BLACKVILLE — Fall has finally arrived and with it come the fall vegetables so many people love.

Clemson University specialists are engaged in pumpkin variety trial with New Zealand company.

Among topics discussed, attendees at the 2016 Clemson Fall Vegetable Field Day learned about diseases and other culprits that can attack fall vegetables such as pumpkins.
Image Credit: Denise Attaway / Clemson University

To help South Carolina residents grow the best fall produce, faculty and staff at the Clemson Edisto Research and Education Center (REC) shared valuable knowledge during its annual Fall Vegetable Field Day. Several fall produce crops were covered during the field day, including pumpkins, fall watermelons and sweet potatoes. Learning how deal with diseases and viruses that affect these seasonal favorites is important.

Downy Mildew is one of the most common cucurbit (gourd) diseases in the fall,” said Tony Keinath, a Clemson plant pathologist at the Coastal REC. “The warm days and cool nights lead to long periods of dew, which is very favorable for development of the water mold that causes Downy Mildew.”

Fungicides, including Chlorothalonil or Mancozeb, are used to control Downy Mildew on cucurbits. These should be applied before Downy Mildew is present. Once Downy Mildew is present, growers should use fungicides such as, Gavel, Ranman and Orondis Ultra, which are  specific for Downy Mildew. Growers also can register for the Cucurbit Downy Mildew Alert System at

Powdery Mildew and Fusarium Wilt are two other diseases to watch out for in cucurbits. Planting resistant varieties is the best defense against these two diseases.

Mosaic viruses can bring another set of problems for fall cucurbit crops, Keinath said. These viruses are transmitted from plant to plant by aphids, which can probe the leaves and infect plants. The three main viruses are Papaya Ring Spot Virus, Watermelon Mosaic Virus and the Zucchini Yellow Mosaic Virus.

Insecticides are not effective in controlling mosaic viruses, Keinath said. The best control for viruses is to plant resistant cultivars.

In addition to learning about diseases and viruses attacking cucurbits, attendees also learned about a pumpkin variety trial with a New Zealand company Gilbert Miller, an Extension horticulturist, is leading. In addition, attendees were given an update on a sweet potato study being done by Miller and Brian Ward, a research specialist, together with Phil Wadl of the United States Department of Agriculture. The sweet potato study includes studying the Sweet Potato Leaf Curl Virus and its impact on yield, as well as developing varieties that are resistant to soil pests, Miller said.

Other information shared during the field day included a discussion on grafted rootstock tolerance to root knot nematodes by Miller and Ben Hinson of TriEst Ag Group. Powell Smith, an extension entomologist, talked about spider mites in watermelons. A presentation also was given in regard to the Nachurs Nutrient Applications.