An insect that is endangering Mesa County vineyards has gotten the attention of the Colorado State University extension office in Montezuma County.
The grape phylloxera, a tiny aphid-like insect that feeds on the roots of grape vines, had been found in Mesa County’s Grand Valley wine region, the Associated Press reported. Native to the northeastern U.S., phylloxera is one of the world’s most destructive vineyard pests. Until the recent report, western Colorado was one of the few wine-producing regions in the world where phylloxera infestations had not been confirmed.
Tom Hooten, director of the Colorado State University extension office in Montezuma County, said that if phylloxera spread to the Cortez area, it could be very damaging to local wine producers like the Guy Drew and Sutcliffe vineyards.
“It has not been confirmed here, and we’re hoping it isn’t,” Hooten said. “But we should definitely keep an eye out.”
Grape phylloxera comes in two different forms. The aerial form, which feeds on the leaves of grape plants, doesn’t usually have a significant effect on the crop’s yield or quality. But the kind recently found in Mesa County, which feeds on the roots, is very damaging and can easily destroy a vineyard. Right now CSU and the Department of Agriculture are conducting sample studies to find out how widespread it is.
Susan Carter, horticulture agent at the CSU Tri River Area extension in Grand Junction, said that although confirmed cases of phylloxera were only recently spotted in the area, it could have been feeding on grape vines for a long time.
“Usually you don’t know you have it until the plants start to decline,” she said.
The root-feeding insects are so small that they can barely be seen without a microscope. An infestation can be spotted by its symptoms – typically a decline in plant vigor, early yellowing of leaves and root distortion – but by the time these symptoms are visible, according to CSU entomologist Bob Hammon, “the vineyard is doomed.” The only long-term way to get rid of a phylloxera infestation is to replant the vineyard.
As a result, Carter and Hammon said it’s important for grape producers to focus on protecting their crops from infestation. Certain grape varieties are resistant to phylloxera, although most of those used for high-quality wine production are not. Carter said the best way to avoid phylloxera is to be “hypersensitive to cleanliness.” She recommended producers clean all their equipment regularly and avoid carrying tools or plant material of any kind between rows of grapes. Hot water treatments can also protect bare root plants from phylloxera.
In a press release issued after the phylloxera was discovered, Hammon said all Colorado grape producers should start inspecting vines for aphids before planting them, especially when they’ve been ordered from other states, and should carefully monitor all movement between vineyards.
“Other areas that have been invaded with phylloxera have survived, but it has taken a change in the way growers manage their vineyards,” Hammon said. “There is no reason to suspect that western Colorado vineyards will be any different.”