Biology, monitoring and economic impact of blueberry gall midge (Dasineura oxycoccana) in Michigan blueberries

Blueberry gall midge (Dasineura oxycoccana) is a pest of Vaccinium crops, including blueberry and cranberry. This cecidomyiid species has recently become more common in Michigan highbush blueberries, causing damage to young vegetative shoot tips. Feeding by larvae induces growth of lateral branches and may lead to reduced yield. The distribution, phenology, and the effects of damage on bud set and fruit yield were investigated. Widespread monitoring detected this species in 11 counties and over 90% of sampled farms and nurseries. From 2009 to 2011, emergence traps, observational sampling for damage, and shoot tip dissections revealed multiple peaks of activity from May through August with consistent degree day accumulations of key phenological events. Assessment of the economic impact resulting from the damage to vegetative shoots indicated no significant effect of early-season injury but fewer bud numbers on shoots damaged later in the season.