Monday, April 16, 2018

Something is Already Starting to Bug Almonds This Season

Things are getting a little buggy for almond growers.

That’s not good news, especially this early in the season, reports almond field scout Jenna Mayfield. This concern compounds the trouble already experienced by growers because of the February freeze and March and April rains. Oh yes, we forget to mention the dry December and January weather.

The sun made an appearance in the Valley last week.
“It has been weird. There will be all kinds of crop losses,” Jenna says. But that won’t be known until harvest time.

After a number of growers wrapped up another application of fungicides a week ago Sunday, Jenna had time later in the week to venture into the orchards to inspect the progress of almonds. The nuts are a good size, she says. 

Young almonds are growing nicely.
But she adds:  “Leaffooted plant bugs are out there. Everyone is worried about that.” Jenna says growers are staying vigilant and keeping a close eye for signs of pest damage.

The leaffooted plant bug (LFPB) gets its name because of the leaf-like enlargements found on the hind legs. Adults are about an inch long with a yellow or white zigzag line across its flat back. UC Integrated Pest Management called LFPB a sporadic pest for almonds.

Damage can be significant when weather conditions are right. Here’s what UC IPM says: “Feeding by adult leaffooted bugs on young nuts before the shell hardens causes the embryo to wither or abort or may cause the nut to gum internally, resulting in a bump or gumming on the shell. It can also cause nut drop. After the shell hardens, adult leaffooted bug feeding can still cause black spots on the kernel or wrinkled, misshapen nutmeats.”

Experts say the bugs often show up in April in search of food after overwintering in nearby fields. Jenna noted she usually spots the pest in May. “They seem to be a little early this year.”

Here's a leaffooted plant bug.
Two indicators of LFPB problems are gumming found on the outside of the nut or aborted nuts on the ground. However, there is a seven- to 10- day lag between feeding and when the gumming and nut drop take place. By the time these signs are evident, the pest may have already moved on.

“Treatment thresholds have not been developed for this pest in almonds, but low numbers of bugs can cause substantial damage. If bugs and their damage are evident, consider an insecticide application; apply insecticides through May to target the overwintering adults that have migrated into the orchard," UC IPM says.

You can see the LFPB damage to the almond kernel.
“Unfortunately, the broad-spectrum products that are most effective against leaffooted bugs are also very disruptive to biological control agents of spider mites and other almond pests. Later applications are not needed when numbers of overwintering adults have declined or nymphs are the only life stage present, as their mouthparts are too small to feed on the kernel.”  It’s important for growers to weigh the consequences when they are making an insecticide choice to avoid secondary problems that can flare up after use of broad spectrum materials.

Given the all the weather issues and early pest concerns, growers are pressing on and “hoping for the best,” Jenna says.

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