Preventing the Threat of Vine Mealybugs in Your Grapes

May 10, 2022

First discovered in 1994 in the Coachella Valley, vine mealybugs (VMBs) have been significant pests in the grape-growing regions of California. Over the years, these mealybugs have spread into all major production grape areas.1 As California makes up 98% of commercially grown grapes in the U.S.,2 the vast expansion of these pests into crucial grape-growing regions is alarming. Here are ways vine mealybugs can create serious challenges for a grower’s operation, as well as preventive measures to keep them at bay.

Mealybugs 101: What, Where and Why

Full-grown female VMBs are oval with flat, segmented bodies. Though difficult to spot, they are often seen covered in a waxy coating that forms spines.1 VMBs can be found on berries and leaves and thrive in vigorous vines with thick canopies. As they feed, they produce a sugary excretion, known as honeydew, that supports the growth of sooty mold. They also produce egg sacs and reproduce prolifically.

VMBs contaminate grape bunches which can impact yield potential, harvest and overall vine health. VMBs are also a vector of grapevine leafroll virus, which can not only reduce yield by up to 40 percent3, but also cause leaf discoloration, reduce fruit quality and impact production in future seasons.

When asked, Shane Calabro, certified pest control advisor, says, “the biggest problem we’ve encountered in not protecting for mealybugs is the spread of leafroll virus. If you’re not on an aggressive program for mealybugs, vine or grape mealybugs, the spread of leafroll in this area is really ramped up, and it can cause significant damage to your vineyards in a short amount of time.”

Best Management Practices

Addressing and preventing VMB infestations can be best managed through a variety of cultural and crop protection practices. Movement of equipment and people from vineyard to vineyard is a common means of introducing and spreading mealybugs. Practicing good sanitation when moving equipment or workers into a vineyard is recommended. Additionally, solutions within the Bayer grape pest control portfolio can help growers successfully manage these pests.

Bayer Grape Portfolio Solutions

Due to vine mealybug biology, reactive management programs are not as successful as proactive management programs.

Movento® insecticide from Bayer is a systemic insecticide that can move within the plant via both the phloem and xylem. This powerful, two-way movement provides broad spectrum protection to the plants, including those in dense crop canopies, new shoots and root systems. Movento applications are best tankmixed with a spray adjuvant/additive with spreading and penetrating properties to help maximize leaf uptake and two-way movement.

Using Movento as part of a proactive mealybug management system for early-season (light population density) and mid-to-late-season (moderately high) applications can provide effective control of these insects. Trials conducted by the University of California Cooperative Extension, Kern County, indicated that an early-May application of Movento led to a significant decrease in the number of VMBs found on grapevines.


Additional solutions in the Bayer grape portfolio include Admire® Pro and Sivanto® Prime insecticides. Admire Pro can deliver effective control of many sucking and chewing insects, like VMBs, while also helping stop the transmission of certain viral diseases. Growers will also find that Sivanto Prime precisely targets key damaging pests while helping safeguard beneficial insects.

Though small, vine mealybugs can cause major damage to vineyards by reducing vine health, yield and fruit quality which ultimately impacts growers’ profits. Growers who proactively manage this pest can rest a little easier.

ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Not all products are registered for use in all states and may be subject to use restrictions. The distribution, sale, or use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. Check with your local dealer or representative for the product registration status in your state. Admire®, Bayer, Bayer Cross, Movento,® and Sivanto® are registered trademarks of Bayer Group. All other trademarks are the property of their respective owners. For additional product information, call toll-free 1-866-99-BAYER (1-866-992-2937) or visit our website at Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. ©2022 Bayer Group. All rights reserved.

Work Cited

1 Varela, L. G., Haviland, D. R., Bentley, W. J., Zalom, F. G., Bettiga, L. J., Smith, R. J., Daane, K. M., Battany, M. C., Granett, J., Phillips, P. A. & Purcell, A. H. (2019, April). Agriculture: Grape Pest Management Guidelines Vine Mealybug. University of California Agriculture & Natural Resources. Retrieved February 2022, from

2 Davis, Geisseler, D., & Horwath, W. (2016, June). Grapevine Production in California. University of California.

3 Naidu, R., Rowhani, A., Fuchs, M., Golino, D., Martelli, G. (2014, September) Grapevine Leafroll: A Complex Viral Disease Affecting a High-Value Fruit Crop