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WSU Decision Aid System Update August 2023

Written by Liesl Oeller, Washington State University, July 26, 2023

Impact of Bin Piles on Codling Moth (CM) Populations

Bins that are brought into the orchard mid-season can harbor overwintering CM larvae from the previous year. Because these CM are transported from outside the orchard, their phenology will not be in sync with the internal orchard population. Therefore, CM adults emerge from bins at different times than predicted by the model.

When do CM colonize bins?

The majority of CM enter the bins when the bins are in the orchard before harvest. CM prefer wood bins to plastic, as there are more crevices to hide in and build hibernacula. These sites can provide overwintering substrates for CM entering diapause as early as June or July.


Extra pheromone-baited traps should be placed around bin piles to monitor moth emergence. Border sprays of 4-5 rows around external sources or bin piles may be necessary if these areas are identified as problems. A good monitoring program can help pinpoint these problem areas so that controls to protect fruit can be applied when necessary.


First, using plastic bins for harvest will greatly mitigate bin infestation by codling moths. Second, sterilize bins before they go back out to orchards. While there are no materials registered for spraying bins, bins can be run through a “bin cooker” to sterilize them at the warehouse, before returning to the field. Third, minimize the amount of time bins are in the orchard; do not bring them into the orchard until right before harvest.

Apple Sunburn Model

As apples continue to develop and the summer heat progresses, the DAS apple sunburn model becomes important to check. This model allows you to enter your apple cultivar, fruit diameter, and canopy density. It then uses temperature, cloud cover, humidity, and wind speed data to predict apple sunburn risk.

screenshots of conditions and data table

Fruit Growth Model

The DAS fruit growth model is also relevant at this point. This model shows the current percent of max fruit size and projected full size of common apple cultivars like Cosmic Crisp, Gala, and Honeycrisp. There is also a size calculator where growers can enter their fruit sizes and get the projected full size and box size.

screen shots of the size table and the size calculator

Spray Selection Tool

We are excited to introduce a new feature to DAS- the spray selection tool. The Washington State University tree fruit crop protection guide written by the WSU Tree Fruit Extension Team has always been available online, and now this tool is integrated into the DAS platform. The spray selection tool allows users to select their crop, growth stage, and target pest or pathogen. The guide then shows a list of possible materials to apply, and their efficacy on your target and other important pests.

When you select the material you want to spray, you are given more information on the efficacy, type of chemical, rate per acre, REI, and more. This tool will be available in the coming weeks, so keep an eye out on DAS and coming updates!

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Liesl Oeller

Liesl Oeller
Washington State University
(509) 335-5815



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