By mid-May, much of the state’s vines were at least a few days ahead of schedule and in some areas such as the northern San Joaquin Valley, PCAs are reporting the crop is about a week to 10 days earlier than usual. While not too much vine mealybug activity has been seen, as of yet, some have begun recommending sprays.
“Vine mealybug continues to spread to new vineyards in all of the infested regions,” says Kent Daane, Biocontrol Specialist, UC Berkeley/Kearney Ag Center. “However, the control tools, including insecticides and monitoring, have improved so that fewer growers are getting damaged - although control costs are still high.”
The cold snaps throughout the winter and early spring haven’t reportedly impacted the pest very much. “The mealybug appears to be quite hardy,” Daane says. “We just saw a very large population at a Fresno site, and there the January temperatures were quite low.”
Standard control measures are still the first line of defense for most growers, according to Daane “The products of choice are: delayed dormant Lorsban (chlorpyrifos), in-season (May-June) application of Applaud (IGR-buprofezin) or Admire or Venom (both types of neonicotenoids) through a drip system. Other materials provide some knock down, but are not typically as complete.”
In the meantime, the university continues to work on alternative methods of suppressing the pest. “We are working on biological controls, mating disruption and ant controls,” Daane says. “A number of insecticide companies have some new products for registration in 2008, and these look very promising.”
In other areas where the pest has not yet become established, the diligence is no less intense. “I haven’t heard of any new infestations in this area,” says Lynn Wunderlich, UCCE Farm Advisor for El Dorado and Amador Counties. “However I think the vine mealybug is a continuing threat for foothill grape growers. We’re focusing on identification and preventing the spread. We now understand that mealybugs can be spread by wind, birds and people. So, especially for foothill farms in Amador where a lot of contract labor is used from the infested Lodi area, it’s important that growers ask workers come to their farms with clean clothing.”