University of California Cooperative Extension farm advisers have warned growers to be on the lookout for the leaffooted plant bug in the southern San Joaquin Valley.
The inch-long bug, which inserts its stylet through the hulls into developing pistachios and almonds to feed, is always found in scattered pockets in the valley, says David Haviland, a UC farm adviser in Kern County.
But some years, probably because of climatic conditions, the pest becomes a more widespread problem. 2006 was one of those years.
And it appears that 2011, with its quick warm-up, also may be one of those high leaffooted plant bug years, Haviland says.
Growers have begun spraying their orchards with insecticides to protect them from the often-elusive pest.
Some almond varieties appear more susceptible, with Fritz leading the list. Sonora and Butte also are more susceptible.
"They'll go after the more susceptible varieties," Haviland says. "But if you don't have highly susceptible varieties, it's not like they aren't going to feed."
Nuts damaged by leaffooted plant bug feeding shortly after bloom will blacken and drop.
If nuts are damaged during the period when they are enlarging, the damaged tissue turns black.
After shell hardening in June, the bugs may cause kernel necrosis, which isn't obvious from the exterior.
The nut meat is darkened and will be considered a defect during sorting.
For more information on the pest, inclluding treatment recommendations, visit UC IPM.