Cane fruit-Rose stem girdler

Agrilus cuprescens

Rose stem girdler is a damaging, small coppery metallic beetle (family Buprestidae) pest of cane fruit, increasingly being reported by growers throughout the Willamette Valley region of western Oregon and in southwest Washington. Infestations can reduce yield or kill canes. Canes with feeding damage are more susceptible to winter injury. Economic loss, particularly in blackberry cultivars with softer stems, has been reported. In addition to raspberry and blackberry, its host range includes wild Rosa and Rubus species. Adult beetles emerge from canes in late April - June. Prior to egg-laying adults must feed on leaves, resulting in a tattered appearance. Once reproductively mature, females lay their eggs generally on the basal 1/3 of canes. Eggs hatch within two weeks and flat-headed larvae bore directly beneath their eggshells into the canes. Larvae are cream-colored and feed just below the bark of the primocanes. During June, first and second instar larvae feed within the vascular tissue resulting in a characteristic spiral gall-like swelling, particularly apparent on first year soft and tender canes. Other symptoms include presence of elliptical emergence holes, wilted top growth appearing in June and July, and weakened canes which easily snap, particularly canes weighted by ripening berries. By mid-July third instar larvae move into the cane pith, where they remain until the following year when they pupate late March to early April and adults bore out of the canes.

Management-chemical control: HOME and COMMERCIAL USE

Continuous pruning and destroying of infested canes can help reduce field populations but should be supplemented with chemical controls if infestations are heavy. There are no insecticides labeled for control but applications of insecticides that are registered for use on caneberries that are relatively safe for pollinators, may provide some measure of control. Chemical management is targeted at the adult beetles to prevent egg-laying. Weekly applications should be applied as full cover sprays, including the basal area of the canes, beginning in mid- to late-April and continued while adults are present. Follow all pollinator guidelines that may appear on the pesticide labels.