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Pests are eating your profits!

August 4, 2021

By Curt Nelson, Certis Biologicals Regional Manager, CA San Joaquin Valley

We are in the final stretch of the tree nut growing season here in California and the Certis team is busy helping growers like you finish strong and protect your trees, nuts and profits right to the very end. 

While your focus is on a safe and effective harvest, there are some pests out there that are focused on damage and destruction. Even as you are preparing for and beginning harvest, it’s crucial that you be on the lookout for codling moth, oriental fruit moth and navel orangeworm (NOW) so you can treat as necessary.

Calculate Degree Days

We looked to our friends at UC-IPM to help provide some assistance in calculating degree days, especially for codling moth and oriental fruit moth. If you’d like to hone your degree counting skills, they even have a nice degree days video that can help. Codling moth has two to four generations a year and UC-IPM recommends that you continue monitoring your traps and accumulating degree days until your crop is harvested or until numbers decline in late September. 

Your degree day calculations will help you determine if and when you need to treat for these pests.

Don’t Delay

It’s important, especially if you have issues with these pests, to harvest your nuts as soon as you can. UC-IPM recommends that you harvest when 100 percent of nuts are at hull split at the 6-8 foot level of your tree canopy. If you have an early-harvest variety such as Nonpareil, your risk of infestation by NOW is greatly reduced if you harvest before third-generation eggs are laid.

Let Biologicals Help

Remember, one of the key advantages to biologicals that can be a an important benefit during harvest is that many of our products have low REI’s and PHI’s so a treatment won’t delay your harvest schedule. Certis’ CYD-X® granulosis virus can be the key you need in a late treatment for codling moth in your walnut orchards. CYD-X can be used in either conventional or organic orchards and has a short 4-hour REI and a 0-day PHI. Madex HP®, also OMRI-Listed® and NOP-Approved for organic production, can be a powerful tool for control of oriental fruit moth.

For NOW populations, Deliver® Biological Insecticide has a higher concentration of the insecticidal Cry1Ac crytoxin than any other Bt product. It’s highly effective, flexible for use on conventional or organic orchards and has the 4-hour REI and 0-day PHI you need during harvest. 

Don’t Forget to Sample

We all know that harvest is stressful, but its important to remember to take samples during harvest so you can be better prepared for the next growing season. UC-IPM recommends that you collect and crack out 1,000 nuts during harvest so that you can identify pests present in your orchard and assess the damage they did. If you need help identifying pest damage, I rely upon UC-IPM’s handy guide. Use that guide to tell the difference between codling moth damage and NOW damage so you can plan your IPM accordingly next season. 

Remember, as you are harvesting, your best tools can be diligence and information. The Certis Biologicals California team is here to help you finish this season strong and protect your crops to the very end.

You can always reach out to us over email at

This series is part of a partnership with Tree Nut Farm Press. You can read the original here.

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