Survey sites were established and monitored for mealybug, ant, and beneficial species. Obscure and long-tailed mealybugs were identified at all survey locations. No positive identification of grape mealybug has been made from any affected vineyards, although its presence is suspected due to recovery of parasite species known to parasitize grape mealybug. There does not seem to be a pattern of conditions that preselect the predominance of mealybug or ant species at any of the survey sites. Although predation was found at all sites it was not important as a control factor. Parasitism was found at three of the five sites, in very low levels. Determination of the seasonal development of each species under coastal conditions was not achieved during the 1995 growing season for three reasons. It was not considered prudent to release these species until positive identification of each was made. Obscure and long-tailed have been positively identified. In addition, pure colonies of the mealybug species were not available for release. Wet, cold weather conditions during the spring and early summer in the Edna Valley were also not conducive to a successful release. Due to the inability to complete objective 2 in 1995 the trial was amended to look at the efficacy of delayed dormant applications and inseason applications of short and long residual insecticides as well as a newly registered material reported to be effective in controlling mealybugs (Table 1). Timing of insecticide applications may be more critical than type of insecticide used when working with multiple species having different developmental cycles during the season. Dormant applications of chlorpyrifos have been successful in controlling grape mealybug populations in the San Joaquin Valley because it overwinters either as eggs or as newly hatched crawlers (Walt Bentley personal communication May 1996). In severely infested vineyards some in-season applications are also necessary. The most successful in-season treatments have been timed to a predominance of the early crawler stage of grape mealybug. In this trial monitoring of sticky tapes on canes indicated an early peak of crawler emergence in the first week of July. Treatments were applied the last week of June. Pre and post counts of leaves indicated significant reductions in mealybug numbers immediately after treatment with dimethoate and methomyl. Only dimethoate was consistent in being significantly different from the control in the number of crawlers captured on sticky tapes during the remainder of the season, and in significantly reducing the infestation of mealybugs in the clusters at harvest as compared to the unsprayed control.
/wp-content/uploads/2017/09/AFV-Header-Logo.png 0 0 AVF /wp-content/uploads/2017/09/AFV-Header-Logo.png AVF1995-11-16 13:42:462017-11-16 13:43:54Seasonal Development and Control of Mealybug Species in Central Coast Vineyards