There are currently five neonicotinoid active ingredients registered for use in grapes in California. This includes imidacloprid (foliar Provado, soil-applied Admire, plus generic products), clothianidin (Clutch), acetamiprid (Assail), and thiamethoxam (foliar Actara, soil-applied Platinum). In general, foliar neonicotinoids are effective against leafhoppers and in most cases grape mealybug; however, they are not very effective against vine mealybug. The primary exceptions are Clutch and to some extent Assail that have recently taken on more importance as late-season knockdown products due to the removal of grapes from the labels for Lannate and Dimethoate.

In most cases neonicotinoids for vine mealybug are most effective when applied through the drip system. In sandy soils Admire and Clutch (both with low water solubility) can be effective against vine mealybug when applied from April through June; Venom and Platinum (both with high water solubility) have not been effective in trials in sandy soil, but they have been somewhat effective in northern San Joaquin Valley vineyards with sandy loam and heavier. Research in a North Coast vineyard with heavy clay soil showed that drip-injected Venom and Platinum were somewhat effective late in the season but Admire and Clutch were not effective. Movento and Applaud were most effective in the trial.

Other Considerations in Insecticide Use. Within any management plan it is important to implement good resistance management programs. For example, if Lorsban and Movento are used during a particular year to control vine mealybug, the grower in the following year should consider using management programs based on Applaud and soil applications of Admire, Clutch, or Platinum. Because of its efficacy, some growers are using Movento annually – this strategy is a recipe for the development of insecticide resistance.

To get newly found populations under control, a good strategy is to use a combination of two insecticides, such as Lorsban plus neonicotinoids, neonicotinoids plus Movento, Movento plus Lorsban, or neonicotinoids plus Applaud.

It is important to note that the costs of using insecticides for vine mealybug control can be offset by the control of other pests. For example, the soil-applied neonicotinoids virtually remove grape leafhopper as an economic pest, and control or suppression of leafhoppers has been seen for up to two to three years after a single application. The cost of Movento and soil-applied neonicotinoids can be offset by nematode suppression and control of leafhoppers and thrips. Also, Applaud is effective on soft scales and Lorsban is effective on ants.

References

Daane, K. M., G. Y. Yokota, M. P. Pryor, W. J. Bentley, J. M. Hashim-Buckey, D. R. Haviland, S. Rill, M. Cooper and J. G. Millar. Selecting the needed mealybug control in table grapes. Proceedings of the San Joaquin Valley Table Grape Symposium, Visalia, CA Feb. 2, 2011.

Haviland, D. 2009. Maximizing vine mealybug control. Western Farm Press, June 15, 2009.

Smith, R. and L. Varela. 2009. Vine mealybug control trial 2009. Web site: http://cesonoma.ucdavis.edu/files/27847.pdf.

(David Haviland, Entomology and Pest Management Farm Advisor, UCCE Kern County, Steve Quashnick, Viticultural Services Manager, Wilbur Ellis Company)