Vine decline has impacted South Texas melon crops for years. This disease strikes late in the growing season, at a time when most farmers are contemplating harvest. But just as the cantaloupes begin to ripen, plants and profits wither and die.

Also known as sudden wilt, the disease is caused by a soil-borne fungus called Monosporascus cannonballus. It damages root systems, leaving them unable to supply the water and nutrients melons need to develop and survive. Honeydew crops can also be affected.

Other melon-growing regions areas, including Israel, also suffer from the same disease. Until now, growers here have had some success by fumigating soils with methyl-bromide. But this chemical is not environmentally friendly and will soon be banned from use worldwide.

Efforts to breed resistant melon varieties and find alternative fumigants are ongoing, but those solutions will take time.

Two Texas Agricultural Experiment Station scientists in Weslaco, Dr. John Jifon, a vegetable stress physiologist, and Dr. Kevin Crosby, a vegetable breeder, think grafting could provide an alternative method of managing the disease.

By mechanically grafting the commercial cantaloupe variety (scion) onto a more vigorous and resistant root system from a hybrid squash, the two scientists hope to develop a plant that will withstand the root infection and subsequent drought stress.

"Some of these rootstocks are capable of rapidly regenerating roots to replace those damaged by the fungus," Jifon said, "and we think this is a mechanism that can help susceptible commercial varieties survive infection."
After germinating them in seedling flats in a greenhouse, Jifon began grafting rootstocks from squashes and inbred melons in Crosby's breeding program with Primo, the most widely-used commercial cantaloupe variety in South Texas.

"We will allow the grafted plants to heal for two or three weeks in a temperature- and humidity-controlled growth chamber," Jifon said. "Then some of the seedlings will be transplanted to field plots for evaluation while others will be inoculated with the fungus in the greenhouse for detailed physiological assessments."

Grafting melons onto different rootstocks is not a novel approach, Crosby said. The practice is often used in Japan, Korea, and the Mediterranean region.

"The Israelis have also had some luck with grafting melons," he said, "but they grow different varieties than we do, so we need to test our commercial cantaloupe varieties with many different rootstocks to see which perform best."

If Jifon's tests are successful, grafting the thousands of melon plants in commercial production would be a tedious and costly proposition, he said. But growers would see other benefits.

"It will reduce the amount of fungicides a grower has to purchase and use," Jifon said. "It's a more environmentally friendly way to grow melons and it will offer a solution until resistant varieties can be developed, which could take years."

Jifon's experiments at the Texas A&M University System Agricultural Research and Extension Center at Weslaco are part of a collaborative effort funded through the Texas Department of Agriculture's Texas-Israeli Exchange Fund Board in cooperation with the Binational Agricultural Research and Development Fund (BARD).

In addition to Jifon and Crosby, Dr. Daniel Leskovar, a plant physiologist with the Experiment Station in Uvalde, and a group of scientists in Israel are also working on the project.