Knowledgebase

Treatment for apple maggots #796046

Asked June 15, 2022, 9:35 AM EDT

We are in Brooklyn Park. Last year these spots developed later in the year when the apples were about golf ball size. Since the tree was smaller and there were only 40 apples I powdered them individually with Sevin. The spots and dimples remained but the apples were very solid with white flesh and no evidence inside the apple. I sprayed this spring as advised right before the buds opened and then put the sticky trap in the tree. Yesterday I noticed these spots again and am hoping for advice on next steps. Your page indicates that the flies normally are active in July so I am unsure of how to proceed. Thank you.

Hennepin County Minnesota

Expert Response

Blister Spot is a fungal disease that causes raised brown blisters (4-5 mm) with a purplish black margin associated with the lenticels on the apple surface. The first spots are often found near the calyx end of fruit growing towards the outside of the tree facing the sun. Please read about this
http://www.omafra.gov.on.ca/english/crops/hort/news/orchnews/2014/on-0814a7.htm

http://www.omafra.gov.on.ca/IPM/english/apples/diseases-and-disorders/blister-spot.ht
I am including other information on how to prevent other problems.
https://hortnews.extension.iastate.edu/faq/there-are-black-spots-surface-my-apples-can-i-eat-skins

Thin the apples

To balance your production for next year thin the apple trees so only one fruit for about every 6 inches of branch.When choosing which fruit to leave, look for the largest fruit. Fruit that is small or damaged should be dropped first. Thin fruit before each apple reaches the size of a dime in diameter. This usually occurs within the first 20 days after petal fall. Removing these small fruit early will keep energy available for the fruit that remain and for fruit bud development for next year.
https://extension.oregonstate.edu/gardening/berries-fruit/fruit-thinning

Bag the apples

Enclose each apple in a plastic sandwich bag, either a zipper closure bag or a plain bag closed with staples.Snip the bottom corners off each bag with a pair of scissors to leave a small opening for water to run out.At harvest, remove the bag.

https://apps.extension.umn.edu/garden/diagnose/plant/fruit/apple/fruitspots/fruitsbs.html
https://extension.umn.edu/fruit/growing-apples
https://hort.extension.wisc.edu/articles/apple-maggot-scourge-of-home-apple-production/


Pat M MN master gardener and TCA Replied June 15, 2022, 11:21 AM EDT
We think the holes might have been made by plum or apple curculios.
https://content.ces.ncsu.edu/plum-curculio
https://www.plantwise.org/knowledgebank/datasheet/52616

We can’t tell whether a larva is present, but there might be one in the white spot seen here:
An Ask Extension Expert Replied June 20, 2022, 10:52 PM EDT
Thank you.


On Mon, Jun 20, 2022 at 9:52 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied June 21, 2022, 8:16 AM EDT
After taking another look, we need to add that the apple cross section may show early stage damage by a coddling moth larva.  The larvae mostly feed in the core but they sometimes enter elsewhere producing spots called codling moth stings.  Compare here:
https://images.app.goo.gl/qLU9boGccmQvuMtH8

https://www2.ipm.ucanr.edu/agriculture/apple/Codling-moth/
An Ask Extension Expert Replied June 23, 2022, 10:09 PM EDT
This is the current status of about 1/2 of my apples.  More advise please?

image
image


On Thu, Jun 23, 2022 at 9:09 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 13, 2022, 11:41 AM EDT

Coddling moth larva (Cydia pomonella) and Apple maggot (Rhagoletis pomonella) are prevented with esfenvalerate, carbaryl and spinosad. Once the larvae enter the apples, they are protected
https://extension.umn.edu/yard-and-garden-insects/apple-maggot  https://dl.icdst.org/pdfs/files/5d3bf0ca358f83df12d2c617e9d7883c.pdf https://extension.umn.edu/yard-and-garden-insects/codling-moths
Pat M MN master gardener and TCA Replied July 13, 2022, 12:21 PM EDT

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