What is in this article?:
- Vine mealybug infestations continue to increase in northern San Joaquin Valley vineyards, and their presence has led to greater reliance on insecticides and disruption of successful IPM programs.
- Although more vineyards are becoming infested, populations within infested areas are declining because the judicious use of insecticides has successfully lowered mealybug populations in areas that are infested.
Movento (spirotetramat) is a lipid biosynthesis inhibitor that has been shown to be highly effective when applied in spring or postharvest, and it is safe to beneficials. Nearly a dozen trials in Kern County have shown that Movento can be effective any time from April through June. In the same five trials previously referenced for Lorsban, applications of Movento in April, May, and June led to reductions in the percentage of clusters with mealybugs by 89.6, 74.2 and 80.1 percent, respectively, in July. Key factors related to Movento are that it must be used with a surfactant, coverage must be sufficient to cover the leaves but not allow runoff, and the product must be used with a period of at least eight weeks between the application and harvest to give it time to work. After application, Movento moves systemically in both the phloem and xylem and must be ingested by a mealybug, which then dies within a few days (crawlers) to several weeks (adult females) due the inability to generate new energy reserves. Postharvest Movento applications have been used very effectively in table grapes, and to some extent in wine grapes. The key to postharvest applications of Movento is that the leaf must be of sufficient quality to absorb the active ingredient. However, in wine grapes this is often not a possibility due to damage to the leaves during mechanical harvest or because harvest is conducted very late in the year.
Applaud (buprofezin) is an insect growth regulator that is most effective against the crawler stage, so it is best used twice in the spring — once when crawlers begin to move and two to three weeks later to control later emerging crawlers; optimal application dates for Applaud vary from year to year due to weather patterns such that monitoring is critical. It has a short pre-harvest interval (seven days) and is harmless to beneficials. In the five Kern County studies previously mentioned two applications of Applaud in April and May resulted in a 61.6 percent reduction in the percentage of clusters with mealybugs at harvest.