Pumpkin producers in Ohio probably had to battle the scariest year yet for the squash-bug-vectored disease yellow vine this season.
Yellow vine disease has been in Ohio since 2003, but only sporadically, says Celeste Welty, an Ohio State University entomologist in Wooster. This year, however, was more severe.
"Ohio State specialists believe this may be the worst year yet for yellow vine," Welty says. "Because of the nature of how it's spread and the damage it does to the crops, there's concern that this has the potential to be a serious disease."
Research suggests that squash bugs carrying the pathogen Serratia transmit it to the plant through feeding, according to a university news release. Once infected, the plant exhibits symptoms of yellowing and wilting foliage and stem discoloration.
The plants collapse before fruit maturity, and death can follow. If the plant lives, it will not produce fruit.
Yellow vine infects a number of cucurbits, including squash, pumpkin and melon. Cucumbers are not affected.
Welty collected samples of pumpkin and squash plants at Waterman Farm that exhibited symptoms of yellow vine. The samples were tested by university plant pathologist Sally Miller and her colleagues.
Half of the samples were positive for the disease. Researchers hope to have the test available to producers next year.
"Diagnosing the disease is tricky because the yellowing is similar to other diseases and symptoms don't show up until about 28 days after infection," Welty says. "The key to managing the disease is controlling the squash bug."
Squash bug adults overwinter and emerge in June, laying eggs on the leaf underside. The eggs hatch about two weeks later, with nymphs feeding on the plant leaves and stems for up to a month.
Squash bugs also will feed on the fruit before harvest.
Ways of controlling the squash bug include rotating in non-cucurbit crops or promoting the crop's early growth, using biological controls such as parasitic flies and wasps and chemical control with approved insecticides.
For more information on yellow vine or other cucurbit diseases, log on to vegnet.osu.edu.