Damaging wine grape pest confirmed in Mesa County

Officials with the Colorado Department of Agriculture and Colorado State University are working with a vineyard owner to contain and eradicate the pest even as surveying continues to assess the scope of the infestation.

“Hopefully, we’ve caught this quickly enough to protect Colorado’s grape crop,” said Laura Pottorff, a nursery and phytosanitary program manager with the Colorado Department of Agriculture.

Phylloxera, an aphid-like insect that feeds on grapevine roots, was positively identified by entomologists with the U.S. Department of Agriculture Agricultural Research Service.

Phylloxera can take multiple forms during its life cycle. The most serious and damaging form, which was found in Mesa County, feeds on grapevine roots, in turn disrupting water and nutrient flow and damaging plants. Infested grapes appear weakened and stunted with leaves lighter in color that look as though they’re suffering from nutrient deficiency.

Nearly 75 percent of wine grape acreage in Colorado is located in the Grand Valley American Viticultural Area located along the Colorado River between Palisade and Grand Junction, said Doug Caskey, executive director of the Colorado Wine Industry Development Board.

The Grand Valley AVA is known for its unique growing environment and high elevation that produce world-class quality wine grapes, Caskey said.

About 150 grape growers tend to a total of 1,000 acres of vineyards in Colorado. More than 140 commercial wineries produced a total of 166,000 cases of wine worth a collective $33 million during the 2016 fiscal year.

The Colorado Department of Agriculture has urged vineyard operators to contact their nursery suppliers to find out if any procedures are in place to identify and stop the spread of phylloxera. Growers also have been asked o take precautions:

Watch plants for stunting and other symptoms that mimic nutritional deficiencies and sample roots for the presence of phylloxera.

Wash and sanitize cultivation and harvesting equipment between fields.

Request that grape nursery stock be dipped in hot water prior to shipment.

Examine all new nursery stock prior to planting or schedule an inspection by CDA staff.

Consider the use of root-grafted nursery stock.