Monday, August 29, 2011

Ant Damage Risk Rises Longer Almonds Are Left on Ground

Editor’s note: We welcome again our guest blogger UC IPM entomologist Walt Bentley, whose specialty includes managing pests in almonds.

Nonpareil almonds are now being removed from trees in Fresno and Madera counties. Many of these orchards are beginning to windrow the nuts and will be delivering the first loads to the huller within a day or two. 

This is good news in terms of Navel orangeworm and peach twig borer infestation.  It is also good news in terms of ant damage. For Nonpareils and other soft shell varieties, the shorter time the nuts are on the ground, the less ant damage.

Remove almonds from the orchard floor once they are sufficiently dried.
However, ants can still be a problem if nuts are left on the orchard floor for too long.  Past research has shown that, depending on ant density, damage can increase by 0.5 percent per day as nuts remain on the ground. Don’t delay in removing nuts from the orchard floor once they are sufficiently dried.

UC IPM photo by Jack Kelly Clark
The high temperatures have aided us in drying the nuts quickly. Such temperatures also reduce the foraging time for ants. Both California fire ants and pavement ants do not forage on nuts when the ground temperature is above 95 degrees. Neither of these species is a problem on hard shell varieties.

We have also seen mites developing in some of the orchards. At this time of year, web spinning mites are not a serious issue. Many farmers and pest control advisors will worry if they are seeing webbing but the crop has developed and the impact of leaf feeding is very minor.

Many believe early defoliation will impact next year’s nut set. This impact has been tested and shown to be untrue.  So, be patient and don’t worry about the spider mites now. We are close to the final leg of the race and we are in a good position for a clean harvest. 
Walt Bentley is a long-time entomologist with the University of California Statewide Integrated Pest Management program at the Kearney Ag Center in Parlier.

Cotton Field Day Reminder: Don’t forget to remind your colleagues in the cotton business about our upcoming Cotton Production and Pest Management Field Day. It will be Sept. 7 from 10 to 11:30 a.m. at the McCurdy Farm, south of Firebaugh. UC Cooperative Extension cotton specialist Dan Munk will give important tips about timely cotton termination and pest management practices to avoid sticky cotton. I will give a field scouting update. Check our Sustainable Cotton Project website for directions.  The event offers 1.5 hours of continuing education credits. It’s a perfect opportunity to have your questions answered.

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