Gilbert Miller, Clemson Extension area vegetable specialist, taking a look at a grafted watermelon plant. Visible are watermelon vines and gourd vines, a watermelon and a small gourd (which he is holding) which was left on the plant for demonstration purposes. The graft was made when the watermelon and the gourd plants were in the seedling stage.

DATE: 7/18/2006

CONTACT: Gilbert Miller, 803-284-3343, ext. 225; gmllr@clemson.edu

WRITER: Tom Lollis, 803-284-3343, ext. 241; tlollis@clemson.edu

It’s a melon on top, but a gourd underground

BLACKVILLE –An unusual plant greeted visitors at the 2006 Watermelon and Vegetable Field Day July 13 at Clemson University’s Edisto Research and Education Center (REC).

It had both watermelon and gourd vines on top, but it was all gourd underground.

The plant is what results when the top of a watermelon is grafted to a gourd when both are in the seedling stage, according to Gilbert Miller, Extension Service area vegetable specialist at Edisto REC.

“Grafted watermelons are common in Asia, where manpower is plentiful,” he said. “The advantage is that the gourd rootstock is resistant to some of the soil-borne diseases which affect watermelons.”

Richard Hassell, state vegetable Extension specialist from the Coastal REC at Charleston, prepared the grafts which were planted in the demonstration plots at Edisto REC. He demonstrated the technique for a few growers at the end of the day’s program.

“Grafted melons are common in China, Korea and Japan,” he said. “It may be 10-15 years before they catch on in the United States.”

Hassell said that, in addition to providing disease control when chemical control is impossible, grafts hold out the promise of early planting, greater yields and drought tolerance.

“Grafted melons are too expensive to use in this country right now,” said Hassell. “We’re trying to work out the techniques to reduce the cost.” Certain squash varieties also have the disease resistance genes and can be used for grafting with melons.

The field day crowd of about 150 also viewed plots demonstrating the productivity of seven different pollenizers used in seedless watermelon production, watched a demonstration of a forced-air sprayer, and inspected variety trials featuring both mini-melons and medium-sized melons.

Josh Freemen of the University of Florida said that all the pollenizer plants produced about the same yields. He said the keys for producers will be to select pollenizers which do not have vines that compete with the melons intended for market or produce melons which are hard to distinguish from market melons. Seed costs should also be considered when choosing a pollenizer.

Miller said that he is investigating the role of water and nutrient management as possible causes of hollow heart. He is applying large doses of fertilizer through the drip irrigation system every two weeks to see if this causes more hollow heart than small daily applications of fertilizer. Miller is trying a similar water management scheme, comparing weekly applications of water to daily applications.

Following the watermelon program Powell Smith, Clemson Extension vegetable entomologist, took a few vegetable producers to view summer collard plots. Smith has planted sweet alyssum, a low-growing annual with small, white flowers, next to the collards.

“The flowers provide nectar for Diadegma, tiny wasps which lay eggs in diamond back moth larvae, one of the major pests in collards,” he said. “More than half the diamondback larvae which we have collected from the collard plots have been parasitized.”

Smith said that W. P. Rawl & Sons of Lexington County, the state’s largest collard producer, has used sweet alyssum for the past two years to help with pest management.

“It has helped us reduce our pesticide use,” said Howard Rawl, vice president for Rawl & Sons. He said reduced pesticide usage also helps in preventing development of resistance to pesticides in the diamondback moth.

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