Grape Phylloxera detected in Colorado’s Grand Valley
U.S. Department of Agriculture’s Agricultural Research Service entomologists positively identified grapevine phylloxera (Daktulosphaira vitifoliae) on Vitis vinifera grapevines in the Grand Valley American Viticultural Area (AVA), which is a federally designated grape production area in western Colorado.
Phylloxera is an aphid-like insect that feeds aggressively on grape roots.
In its full life cycle, phylloxera can take multiple forms. The most serious and damaging form, which was recently discovered in Mesa county, feeds on roots of grape plants. It can damage the plant by disrupting water and nutrient flow.
Initially, infested plants appear weakened, stunted, and with leaves lighter in color which may look like they are suffering from a nutrient deficiency. In addition, phylloxera can live out another stage of its life on grapevine leaves.
This less serious form feeds on leaves that causes leaf galls to develop, but generally not on V. vinifera. ■