Good afternoon Patty,

My name is Logan Bennett, I am the Small Farms Program Coordinator for Oregon State University in Douglas County.

Dealing with pests on multiple crops can be tricky. Since there are cherries, plums and apples, you are looking at several pests that could get into your fruit trees. Due to the proximity of the trees to the pond, I would encourage you to use cultural control methods if possible. I will discuss each applicable cultural treatment below per pest, and then I will talk about chemical options at the end.

Apple Maggot and Codling Moth: 

 Codling moth and Apple Maggot are pests you are likely to encounter.

Sanitation of the orchard is key in the management of both Codling Moth and of Apple Maggot. Make sure to remove and destroy any affected fruit from the Orchard. This reduces the ability of both pests to repopulate, and specifically does not allow apple maggot to enter the soil and pupate. Pick up and destroy any fallen fruit starting in August and continue through harvest.

Using traps can be an effective way to manage low populations of Apple maggot as well. Traps are typically made with an adhesive and a scent lure, which draws the flight stage of the maggot in. traps can be used to manage low density fly populations by trapping adults before they lay eggs in the fruit. Place 1 apple maggot trap per apple tree that is less than 8 feet tall. In mediums sized trees, use 2-4 traps, and in large trees (20 + feet), use 6-8 traps. Clean traps every week, and replace adhesive every 3 weeks. This is an effective method for low populations of Apple Maggot. There are also pheromone traps available for Codling Moth.

Thinning the clusters of apples can also help reduce codling moth populations. Reducing the points of contact in each bunch helps stop the larvae from moving fruit-to-fruit and lowers pupation success. Once again, make sure to be looking for any damaged fruit, especially with frass-filled holes and removing them when found. Destroy any damaged fruit found. You can also put bands of corrugated cardboard on the bottom of the trunk of each tree, which attracts larvae looking for a place to pupate. Bands should be attached to the trunk in May, and you should remove them before the adults emerge in mid-June. You can reapply bands later in the summer for the subsequent generations.

Western Cherry Fruit Fly:

Monitoring for Western Cherry Fruit flies using pheromone traps can be effective as a management method if you are growing early season cherries. Once a fly is observed, cherries should be harvested within 8-9 days.

Spotted Wing Drosophila (SWD), Cherries & Plums:

SWD has become a serious pest in Oregon in the last decade. Since their discovery here, there has been a massive movement to research treatments for this pest. Unfortunately, they will infest both the cherries and plums in your orchard. SWD use surrounding vegetation as habitat, and late emerging flies can use it to overwinter into next season. Managing surrounding areas to reduce humidity and low-heat spots for flies to escape to can reduce the population of flies. Thinning the canopy of the trees can also have a similar effect. Using tools like weed mat can help mitigate pupae from burring into the soil underneath, and using irrigation strategies like drip can help reduce populations. With SWD, it is important to mitigate microclimates within your orchard that promote humidity, and thus habitat, of the flies. SWD traps are available, which are similar to a jar with holes drilled into the top and upper portion of the sides. The traps use a pheromone bait and a liquid (like apple cider vinegar) to lure in flies and then trap them in the liquid. You can then count the flies and determine population.

Chemical Methods:

If choosing to use chemical formulations, make sure to read the label of each pesticide, and confirm that you can use it in your orchard, and make sure that the chemical is labeled to use relative to the distance between the trees and pond. If using a chemical option, I highly encourage you to use traps in conjunction with the pesticides, and only spray when you have reached the economic threshold of each pest. I have attached our PNW Handbook Guides below with descriptions of each pest, their lifecycles, economic thresholds, and spray timing.

Chemicals:

Kaolin Clay: Kaolin based products have been shown to be effective on several insects, and some formulations are organically labelled. Some formulations are labelled on plums, apples, and cherries. Make sure to check the label for treated pests, crops, and environmental hazards.

Spinosad: Spinosad products have been shown to have a high level of control on SWD and Western Cherry Fruit Fly. However, this chemical formulation is toxic to bees. Consult specific formulation label for timings of applications, treated pests, crops, and environmental hazards.

PNW Handbooks:

PNW Handbook, Apple Maggot: https://pnwhandbooks.org/insect/tree-fruit/apple/apple-apple-maggot

PNW Handbook, Codling Moth: https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth

PNW Handbook, Western Cherry Fruit Fly: https://pnwhandbooks.org/insect/tree-fruit/cherry/cherry-western-cherry-fruit-fly

PNW Handbook, Spotted Wing Drosophila (Cherry): https://pnwhandbooks.org/insect/tree-fruit/cherry/cherry-spotted-wing-drosophila

PNW Handbook, Spotted Wing Drosophila (Plum): https://pnwhandbooks.org/insect/tree-fruit/plum-prune/plum-prune-spotted-wing-drosophila

If you have more questions, or would like to talk in detail about any of the aforementioned material, please don’t hesitate to reach out to me.

Thanks,

Logan

Please visit our website for contact information, hours, resources, and educational workshops.

Logan Bennett

Small Farms Program Outreach Coordinator

Oregon State University | Douglas County Extension

1134 SE Douglas Ave, Roseburg, OR 97470

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