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Natural, not harmful fruit tree pesticides #857819

Asked January 25, 2024, 2:16 PM EST

I have Apple and cherry trees on my property in Bend Oregon. Is there anyway to prevent the fruit maggots without applying harmful chemicals or killing beneficial insects? How do I keep my fruit organic and free of worms? I want to be very careful not to harm pollinators.

Deschutes County Oregon

Expert Response

Hi Kathryn,

Thank you for your question and your concern to protect pollinators and beneficial insects.

The worms in apple trees are most likely codling moth. The caterpillar of the codling moth is the common ‘worm’ in a wormy apple or pear. The codling moth rarely affects cherry and typically only occurs if there is heavy infestations of apple or pear nearby. It’s possible the cherries could have the maggot of the cherry western fruit fly so would need a photo or sample to know for certain. The fruit fly larva is about 8mm long while the codling moth larva full grown is 12-20mm long. Do you recall seeing a difference in size?

The OSU Extension Service has a program called Project Happy Apples to assist local residents with control of codling moth (including non-chemical management). You can view past newsletters and sign up for the newsletter here:

https://extension.oregonstate.edu/newsletter/project-happy-apples

Here is another link for more information and control tactics:

https://pubs.extension.wsu.edu/codling-moth-and-your-backyard-fruit-tree

Please feel free to contact me directly with any further questions!

Lisa

Lisa Cowan

Outreach Program Coordinator – Community Horticulture Program

Oregon State University

OSU Extension Service – Deschutes, Crook, Jefferson Counties

3800 SW Airport Way, Bldg #4

Redmond, OR 97756

Tel.:<personal data hidden> (direct line) I<personal data hidden> (x79590 - main line)

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An Ask Extension Expert Replied January 29, 2024, 4:49 PM EST

Hi Lisa,

Thanks for your reply. I think you are right, it is the western fruit fly in the cherries and the coding moth in the apples. I will look at your links below to see what kind of process I can use for both of them. Do you recommend something different for the cherry tree? When they first started bearing fruit, it wasn’t such a problem, now every single piece of fruit is affected. I I know that the fruit falls to the ground and sets up a whole new batch of fruit flies for the following year under the cherry tree. Although my husband, who teaches at Osu, cascades is a biologist and happily eats the fruit fly larva (just like a chimp!, )The rest of us are a little less enthusiastic about white maggots at the center of a ripe cherry. the apples are delicious but most people who aren’t familiar with the situation will not eat them, so I’m looking for a way to treat both trees so that we can enjoy the fruit more fully. I am committed to avoiding harming the pollinators. Thanks for the link and any additional information you might have.

Kathryn
Sent from my iPhone

On Jan 29, 2024, at 1:49 PM, Ask Extension <<personal data hidden>> wrote:

The Question Asker Replied January 31, 2024, 2:14 AM EST

Hi Kathryn,

Although unlikely, another fly consideration would be Spotted Wing Drosophilia (SWD). The SWD usually lays multiple eggs within the cherry and the larva full grown are 3mm whereas Western Cherry Fruit Fly usually has one larva per cherry and, as mentioned, are 8mm full grown.

Assuming it is the Western Cherry Fruit Fly, here are a couple links for more detailed information and management:

https://pnwhandbooks.org/insect/tree-fruit/cherry/cherry-western-cherry-fruit-fly

https://extension.usu.edu/pests/research/western-cherry-fruit-fly

Confirmation and first emergence could be achieved by using yellow sticky card as mentioned in the links. If you have a bird proof cage, putting the sticky card in it would help keep feathered friends and other critters from contacting it.

While insecticides are applied after the cherry tree blooms, there is the concern of the insecticide drifting onto nearby blooming plants/weeds; applying near dusk can minimize exposure to bees although some products can remain active for days.

In addition to removing and destroying dropped fruit, if possible, pick cherry trees clean to remove egg-laying sites for late-emerging flies. Perhaps some chickens could help reduce the larva population under the tree as well!

Hope this is helpful. Please feel free to reach out if you have any further questions!