High Country growers attend Extension’s Cucurbit Workshop

Dylan Lightfoot Staff Writer

September 9, 2013

Cucurbit is a funny-sounding word.

They’re funny-looking, too. Behold the peanut pumpkin, the turban squash, or any “decorative gourd.”

But cucurbits — collectively the 960-odd species of the plant family Cucurbitaceae — are serious business at the Upper Mountain Research Station, where dozens of winter squash varieties are being tested for viability and marketability in an effort to help local growers get the most out of their crop.

Approximately 60 growers attended the N.C. Cooperative Extension’s four-hour Squash and Cucurbit Workshop at UMRS Thursday, where they learned from specialists the details of cucurbit crop management, disease and pest control.

Yield summaries are being compiled on winter squash grown at UMRS. Varieties of pumpkin, acorn and butternut squash and others are being rated for consumer and culinary appeal based on metrics of flavor, flesh thickness and consistency of size shape and color.

This data will be available next year, according to extension staff.

By far the biggest problem facing commercial cucurbit growers in the Southeast are the leaf diseases downy mildew and powdery mildew. Caused by microbial parasites, mildews can cause severe defoliation of plants, resulting in yield loss.

According to Assistant Professor Lina Quesada of the N.C. State University Department of Pathology, organic growers have the most trouble with mildews, as there are not a lot of options for organic controls. Mildew spores can last in the soil for as long as 20 years, making crop rotation an ineffective strategy.

And, while selection of disease-resistant varieties is effective to a degree, often the most resistant varieties have the least appealing flavor and appearance. “(With cucumbers), disease resistance is linked to poor taste and ugliness,” Quesada said.

As a result, conscientious application of a handful of effective fungicides — Presidio, Ranman, Previcur Flex — is recommended. Using these chemicals as directed is crucial, Quesada said, because mildews develop resistances to them, and product misuse can create resistant strains that quickly propagate across large areas.

To forecast the arrival of mildews, test farms in the Southeast region have established an array of “sentinel plots,” small squash gardens planted specifically to register the appearance of airborne mildews in a given area. The progress of the pathogens through a region is thus charted, and fungicide applications can be timed for maximum effectiveness and minimal environmental impact.

Insects pose a double threat to cucurbits. According to N.C. State Entomologist Jim Walgenbach, feeding cucumber beetles and squash bugs can infect plants with bacterial wilt, and aphids can cause mosaic viruses in cucumbers and watermelons. Insecticides are not very effective against these transmissions.

A suggested organic control for pests is silver-painted plastic mulch, which confuses insects with reflected light. Effective pesticide programs include spraying of high-pressure oils, and water-based products applied through drip irrigation systems.