Grafting Vegetables for Soil-Borne Disease Resistance


Investigator: Carol Miles, Washington State University Mount Vernon Research Center, Mount Vernon, Washington
Project location: WSU Mount Vernon Research Center and Schrieber and Sons farm, Eltopia, Washington.

Organic tomato, eggplant and watermelon production in Washington is limited by soilborne diseases such as Verticillium wilt. Disease control in organic systems relies on use of resistant varieties, but selection is limited and varieties are often not the ones best suited for the region. Grafting with resistant rootstock is an organically-acceptable technique for disease management and is used throughout Asia, Europe and Canada with excellent results, but has not been explored in the northwest U.S. This project explores the efficacy and costs of grafting tomato, eggplant and watermelon in Washington and explores inexpensive and small-scale appropriate greenhouse grafting techniques.

The objectives of this study are to:

  1. Evaluate in the greenhouse different healing environments for grafted tomato, eggplant and watermelon;
  2. Test grafted tomato, eggplant and watermelon in two Washington organic fields (Mount Vernon and Eltopia), each with high Verticillium wilt pressure;
  3. Evaluate fruit quality of grafted tomato, eggplant, and watermelon;
  4. Calculate costs for vegetable grafting;
  5. Publish information for growers on vegetable grafting methods and techniques.

Field studies of grafted tomato, eggplant and watermelon conducted in 2010 t WSU Mount Vernon NWREC and an on-farm site in Eltopia, WA will be repeated in 2011 at the same locations (grant Year 1). Research design will be a randomized complete block with four replications. Treatments in each study will be the same as in 2010, that is:

  • ‘Cherokee Purple’ heirloom tomato grafted onto ‘Maxifort’ and ‘Beaufort’ rootstocks;
  • ‘Epic’ eggplant grafted onto ‘Beaufort’ and Solanum aethiopicum rootstock;
  • ‘Crisp ‘N’ Sweet’ triploid watermelon grafted on ‘Strong Tosa’ and ‘Emphasis’ rootstocks; and self-grafted and non-grafted control.

Measurable outcomes will include new information on the effectiveness and cost of the vegetable grafting methods being, an expansion of organic crop production options in the area due to effective disease management, providing baseline information for developing production of grafted transplants and rootstock as a new agricultural industry, and dissemination of all this new information to growers.