Scorch disease caused by Blueberry scorch virus (BlSV) spreads rapidly and radially from foci of infection. Healthy potted blueberry plants became infected when placed next to diseased field bushes from early May through mid-August. The aphid Fimbriaphis fimbriata, collected from infected field bushes, transmitted BlSV to healthy blueberry plants in controlled tests and was regarded as the most important means by which bushes in commercial fields became infected. The rate of spread in the symp-tomless cv. Stanley appears to be the same as the rate of spread in the cv. Pemberton, which exhibits blight and dieback. Most field bushes showed symptoms during the year following inoculation, but a few did not show symptoms until the second or third year. Many (30 out of 59) cultivars and selections infected with BlSV exhibited severe blighting of flowers and young leaves and dieback of twigs. Three cultivars showed only chlorosis of leaf margins. The virus was also detected in numerous cultivars (26 out of 59) that exhibited no symptoms, and they were considered tolerant of BlSV. The virus had no effect on germination of pollen from several cultivars. BlSV reduced yield in 'Pemberton', with the loss being related to the number of years bushes displayed symptoms. Yield was reduced by more than 85% in the third year of symptom expression. The virus did not significantly reduce the yield of six tolerant cultivars that were infected with the virus but displayed no symptoms.

Root rot caused by Phytophthora fragariae var. fragariae and P. fragariae var. rubi are major concerns in strawberry and raspberry production in the Pacific Northwest. Of lesser importance is black root rot of strawberry, caused by a complex of fungi and nematodes. Soil solarization was evaluated in 1997 in a strawberry planting and in 1998 in a raspberry planting for: (i) enhancing plant health and growth, and (ii) reducing population densities of root-destroying pathogens. Plots were solarized from mid-July to mid-September. Maximum and mean soil temperatures in solarized plots recorded at 10 cm depth were 48 and 33°C in the strawberry plots and 46 and 29°C in the raspberry plots. These temperatures were 7 to 17°C higher than temperatures recorded in nonsolarized plots. Soil collected after solarization was assayed by growing bait plants, cv. Totem strawberry or cv. Qualicum raspberry, at 15°C for 6 weeks in saturated soil to promote infections. Root health and plant growth were evaluated after 6 weeks. Solarization significantly reduced (P < 0.05) root necrosis and increased root weight of bait plants compared to plants grown in soil from nonsolarized plots. Infection of strawberry roots by P. fragariae, Pythium, Rhizoctonia, and Cylindrocarpon spp. was reduced (P < 0.05) by solarization in sampled soil. Disease was reduced in cv. Hood strawberries and Qualicum and Skeena red raspberries planted in solarized field plots. In the second growing season, total number and number of healthy primocanes of Qualicum plants were greater (P < 0.05) in solarized plots compared to nonsolarized plots. Solarization combined with applications of mefenoxam was no more effective in controlling diseases than solarization alone, but better than mefenoxam alone. Skeena plants responded similarly, but the differences were not significant. Red raspberry plants growing in solarized soil yielded more fruit than plants growing in nonsolarized soil in the third year after solarization. Solarization has potential as a component in an integrated pest management program of root diseases in raspberry and strawberry production, particularly within the first 2 years following planting.

Field bindweed (Convolvulus arvensis L.) is widespread in the Pacific Northwest where it is considered a noxious weed. During 2002, collections of a powdery mildew fungus attacking C. arvensis were made from Pierce, Spokane, Whitman, and Yakima counties, WA. Based on morphological features we determined the fungus to be Erysiphe convolvuli. Accepted for publication 22 September 2003. Published 21 October 2003.