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!

Grafted Tomato Production Ends. Analysis Begins.

Last tomato standing. Photo: Kathryn Hamilton

The grafted vines have been pulled. This year felt like a short growing season for tomatoes.  Berkley Pink Tie-Dyes (the scion in our project) have an estimated maturity of 65 – 75 days. The first ripe tomato was picked on July 12, 72 days after the plants went into the ground on May 1.  The last was picked on August 30, from plant 29, which gave its first fruit on May 14.  In all we had 49 (sometimes blisteringly hot) days of tomato picking and data recording.

The data is about to be crunched. Lessons learned will be recorded.

Another component of this project is the development of educational material for both trainers and the public. Already completed are PowerPoint presentations for trainers and the public, and a step-by-step protocol designed to increase grafting success.  Coming up are handouts related to growing (and cooking) tomatoes and a “how to graft” video.

Until next month, when we expect to report on what we’ve learned (including an analysis by the NC Plant Lab), meet the grafting team, who, following the protocol it designed, had an 80% survival rate during our initial experiment.

Sara Smith, Lalitree Darnielle, Ashley Troth, Marty Fisher, Ann Norris and Bev Tisci. Testing the protocol they designed, this team had an 80% grafting success rate.
Photo Kathryn Hamilton

It’s Harvest Time

We collected our first tomato July 12.  As of this writing on August 3, we have collected 360 tomatoes (184 pounds) suitable for donation and 140 (76.3 pounds) of “bad” tomatoes, which have enriched the Briggs Avenue compost pile. The Durham Tech food bank is our first recipient. Cheralyn Berry also delivers food baskets to food-insecure families as part of her work as Agent, Family and Consumer Sciences, and Local Food Coordinator. Anything left goes to the St. Francis of Assisi community garden which delivers it to the NC food bank via Logan’s Garden Center.  

A food basket containing produce from Briggs (including two or our tomatoes). (Left) The haul from July 26. (Right) (Photos: Kathryn Hamilton)

 So far, we’ve had a handful of plants fail due to wilt; one plant fail to thrive; and one that looks like it might have grown from the rootstock. Most plants have leaf spot, but on the whole, they are among the healthiest plants in the garden.

An ungrafted tomato completely wilted by the end of July. (left). This tomato, grafted onto a DRO rootstock, experienced leaf curl and failed to thrive from the beginning (right). So far, it hasn’t given up one piece of fruit. Photo: Mary Knierim
We believe the low-lying plant in front of the vigorous RST graft is rootstock. Photo: Mary Knierim
Pink Berkley Tie-Dye tomatoes in various stages of ripening (top). Below that a tomato from the plant we believe is rootstock.

We have found a few hornworms, but the worst pest throughout the garden this year seems to be Armadillidium vulgare, more commonly known as pill bugs or rollie pollies.

Once we began treating the plants with BT (for the hornworms) and food-grade diatomaceous earth (for the rollie pollies) we started to gain on the depredation.

Going Back to the Funny Flower

Although we can’t be 100% sure, if a tomato did grow from a megabloom (AKA funny flower), this looks like it could be it!

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.

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