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April 14, 2021

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

In my last message to you, I shared a bit about the importance of early scouting. I’m sharing again because when it comes to scouting, you can never hear enough about the importance of taking a good look at your trees and at your orchards. This is especially true now, as the season is getting into high gear. 

It is critical that you are consistently evaluating what you see in your orchards. Diligence is key to an effective scouting program. 

A few tips that I always share about scouting with Certis Biologicals customers and PCA’s are:

  • Don’t leave it entirely to the experts – Even if you have a PCA, there is no substitute for personally taking note of what is happening in your orchards.
  • Come prepared – As you scout, make sure you have the tools you’ll need to keep effective notes, including a clipboard, scouting chart and your camera or smart phone. Documenting damage, evidence of pests, location in your orchard and areas impacted can help you compare over time.
  • Leave no stone unturned – When scouting, be sure to look everywhere. Don’t ignore your orchard floor, tree trunks, cartons/wraps and anywhere else where pests, disease and weeds may live. Close examination of these critical areas combined with early detection can benefit you in controlling an outbreak.
  • Know what is out there – Follow pest alerts, work closely with your PCA and local extension officials, talk to your nearby grower neighbors…do whatever you can to get an idea of what pests and disease are looming in your area.
  • Use what is available – IPM software and apps exist to help make tracking and managing your overall program more convenient.

When you are scouting, what should you be looking for right now? Here are some pests and diseases that I’d recommend you have on your radar:

  • Peach Twig Borer (PTB) – For PTB, I’d recommend starting by calculating your degree day using the UC-IPM’s calculator. PTB overwinters as 1st or 2nd instar larvae in the limb crotches of young branches. As weather warms, the larvae begin feeding in the hibernacula and create chimneys of frass. As the PTB growth stage progresses, the larvae emerge and start feeding on flower buds and new foliage. They then mine into tips of new shoots and create dead shoot tips, referred to as flagging. In April and May, the moths that develop from this overwintering generation emerge. Remember, if you see evidence of PTB in your trees, Deliver® Bt Biological Insecticide is an effective tool for control that does not negatively impact bees and/or other beneficial insect species.

  • Earwigs – All of the young tree plantings that we see around the Valley right now are susceptible to earwig populations increasing in their trunk protectors and wraps. Left unchecked, earwigs can severely damage young trees by attacking the trunk and feeding on young shoots and new growth. Look in your orchards for leaf damage, either skeletonizing or signs of external feeding on new shoots and young leaves.  These pests feed at night, so leaf damage is the best way to know they are there unless you see them by the base of your trunks or in the cracks of the soil. Timing is everything when it comes to effective pest control so be sure to take corrective action when earwigs are first identified in your orchard. A single application of Seduce® Insect Bait can control earwigs for 30 to 60 days.

  • Mites – UC-IPM recommends that you monitor for mites at least once every two weeks from March to early May. You can see mite pressure through feeding on leaves on the lower interior of trees. Using a hand lens to examine leaves will help you see mite eggs that may be present as well. If mites are a problem, I’d take them out with PFR-97 20% WDG. 

  • Leaffooted Plant Bugs and Hoppers – When mites are present, you can bet that leaf-footed plant bugs and grasshoppers cannot be far behind. If you see either of those pests hanging around or see evidence of their eggs or damage, BoteGHA® is a great rotational product to add to your IPM plan to help maximize control.

  • Alternaria – Large brown spots on your exposed leaves could indicate an issue with Alternaria, especially if you have trees planted in an east-west direction and have susceptible varieties including Carmel, Sonora, Monterey, Winters and Butte. Don’t let either Alternaria and/or leaf blight in your orchards cause damage to your trees that significantly impacts your bottom line. Catching either of these diseases early is key to effective control, deploy the plant activator technology of LifeGard® to arm your trees for successful control. In addition, Cueva® is a long-standing proven and reliable control product for these two diseases.

The most important thing to remember about scouting is that there are no shortcuts to effective disease and pest management. A program based on early detection will pay dividends in the future for your orchards and farms.

If you need help scouting, knowing what you are seeing, or the control we recommend for it, please reach out to me and the Certis California team at

We are always here for you.

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

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