Agriculture: Walnut Pest Management Guidelines


This year-round IPM program covers the major pests of walnut in California.

About Harvest

What should you be doing during this time?

Harvest nuts promptly to reduce potential for navel orangeworm damage and to preserve kernel quality.

Sample nuts at harvest to evaluate your pest management program.

  • Distinguish codling moth from navel orangeworm damage.
    • Navel orangeworm has brown, crescent-shaped marks behind the head, and leaves copious frass and webbing inside the shell.
    • Mushy black hulls with no kernel damage and black stained shells indicates walnut husk fly.
  • Black hulls with peduncle (stem) still attached may indicate Botryosphaeria infection.

Be aware that nuts with dried black hulls can also indicate a water management problem. Evaluate this season’s management program and plan for the next season’s management.

Text Updated: 07/17