Grape Flea Beetle - Commercial Fruit Production in Minnesota

DamageGrape flea beetle adult on adamaged bud (T.L. Galvan & E.C.Burkness, U of MN)Damage is caused by adult beetles feeding onprimary buds, which prevents them from developinginto shoots, thus resulting in a decreased yield. Thegreatest economic loss occurs when beetles feed onbuds from “bud swell” until the “first leaf separatesfrom the shoot tip” stages (see Appendix A). Onceshoot growth reaches 7 cm, damage caused by thegrape flea beetle normally does not affect yield.Location of vines can affect the intensity of aninfestation, with vines on the borders of the vineyardand next to wooded areas having higher infestations.In addition, weather can also affect the intensity ofthe damage. Cooler springs will extend the period ofdevelopment when buds are more susceptible to thebeetle feeding, thus increasing the chance ofeconomic loss.Although primary damage is caused by adult fleabeetle to the developing buds, larval damage canalso occur on the foliage and is typically limited toseveral leaves and vines. However, larval damagedoes not usually affect grape quality or yield.Grape flea beetle damage togrape bud (E.C. Burkness & T.L.Galvan, U of MN)ManagementMonitoringGrapes should be sampled during the “bud swell” to the “first-leaf separated from shoottip”stages, which is generally during late April – early May. Sampling should be donetwice per week by checking for damaged buds and flea beetle adults. The currentsuggested threshold is 5% damaged buds.Cultural/Physical ControlRemove debris and leaf litter on the edges of wooded areas located near vineyards toeliminate overwintering sites. In addition, shallow disking the area between grape rowscan also help destroy overwintering pupae.Chemical controlSeveral insecticides provide good control of grape flea beetle, and can be found in theMidwest Small Fruit Pest Management Handbook.