With the summer growing season hitting its stride, so too are the pests that live off the fruits of your labor.
The various species of mealybugs are one of those pests that require attention. In general, three species impact grape growers, depending on your location and variety grown:
• Grape mealybug: Pseudococcus maritimus
• Obscure mealybug: Pseudococcus viburni
• Long-tailed mealybug: Pseudococcus longispinus
Grape and obscure mealybugs lay yellow to orange eggs within an egg sac; long-tailed mealybugs give birth to live crawlers. Crawlers of all three species are yellow to orange-brown in color, explain Integrated Pest Management experts with the University of California.
The species also infiltrate vineyards a little differently. For instance, the grape mealybug has two generations each year and overwinters as an egg or crawler in or near a white, cottony egg sac under loose bark and in the cordons or upper portions of the trunk. In spring most grape mealybug crawlers move toward the base of spurs and then onto expanding green shoots, reaching maturity in mid-May to early June.
Most females return to old wood to lay eggs that hatch from mid-June to July. First generation crawlers then move out to the green portions of the vine to feed on fruit and foliage in late June or early July; mostly immatures are seen through July, so be sure to be on the lookout now for grape mealybugs.
Adult females will appear in late summer and early fall. Some females will oviposit in the fruit clusters, but the majority of the females return to the old wood to lay the overwintering eggs.
Keep in mind susceptibility to mealybug damage varies by variety. It is worse on varieties that produce clusters close to the base of the shoot because the fruit often touches old wood. Mealybugs damage grapes by contaminating clusters with cottony egg sacs, larvae, adults and honeydew. Often the honeydew is covered with a black sooty mold. All three species can transmit grape viruses, so not only do they have an immediate impact on the crop, they have multiple impacts on your profits.
Click here for monitoring tips and more information on mealybugs.
Also continue to monitor vineyards for spider mites, since populations of this pest can quickly explode when conditions are right. Make sure Acramite® 50WS miticide, which delivers good knockdown mite control without affecting beneficials, is part of your arsenal. Acramite eliminates the majority of undesirable mites, giving beneficial insects a head start in keeping mite populations in check. Plus, its unique carbazate chemistry also makes Acramite an excellent rotational miticide for resistance management.
Always read and follow label directions.
Also visit with your PCA or Chemtura AgroSolutions™ representative for additional ways to enhance your control program and ensure a successful season:
• Mike Ansolabehere, Southern San Joaquin Valley: (661) 304-3023; email Mike.Ansolabehere@Chemtura.com
• Matt Loftus, Central San Joaquin Valley: (559) 960-1112; email Matthew.Loftus@Chemtura.com
• Eric Leer, North Central California: (209) 531-6478; email