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64 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 g r a p e g r o w i n g O ne of the most damaging grape- vine pests in the United States is the invasive vine mealybug (VMB), a vector (carrier) of grapevine leafroll-associated viruses (GRLaV). While a variety of chemical and biolog- ical controls have been developed to tar- get the VMB, none have been capable, on their own, of effectively limiting the spread of GRLaV. This work was undertaken to see whether mating disruption— a strategy of using pheromones to radically decrease VMB mating success in the vineyard— on its own and in combination with insecticides, offers a better way of controlling VMB in California's Lodi-Interior vineyards. Mating disruption relies on the peculiar biology of the VMB: Winged adult males locate and fly to wingless adult females to mate by virtue of sex pheromones that the females emit. When the local environ- ment is overloaded with a synthetic ver- sion of the pheromone (Lavandulyl Senecioate), the synthetic signal masks the female-associated one, males are unable to efficiently locate females, and mating is disrupted. Field trials in 2011 and 2012 in Napa County, Calif., demonstrated that mating disruption reduces GRLaV-associated grapevine damage. The number of com- mercially available pheromone dispens- ers (CheckMate VMB-XL, Suterra LLC) needed throughout the vineyard (one placed every two to three vines [250 per acre]) made this strategy expensive, time- consuming and therefore limiting imple- mentation in the vineyards. We attempted to devise how to saturate a vineyard with an effective amount of pheromone in less expensive and labor-intensive ways. Puffers are aerosol spray cans con- trolled by programmable chips and com- bined in a brown plastic housing that resembles a small bird box (Figure 1). On successful applications against moth- pests affecting a variety of crops, they are applied at a density of only 0.5 to two per acre for effective performance. Their efficacy was tested against VMB in a 56-acre vineyard known to have VMB problems in Denair, Calif. Treat- ment blocks were hung with two puffers per acre — each on a 6-foot stake above the canopy— plus a perimeter of conven- tional dispensers that, in total, emitted about one-eighth as much pheromone as the puffers. Even though both the treatment and control blocks received the same delayed dormant application of chlorpyrifos and a post-harvest application of spirotetra- mat (Movento, Bayer CropScience), pher- omone-treated blocks were less severely affected by VMB damage. Fewer mealy- bug males were caught in pheromone- baited traps in treated blocks than in untreated blocks. VMB cycle through five to seven gen- erations per year, so the number of males caught in traps primarily represented the males' ability to home in on sources of pheromones We assume that if they can- not effectively locate traps, they can also not effectively locate females — rather than an absolute reduction in VMB num- ber from week to week as the traps were collected. We also asked more specifically how many membrane dispensers and how much active ingredient per membrane dispenser are needed to effectively sup- press VMB mating (Figure 2). Dispenser coverage and active ingredient contents for VMB suppression in vineyards had been based on patterns found effective against other pests; no one has deter- mined the minimum effective coverage specifically for the VMB. Three-year field trials (2010 –12) in San Luis Obispo County, Calif., demonstrated that commercial dispeners (each contain- ing 150 mg pheromone) placed at either the customary 250 dispensers per acre or at 188 dispensers per acre significantly reduced the number of VMB males caught in pheromone traps. Dispensers installed at 125 or 50 per acre, however, did not significantly reduce trap counts. Based on those results, a second set of trials was conducted in a 56-acre vine- yard east of Denair, Calif., to evaluate David Langone, S. Kaan Kurtural, California State University, Fresno, and Kent M. Daane, University of California Cooperative Extension, Parlier, Calif. BY Mating disruption of vine mealybug Phot0 by rebeccAh WAterWorth This project involved collaborators across California conducting a variety of field trials. Two alternate pheromone dispensers were investigated: aerosol spray cans or "puffers" (Puffer, Suterra LLC) and experimental Check- Mate membrane dispensers of different loads of pheromone. Evaluation of their efficacy was based both on the extent of VMB damage (the practical outcome) and how pheromones were distributed in the vineyard (theoretical explana- tion for our visible results). In Lodi, the efficacy of puffers was evaluated. In Fresno, the VMB response to pheromone release was evaluated to better understand VMB flight patterns. Figure 1. The puffer can be deployed in the vineyard (left), and with the lid open exposing the canis- ter of pheromone and electronic controls (right). Top: Female long-tailed mealybug on the orna- mental plant Ruscus (magnification 64x).