CSANR Grants Database

Title:

Vegetable grafting for Verticillium dahliae resistance

Tomato, eggplant, and watermelon can be significantly impacted by Verticillium wilt, a soil-borne disease common throughout Washington. Verticillium microsclerotia are known to persist in soil for over 13 years. Symptoms impact plants later in development after most production costs have been incurred, resulting in a 25-100% crop loss in some years even when ground has been fumigated prior to planting. Grafting vegetable crops onto resistant rootstock is a cultural control method that provides an organic and sustainable alternative to soil fumigation. Grafting has been used successfully in Asia for nearly 100 years, but is only now being adopted in the U.S. Grafting adds to production costs but is cost effective where disease pressure is high, such as in high tunnels and hoophouses, when high-value crops are often grown with minimal crop rotation. In Washington, both conventional and organic growers have expressed interest in grafting as an IPM strategy. This project examined the effects of grafting on disease resistance of heirloom tomato, eggplant, and watermelon in open-field production in Washington via on-farm and on-station trials. This project addressed the BIOAg priority area No. 1 by investigating a biologically intensive approach to disease management.

To increase grafting success, a healing chamber study was set-up and we found that an effective design involves a height of approximately 0.6 m covered with plastic and shade cloth to maintain 85-95% humidity, and temperatures maintained between 20-25 oC. In 2010 and 2011, grafting Cherokee Purple tomato with Maxifort or Beaufort rootstock did not affect total or marketable fruit number and weight. There were no Verticilium wilt symptoms observed in tomato in this study either year. In contrast, grafting Epic eggplant onto ‘Beaufort’ rootstock resulted in more vigorous plants with generally higher yields and lower severity of Verticillium wilt, even though ‘Beaufort’ rootstock was not found to be resistant to V. dahliae. Eggplant grafted onto Solanum aethiopicum had lower vigor and generally higher Verticillium wilt severity than other treatments, thus this rootstock is not recommended for grafting eggplant in thePacific Northwest. Crisp’n Sweet watermelon grafted onto ‘Emphasis’ and ‘Strong Tosa’ rootstock had significantly less Verticillium wilt severity than non-grafted and self-grafted watermelon, however there were no differences in total and marketable fruit number and weight of fruit. Plant damage from high winds in theColumbiaBasin in 2011 and cool 2010 and 2011 growing seasons in westernWashington resulted in inconclusive harvest data for this study. Further research is needed to better understand the effect of grafting on watermelon yield and Verticillium wilt severity in thePacific Northwest.

1. Johnson, S. and C. A. Miles. 2011. Effect of healing chamber design on the survival of grafted eggplant, watermelon, and tomato. HortTechnology, 21(6):752-758.
2. Johnson, S.J., C.A. Miles, P.A. Kreider, and J. Roozen. 2011. Effect of healing chamber design on the survival of grafted eggplant, tomato, and watermelon. 2011 International Plant Propagators' Society North American Western Region Annual Meeting, Sacramento, CA, Sept. 21-24, Vol. 61: in press.
3. Johnson, S., and C. Miles. 2011. The effect of humidity in healing chamber environments on the survival of grafted eggplant, watermelon, and tomato. HortScience 46(10):S224.
4. Johnson, S., C. Miles, P. Kreider, and J. Roozen. 2011. Vegetable grafting: eggplants and tomato. Washington State University Extension publication FS052E.
5. Johnson, S., C. Miles, P. Kreider, and J. Roozen. 2011. Vegetable grafting: the healing chamber. Washington State University Extension publication FS051E.
6. Miles, C., S. Johnson, and A. Foren. 2011. Grafting Vegetables. Web page developed and updated regularly. http://vegetables.wsu.edu/graftingVegetables.html
7. Johnson, S., C. Miles, P. Kreider, J. Roozen, J. King, and G. Sterrett. 2011. History of Vegetable Grafting, narrated PowerPoint presentation http://breeze.wsu.edu/historyofgrafting/
8. Johnson, S., C. Miles, P. Kreider, J. Roozen, J. King, and G. Sterrett. 2011. Grafting Healing Chamber, narrated PowerPoint presentation. http://breeze.wsu.edu/healingchamber/
9. Johnson, S., C. Miles, P. Kreider, J. Roozen, J. King, and G. Sterrett. 2011. How to Graft Tomatoes and Eggplant, narrated PowerPoint presentation http://breeze.wsu.edu/howtograft/
10. Johnson, S., C. Miles, P. Kreider, J. Roozen, J. King, and G. Sterrett. 2011. Transplanting Grafted Plants to the Field, narrated PowerPoint presentation http://breeze.wsu.edu/transplantinggrafts/
11. Johnson, S.J., C.A. Miles, P.A. Kreider, and J. Roozen. 2010. Grafting vegetables for resistance to soil-borne diseases: an organic alternative to soil fumigants. 2010 International Plant Propagators' Society North American Western Region Annual Meeting, Bellingham, WA, Sept. 9-11.

WSU Dept. Hort and LA $ 8,167

Washington State Committee on Pesticide Registration 1020 $14,844, 2011 $15,059

OSU – George Clough and growers 2010 $7,866

Northwest Agricultural Research Foundation 2010 $4,913, 2011 $5,030

In-kind (on farm plot maintenance, crop receipts etc.) 2010 $6,000, 2011 $6,750

Organic Farming Research Foundation 2011 $12,984