Tuesday, October 28, 2008

Tomato Grafting Workshop

Yesterday I took part in a Tomato Grafting Workshop** with Tom Elmore from Thatchmore Farms and Dr. Jeanine Davis from NCSU (both pictured below right). It was a great afternoon! About 20 people were in attendance at Reems Creek Nursery in Weaverville to learn about the process and applicability of grafting in vegetables.

The reasons for grafting vegetables are similar to the reasons why fruit trees and other woody perennials are grafted: for disease resistance and/or increased vigor. Tom explained that there are rootstock available from seed companies that were developed for grafting purposes with increased vigor and resistance to multiple diseases such as bacterial wilt, Fusarium wilt, Verticillium wilt and nematodes. We also discussed that it is important to get positive identification of a disease problem in order to properly chose your rootstock.

Tom shared a video from the University of Vermont that demonstrated the grafting process as well as different grafting techniques. Tom also discussed his experience with grafting, explaining his success with grafting vigorous and healthy plants in his greenhouse after many years in tomato production. He explained that the grafted plants reminded him of the way his tomatoes used to look. Tom is planning to plant grafted tomatoes in the field next season, as well as in his greenhouse.

Dr. Davis and I discussed some different aspects of grafting in vegetables, including why you would want to graft and the research that is being currently being done to address this topic. Dr. Davis talked about the applicability of grafting heirloom tomatoes onto disease resistant rootstocks because of the lack of genetic disease resistance available in heirloom varieties. I talked a little about the history of grafting and the applicability of grafting for cucurbits (left, grafted cucumber). Grafting of watermelon on gourd rootstock for the control of Fusarium wilt has been taking place since the 1920s in Japan and Korea!

After a great discussion with the audience, Tom graced us with a performance of his tomato grafting technique (right). We joked that if this organic farming thing doesn't take off then Tom has a future as a surgeon!

Finally, it was our turn to try. I was lucky to find a participant who was nice enough to act as a hand model/demonstrator of the grafting technique.
Below is a series of pictures of the grafting. First, the stem of the rootstock and scion (the top of the plant- this is the one whose fruit you are desiring) are sliced at a 45 degree angle. Next, a clip is placed on the rootstock. Then, the scion is slipped into the clip gently. The goal here is to align the vascular system of the rootstock and scion as seamlessly as possible trying to ensure that the graft will take. Finally, you have a finished product!

It is important to care for your grafted plants with great attention. Think about it, the scion has been separated from its root system! The plants should be kept in a low light and high humidity setting. This will slow the transpiration of the plant and help the scion from becoming water stressed during this fragile period. Eventually, the graft union will heal and gradually more and more light and less humidity will be added. After the plants harden off, they are ready to be transplanted into the ground or greenhouse. The grafting process adds about a week to the transplant system- so plan accordingly!

Supplies for grafting, including clips and rootstock and heirloom tomato seeds can be purchased through Johnny's Selected Seeds.

To learn more about grafting:
**This workshop was part of the 2008 Farmer Education Series put together by the Organic Growers School.**