Grafting Rootstocks onto Heirloom and Locally Adapted Tomato Selections to Confer Resistance to Root-knot Nematodes and other Soil Borne Diseases and to Increase Nutrient Uptake Efficiency in an Intensive Farming System for Market Gardeners

View the project final report

• 2006 annual report
• 2007 annual report

Commodities

• Vegetables: tomatoes

Practices

• Production Systems: general crop production

Profitable organic and sustainable tomato production is difficult in the Southern Region. Many growers have moved into covered culture systems (high tunnels) in order to decrease foliar diseases, increase productivity, and improve economic stability through season extension. Utilizing tunnels limits rotation options, however, which increases soilborne disease pressure, ultimately resulting in crop failures. This problem is particularly difficult for growers who have developed high-end specialty markets based on traditional or heirloom varieties lacking genetic resistance to soilborne diseases. Sustainable and organic growers need research and extension support to implement methods enhancing tomato production and decreasing disease problems. The use of integrated systems utilizing both covered culture and grafting should be a promising strategy to help growers in the SE-USA. We propose implementing a series of strategic experiments to test performance of heirloom tomatoes grafted onto resistant rootstocks in open field systems and in synergy with high tunnels. A key component of our research will be establishing collaborative arrangements with advanced growers, who face real problems, to conduct replicated on-farm trials. The on-farm research model will ensure an effective extension outcome, guide the project to target real issues, and provide a mechanism to carry out experiments under natural levels of soilborne diseases, particularly southern bacterial wilt (Ralstonia solanacearum), and root knot nematodes (Meloidogyne sp.). Performance of grafted plants in tunnels and in the open field will be compared to that of self-grafted and un-grafted (control) plants. Because grafting technology is a site-specific management tool, scion and rootstocks utilized in on-farm trials will depend on the diseases present and the marketing needs of the grower. Disease resistance and harvest yields will be monitored on-farm, and this experience will provide an avenue of information exchange benefiting both the researchers and growers. The focus will be on rootstocks and cultivars that can be propagated and distributed through growers and seed exchanges. However, commercial (variety protected) cultivars will be included where they offer clear advantages. Educational and other cooperators will be consulted on the most important characteristics of rootstocks, scions, and production systems and some may eventually be involved in distributing and testing rootstocks. Results from on-farm experimentation on resistance to soil diseases will be supported by horticultural trials at the Center for Environmental Farming Systems in Goldsboro, NC. The CEFS site has no known soilborne diseases, but is a superior site to evaluate horticultural performance because of its long history of organic practices. Using commercial and public lines of rootstocks, multiple and single head training systems for grafted plants will be compared under reduced and normal fertility. A factorial design will be implemented where main plots evaluate tunnels vs. open fields, and fertility, graft combination, and training system treatments are subplots. Performance attributes to be investigated at CEFS include: total yield; disease and pest resistance; overall vigor; and nutrient uptake efficiency.

1. Improve grafting, acclimation and transplanting techniques.
2. Select appropriate rootstocks for root-knot nematodes and other soilborne diseases
3. Select appropriate rootstocks for increased nutrient uptake efficiency and other horticulturally valuable
traits, such as fruit quality, earliness, vigor, and resistance to pests.
4. Test training and establishment techniques for grafted rootstocks, including single and multiple head
systems.
5. Compare performance of scions grafted onto resistant rootstocks, self-grafted and non-grafted controls
under realistic conditions of soilborne disease pressure.
6. Compare performance of scions grafted onto resistant rootstocks, self-grafted and non-grafted controls
under optimal growing conditions on an organic research station.
7. Evaluate a grafted rootstock-high tunnel tomato system for feasibility, including a preliminary assessment of
the economics. This system will be compared with open-field production.
8. Identify promising avenues for future research and development.