CONTROL OF POWDERY MILDEW IN VINEYARDS USING SINGLE-APPLICATION VAPOR-ACTION TREATMENTS OF TRIAZOLE FUNGICIDES

The triazole fungicides etaconazole, flusilazole, myclobutanil, pencon azole, triadimefon, and triadimenol were applied as formulated product s to cheesecloth wicks. The treated wicks, containing fungicide at the rate of 0.24.0 g a.i. per vine, were hung beneath the fruiting zone i n the grapevine trellis during the period between bloom and 2 wk after shatter. Although no further fungicide treatments were applied for th e growing season, fruit in treated vines in the most effective treatme nts remained free of powdery mildew until harvest. Control of powdery mildew was observed in a zone having a radius of approximately 45 cm f rom the treated cheesecloth. Control of powdery mildew equivalent or s uperior to that obtained with cheesecloth wicks was obtained when cott on rope or string was treated with penconazole and deployed as above. Less effective control was obtained when two cellulose sponges per vin e were treated with penconazole and similarly deployed.