Grafting to sturdy root and main stem stock also improved the yields of the heirloom tomato varieties where there was not disease pressure, which makes growing unique and interesting tomatoes — even by organic methods — considerably more economically productive for small market growers, and allows home gardeners a wider choice of tomato selections.

One company, Mighty ‘Mato has taken grafting to a new level for both organic and commercial growers.

Indiana-based Mighty ‘Mato is the first national brand featuring grafted tomatoes and grafted vegetables. Worldwide, over 1 billion vegetables are grafted annually, primarily for commercial production.

“My advice to commercial vegetable growers, who are interested in looking at grafting, is to move forward with trepidation.

“We don’t have enough testing done to know a lot about how one rootstock will perform under different production and environmental conditions,” Freeman says.

All rootstocks are not created equal. Some claim to have great resistance to bacterial wilt, for example, but when he put them in field tests in Eastern Virginia they failed. “We’re just not in a position to have looked at enough rootstocks to know which is going to work over a wide production area,” he adds.

Freeman says researchers know even less about vigor than about disease packages on various rootstocks.

“If you are growing in a high tunnel versus an open field, you are looking for different things and the same rootstock will likely have different results from one growing system to the other.

“In a high tunnel situation, growers are usually looking for 10-12 harvests and plant vigor over a long growing season is important.”

“In an open field production, uniformity may be more important because the grower is harvesting fewer times.”

Louws and Freeman agree that the key to including grafting into commercial operations is to know the problem.

“If a grower knows for sure there is a certain disease problem in a field of vegetables, most likely we can solve his or her problem with grafted plants.

“Again, whether fixing the problem means fixing profitability depends on a lot of things and successful grafting of plants may make the profitability problem worse, Freeman says.

“Grafting is already a routine part of several small, mostly organic vegetable producers in North Carolina, so we know it can work in some operations.

“When we go to commercial production, there is a whole new set of challenges, many of which are being addressed by the multi-state, multi-year grafting project that is currently under way in North Carolina and a number of other cooperating states,” Louws adds.

rroberrson@farmpress.com