Raspberry Crown Borer, Pennisetia marginata (Harris)

I. Introduction: The sesiid moth can be a severe pest to raspberry and blackberry plantings. Adult moths are yellowjacket mimics. All stages occur on red raspberry, Rubus idaeus L., black raspberry, R. occidentalis L., himalaya blackberry, R. procerus Muell., cutleaf blackberry, R. lacineatus Willd., loganberry, R. loganobaccus Bailey, boysenberry, R. sp. cult., thimbleberry, R. parviflorus Nutt., and salmonberry, R. spectabilis Pursh.

II. Biology: Eggs are laid on the undersides of new leaves, with 2-3 eggs per plant. Eggs incubate 3-10 weeks, beginning to hatch in late July (about the first week of September and continuing until early November in the northern part of its range (Canada)). The young larva spins down to the crown, where it overwinters in a hibernaculum. In the spring it tunnels into the cambium. Cracks develop at this site, from which reddish brown frass is produced in April. During the first summer, the larva feeds at the base of new canes, girdling the plant and causing gall formation. Galls are most evident in October. There is two-year life cycle. In the second summer, the larva ascends into a cane, girdling it a few inches above the soil surface, and causing it to wilt and break. The pupal stage occurs in late June to early August. Moths fly from early to mid July through late September (August through September in the north). Females begin to oviposit beginning on the first day after emergence; the female lives 3-11 days, averaging about 103 eggs.

The following graph shows raspberry crown borer trap captures in experimental traps containing four pheromone loading rates, placed in Westmoreland County in 1997. Males were already flying on the first sampling date (17 July), and were last captured on 26 September. The peak of activity was on 2 August.

IV. Control: Chemical control: In October 2005, EPA approved the use of Capture 2EC as a drench treatment for raspberry crown borer. Apply at either post-harvest (fall) or pre-bloom (spring), as a drench application directed at the crown of plants in a minimum of 200 gal water/A. Greater efficacy has been observed at higher water gallonages up to 400 gal/A, or in an application prior to a significant rainfall event. Do not make a prebloom foliar and prebloom drench application. See supplemental label.

Sevin or malathion may be used as foliar sprays.

Cultural control: Remove all wilted canes in June and July.

V. Other information: See also Arkansas page on raspberry crown borer, and WSU Site for photo.