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p r a c t i c a l w i n e r y & v i n e ya r d M a r c H 2 0 1 4 65 g r a p e g r o w i n g whether fewer membrane dispensers per acre could be effective if each contained more pheromone. In other words, we asked whether saturating the vineyard with pheromone was sufficient, or whether a high density of pheromone emitters was crucial. Effective control was predicted to depend on many phero- mone sources. All of the treatments significantly reduced VMB damage compared with untreated blocks (Table 1). There was really no clear pattern within the phero- mone treatment blocks (rate compared to load or dose). Treatments with the highest density of pheromone membrane dispensers (250 per acre) had 7.22% damage and 9.44% damage at a load of 25 grams and 37.5 grams of active ingredient per acre, respectively. Treatments with 175 dispens- ers per acre had lower damage levels than the higher rate, which is contrary to expec- tations. These plots had 0.56% damage and 1.67% damage in plots with a load of 25 g/acre and 37.5 g/acre, respectively. What is important is that all mating dis- ruption plots had less damage than the control, and in a vineyard that was highly infested in previous years, this represents a remarkable level of insect control. (The grower cooperator reported no additional insecticides were used in the vineyard other than the usual IPM directed applica- tion and that all treatments received the same amount of insecticides. We will be able to design more efficient, effective patterns of pheromone dispersal if we better understand the flight behav- ior of the male mealybug: How far will a male fly to locate a pheromone-emitting female, and how do wind conditions affect flight behavior? VMB was artificially introduced into a pistachio orchard (to avoid having other mealybugs interfere with the study) on the California State University, Fresno, Your success is our prioritY Figure 2. Pheromone membrane dispenser. Table 1. Effect of vine mealybug damage to wine grape clusters at 16% total soluble solids as affected by membrane dispenser hang rate and active ingredient amount per dispenser. Rate * Load ** Dose *** % No Damage % Li le Damage % Damage % Unremarkable 0 0 mg 0.00 g 71.67 21.67 21.67 0.00 125 200 mg 25.00 g 90.00 5.56 5.56 1.11 125 300 mg 37.50 g 87.22 10.56 10.56 1.11 175 143 mg 25.00 g 99.44 0.56 0.56 0.00 175 214 mg 37.50 g 98.33 1.11 1.11 0.00 250 100 mg 25.00 g 92.78 5.00 5.00 0.00 250 150 mg 37.50 g 90.56 7.22 7.22 0.00 * Rate is the number of dispensers per acre. ** Load is the amount of active ingredient per dispenser (in mg per dispenser). *** Dose is the total amount of active ingredient delivered per acre (rate x load).