Winter Chores Necessary for Upcoming Almond Season

Entomologist Walt Bentley offers winter tips for almonds.

 Editor’s note: We welcome long-time entomologist and retired University of California Statewide Integrated Pest Management advisor Walt Bentley as our guest blogger this week.

Almond growers are in the middle of their winter chores as they start preparing for the upcoming season. Here are some tips and a wintertime to-do list:

Orchard sanitation remains important to control navel orangeworm and defend against aflatoxin contamination. Head into the orchard and check for mummy nut loads, where NOW can get their foothold. Remove and destroy those mummy nuts.

 Trees should be cleaned to less than two mummies per tree by this Friday in the Sacramento Valley, and fewer in the San Joaquin Valley where winter storms or bird and squirrel activity are not adequate for natural removal of the mummies. Blow or sweep fallen mummy nuts to the row center and destroy them by discing or flail mowing by March 15 where ground cover is not present. Moist orchard floor conditions provided by winter-resident vegetation and rain will enhance mortality of navel orangeworms in mummy nuts that have fallen from trees, according to the UC IPM website.

Here is an example of a colony of San Jose scale.
                                                                            - UC IPM photo

Check for San Jose scale, especially if you have been off a dormant oil program. While fewer orchards from Fresno north have been experiencing this problem, scale will surface from time to time. The UC IPM website, local extension farm advisor or your pest control advisor can help you examine for San Jose scale. Growers who participate in the San Joaquin Sustainable Farming Project receive helpful information about dealing with scale as well.

 Look for wintering leaffooted plant bugs. Walk through the orchard and look for that pest, which can be up to an inch long with spiked leaf-like protrusions on their hind legs. The bugs will aggregate under sheltered areas and large trees and they don’t move around during the winter. If you find an aggregation, follow them throughout the winter to estimate the mortality and spring population density, according the UC almond experts. Around mid-March when the pests start looking for food, growers need to start monitoring for dropped nutlets. UC IPM points out that there are no treatment thresholds for this pest in almonds.

Look for signs of leaffooted bugs.
                                  - UC IPM photo

“If bugs and their damage are evident, consider a treatment. Chemical control generally targets the overwintering adults that have migrated into the orchard with April or May applications.”

Remember, the winter rains will cause muddy conditions in the orchards. To avoid soil compaction, let the orchard dry out a couple days before driving through with a tractor.