. Evaluate efficacy of PPN bio-control fungi in reducing RKN infection of tomatoes, and investigate influence of soil texture, organic matter, temperature, and soil moisture in a controlled environment.
3. Test efficacies of commercial bio-control products for managing RKN in high tunnels and understand the economic feasibility of using these products.

Outcome:

Learning: improved growers’ knowledge regarding PPNs and biological control.

Action: implementation of integrated management of PPNs.

System: improve high tunnel system sustainability and productivity.