By Kim Ellson
Grafting provides a natural method of achieving disease resistance and plant vigor for our favorite vegetable cultivars, said Kim Ellson, a University of Illinois Extension horticulture educator.
“We all have our favorite vegetable varieties. Some love Big Boy tomatoes while others will insist upon Better Boy,” Ellson said. “These are specific cultivars that we are familiar with and that we trust and cherish. Many of us are creatures of habit and we head to our local garden centers with specific cultivars in mind. As a rule, once we have found something we like and that works for us, we do not deviate very much.”
If it has always worked, then what is the problem?
Ellson explained that the problem is a combination of modern-day weather patterns and planting repeatedly in the same place which contributes to disease persistence in the soil.
“Violent rains and extreme temperatures seem to be becoming the norm,” Ellson said. “When we experience heavy rainstorms followed by high temperatures, we have prime conditions for disease.”
With climates becoming increasingly hostile, Ellson said fungal resistance in vegetables is important, and yet it is something that is lacking in old varieties. “Our favorite varieties, whether heirloom or not, tend to be old varieties and do not have the vigor, yield, and resistance of new varieties,” she said.
So why do we cling to them? They have excellent flavor, it is as simple as that, Ellson said. “Present-day cultivars tend to lack the flavor and aroma of their older counterparts,” she added.
This is where grafting comes into play. “Grafting allows us to combine flavor with vigor and disease resistance, thereby allowing us to enjoy the best of both worlds.”
Unlike cross-breeding, with grafting, Ellson said that the parent material and thus the character of the fruit are not altered in any way. “There is no genetic modification involved, and it is a completely natural way to reap the benefits of old and new varieties combined. We’ve all been in that situation where we’ve lost our prized tomatoes, squashes, melons, or cucumbers to fungal diseases. It is an upsetting and demoralizing experience,” Ellson said. “However, we also do not want to give up our favorite varieties!”
Heirloom tomato varieties (Brandywine, Cherokee Purple, Black Krim) and regular tomato cultivars (Big Boy, Early Girl, Super Sweet 100) are all susceptible to fungal diseases and can succumb to early or late blight.
“In the case of grafted plants, a disease-resistant rootstock has been grafted or joined with a desirable fruit or vegetable,” Ellson explained. “The disease-resistant and vigorous plant does not have desirable fruit. By fusing the stems and connecting a top and bottom of two plants, we reap the benefits of resistance, vigor, and desirable fruit.”
Soilborne diseases are persistent once they become established and can re-infect plants for years, Ellson said. “Sadly, diseases are not only restricted to one particular plant. Closely related plants are also susceptible. So an infected tomato could infect peppers, eggplants, potatoes, and tomatillos,” she added.
Grafting protects from certain soilborne disease, yet it cannot eradicate all forms of disease, Ellson cautioned.
“People must not think that grafted plants are simply immune to all diseases. Many common diseases are foliar and these will still require treatment,” she said. “Always check plants regularly to detect any symptoms of disease at an early stage. Effective organic treatments can include products containing copper or sulfur, both fungicides that can be applied either preventatively or curatively.”
Given the advantages of higher yields and soilborne disease resistance, why is everyone not using grafted vegetables?
“It is a combination of price and lack of public awareness,” Ellson said. “Grafted plants are between two to three times more expensive than their regular counterparts, and this puts people off.
“If you are happy with your plants and not experiencing problems, grafted plants may be unnecessary. However, if you do suffer with disease problems or you want higher yields, then grafted plants would be advisable,” she added.
Grafted tomato plants are becoming widespread and are now generally available at garden centers. “Hopefully, as grafted plant sales increase and it becomes more common practice, prices will get lower in time,” she said.
Other vegetables, including cucumbers, squashes, and melons, are also grafted, yet the public is unaware of these plants and their benefits to a large extent.
“Regardless of whether one grows grafted plants or not, there are a few rules everyone should follow to reduce disease occurrence,” Ellson recommended. “Be sure to always water in the morning, water plants at the base, space plants generously, rotate crops, and provide a full-sun location.”