Spring Warm Up Brings Increased Threats to Vineyard Profits

May 20, 2019

Limit mealybug damage and leafroll virus with a mix of cultural and chemical controls

ST. LOUIS, May 21, 2019 /PRNewswire/ -- As temperatures warm up, so do mealybug populations and the potential for the devastating leafroll virus. Growers can preserve the health of their vines with a good understanding of how mealybug contributes to leafroll virus and how to protect their vines through an effective multi-layered solution.

"The biggest problem we've encountered with not controlling mealybug is the spread of leafroll virus. If you're not on an aggressive program for mealybug, it can cause significant damage to your vineyard in a short amount of time," said Gonzales, CA Pest Control Advisor (PCA) Shane Calabro.

Leafroll virus causes delayed fruit maturity, reduced quality and according to University of California, Davis, can reduce yield by 30 to 40 percent.

Mealybugs overwinter in the lower vine sections during the dormant period. In the spring, mealybug eggs begin to hatch under the bark and are often not seen by vineyard managers until the populations increase and move up the trunk. Infestations can result in reduced vine growth, defoliation, and disease.

"There is no cure for leafroll virus, so it's important to stay vigilant with a thorough program for mealybugs," said Paso Robles, CA PCA Matt Helm. Control of this pest requires a variety of approaches, including chemical control, cultural control, field crew education and pheromone traps.

Chemical Control
Grape growers can preserve the health and longevity of vineyards and prevent the spread of mealybugs with a Movento® insecticide application program applied around early bloom and again post harvest. The two-way systemic movement of Movento allows it to go through the xylem and phloem for complete plant protection, including the underside of leaves. According to trials conducted by Kent Daane with University of California, Movento provides the best protection for mealybug against industry standards. In trials conducted in California, treatment with Movento resulted in less than two percent fruit damage, while two competing products resulted in 20 to 30 percent fruit damage.

"I think Movento should be the foundation, the backbone of any program. If you're doing one thing for mealybug that season, it better be Movento," continued Calabro.

Cultural Controls
Cultural control and maintenance are critical to prevent the spread of mealybugs. Female mealybugs are unable to fly so their movement occurs through humans, equipment or natural dispersion, including by birds and wind. Growers are encouraged to use equipment in non-infested areas whenever possible or clean parts from all equipment when moving from an infested area of a vineyard to an unaffected one.

Field Crew Education
It's important to train field crews to identify the signs of mealybug in the vineyard. Field crews can monitor during pruning, leaf removal and harvest stages to help identify and mark infested areas.

Pheromone Traps
Understanding populations is essential for control. Pheromone traps can be used to monitor populations. This is most effective when mealybug populations aren't present. Researchers at the University of California recommend placing two pheromone traps for every 20 to 40 planted acres in late spring and checking them every two weeks through November.

Using a variety of mealybug monitoring and control efforts can lead to a clean field, healthy crop and increased yield year-after-year. For additional information on controlling mealybugs in grapes, talk to your Bayer representative or visit MealybugIPM.com.

Hear California PCAs talk about the challenges they face with mealybug control.

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