626 Field Assessment of Combined Bud Damage on Floricanes of Red Raspberry Caused by Cold Injury, Clay Colored Weevil, and Spur Blight Disease

Abstract

A field experiment was conducted in Lynden, Wash., to assess the combined bud damage to raspberry caused by cold injury, clay colored weevil (CCW) and spur blight disease last year. The CCW treatments included 3 and 6 weeks of continuous feedings and a minimal feeding in a nearby planting with no CCW infestation. Two other sets of field experiments evaluated cold injury to raspberry alone. Cold injury caused significant bud damage and moderate yield losses last winter. The large compensatory ability of raspberry makes yield loss due to cold injury alone insignificant in most years. Cold injury reduced berry yield mainly through a drop in lateral number/cane due to bud damage and cane die back. The combined damage of cold injury with infestations of CCW and spur blight, to the buds and fruit yield were devastating, and 60% bud damage and 61% yield loss were recorded. The combined damage was well over the compensatory ability of raspberry, and resulted in not only lower lateral number/cane, but also lower fruit number/lateral and fruit weight. The bud damage by CCW in the spring left little time for the secondary laterals to initiate flowers. An integrated pest management system is highly recommended to avoid the cumulative damage to the buds and has special importance in areas, where cold injury occurs frequently. Bud damage counted as cold injury was higher in the control plots (18%) than in the weevil-infested plots (6% to 9%). This was likely due to undercount of some cold damaged buds in the infested plots, which also suffered CCW feeding. All plots had similar levels of spur blight bud infection numbering from low to mid-teens. Spur blight-infected buds are often capable of producing normal fruiting laterals.