There are many factors that go into a bottle of wine that often are taken for granted.
For instance, when a cork is popped, how much thought is devoted to the winegrowers?
Without them, there wouldn’t be healthy grapes to make the wines we enjoy.
Grape vines, being natural and alive, are subject to a host of threats, such as powdery mildew, invasive weeds, insects and other pests. For the wine grape farmer, managing these threats is critical to the vineyard’s near- and long-term viability.
Lodi winegrowers consistently search for new and effective methods to deal with issues in the vineyards. Most growers would agree that when it comes to dealing with threats, natural practices are almost always preferred.
Last Friday evening, Michael Klouda, viticulturist with Michael David Winery and owner/winemaker of Michael Klouda Wines, and Jim Grady, vineyard manager for Grady Family Vineyards, engaged in an experiment they hope will help provide a natural deterrent to the pesky mealybug.
Klouda and Grady distributed Mealybug Destroyer Beetles (Cryptolaemus montrouzieri) through parts of their vineyards. The beetles were provided by Associates Insectary, a grower-funded entity and America’s oldest commercial insectary.
Klouda spread the contents of a dozen large vials, each containing 500 or more of the tiny beetles, through a vineyard of head-pruned Zinfandel at Bare Ranch in Lodi, while Grady took the other eight vials and spread their contents on his Petite Sirah vineyard.
Conventional products to control mealybugs and other pests have been employed for decades and are presently being used, but if there is a natural alternative, why not try it?
Klouda tapped the beetles from each vial onto random vines every third row. The beetles have about a 30-day lifespan. If enough survive the initial deployment and lay eggs, up to 400 per female, perhaps their population will help control the mealybugs. According to plant pathologist Dr. Stephanie Bolton, natural predators such as the beetles play an important role in lowering overall pesticide risk across a farming region: they consume insects that may be building resistance to pesticides.
Mealybugs occur in all parts of the world and especially thrive in moist, warm areas. Though they don’t cause significant damage by feeding on the vines, their sugary excrement promotes mold formation on grape clusters, and they also transmit leafroll viruses. Leafroll virus has the potential to decrease yield and quality of grapes, lower sugars in the berries, and reduce the lifespan of a vineyard. Male mealybugs can fly, so a male mealybug carrying the leafroll virus quickly can damage a vineyard, sometimes irreparably.
Mealybugs have an ally: Ants eat the mealybugs’ excrement, so they protect the mealybugs by attacking the beetles. There’s a lot going on in the vineyard that most can’t see.
Lodi winegrowers also are using pheromone disruption as another natural deterrent. This year, Klouda said female mealybug pheromones were sprayed in some of the vineyards he manages.
“It confuses the male, such that the males can’t find where the females are, so they can’t mate,” he said. “It doesn’t work, though, if you have high populations of mealybugs under the bark because they bump into each other and make babies.”
Bolton and the Lodi Mealybug Biocontrol Research Focus Group distributed mealybug traps for growers to hang in their vineyards as a tool to decide on whether to employ a pheromone mating disruption program or other treatment, and to see if there are new areas invaded by mealybugs
“It’s a statewide thing; you can’t say it’s just Lodi,” Grady said. “It’s just something we’ve had to learn how to deal with, and we’re learning new stuff all the time.”
Contact Bob Highfill, marketing and communications manager with the Lodi Winegrape Commission at email@example.com. Follow him on Twitter @bobhighfill and @lodi_wine.