Tomato Grafting Project

Welcome to the page for  Durham County’s Extension Master Gardener Tomato Grafting project.

Tomato grafting is a great way for gardeners to grow their favorite tomatoes on rootstock that is resistant to the soil-borne diseases

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Photo Credit: Marty Fisher

that plague many gardens. When grafting tomatoes, the preferred tomato cultivar (scion) is clipped to a disease-resistant root stock then left undisturbed. By providing the right conditions, the two vascular systems grow together, producing a plant with desirable fruit and strong, resilient roots.

Over the last several months, Durham County Extension Master Gardeners have been working to develop information that will help tomato lovers throughout the Triangle succeed in grafting their favorite tomatoes onto disease-resistant root stock.

Check back here frequently for news about the project along with updated listings of information and events. Our newest entries are on top!

What’s With the Funny Flower?

An early inspection revealed what appeared to be two different flowers among the plants: the normal blossom and one that was over-sized and misshapen. A puzzle, indeed, since all scions are the same cultivar and should have similar-looking flowers. Grafting team member Sara Smith researched and found the answer.

Typical blossom, left. Photo: Kathryn Hamilton Megabloom blossom, right. Photo: Sara Smith

“The big, misshapen tomato blossom that looks like three or four fused together is called a megabloom. It is caused by a disturbance to the meristem while the flower is developing and can be caused by one of several things including insect damage, chemicals, cold, even too much fertilizer.” She also noted that the tomato she grafted in the fall, as part of the tomato grafting protocol and which over-wintered in the cool section of her hoop house, also had a megabloom.

Early Days in The Tomato Patch

The tomatoes did not have the easiest start. One week after they went into the patch, the night-time temperature uncharacteristically fell to 35° F. Quickly covered, they made it through the night. Initially almost all the tomatoes exhibited some leaf spot and chlorosis. After their third week, every single tomato showed signs of improvement with the earlier weaknesses largely confined to the oldest leaves.

Number 9 with clip. Number 3 in recovery mode. Number 14 failing. All photos: Kathryn Hamilton

While we will appreciate every tomato that survives and thrives, two have found their way into our hearts: our smallest tomato, #9, an RST graft who came into the patch still wearing his grafting clip, and our weakest tomato, #3, a DRO graft,  who was all but hanging on for dear life after the first week.  Alas in week 4, we lost tomato number 14, clearly a failure of the graft. The Tomatoes Are In!

Number 14: Tomato Graft Failure. Photo: Kathryn Hamilton

The Tomatoes Are In!

Forty tomatoes, a combination of grafted and ungrafted, were planted at Briggs Avenue Community Garden on May 1. Pink Berkley Tie Dye was chosen as the “scion” or top. For the sake of comparison, 12 each of two different root stocks, RST 04-105 and DRO 141TX, were used. Both were chosen for their resistance to wilt and verticillium, common tomato diseases in the Piedmont. Eighteen ungrafted tomatoes were also planted so we could compare performance of grafted vs non-grafted.  To replicate what is often typical in a home garden, the 4’ X 10’ plots were densely planted with two rows of four tomatoes. There are 2.5’ between tomatoes and 2’ between rows.  They will “grow up” on stakes. The tomatoes are being monitored three times a week for leaf health and wilt. Ultimately the poundage and quantity of fruit will also be measured. Produce will be donated.

Tomatoes on staking day about a month after planting. Photo Credit: Kathryn Hamilton