eXtension

Apple blemish and how to treat

Asked November 19, 2020, 4:11 PM EST

We have a six way espalier apple tree and noticed this year that many of the apples had a unusal blemish on them. After doing some research online, I think it may be a form of scab (pictures attached), but the skins don't appear to have the traditional bemishes seen from scab. Most of the leaves are off the tree and I have been raking and disposing of the leaf matter, but would like to know if this might require a dose of copper or other treatment. I know not to mix this with a dorman oil treatment. Any help would be appreciated..and thank you in advance.

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Multnomah County Oregon

3 Responses

Thank you for the images of your apples. The spots (slight depressions) are caused by one of two things: Bitter Pit or Stink Bug Damage.

To differentiate between them, please cut at least one apple vertically through the center of several spots, rather like cutting the apple in half, stem to blossom end.

Then, please send the following:
- one or two well-focused images of the cut surface
- ow long ago did you plant the tree
- details of how the tree was watered during the summer, including (1) what kind of system; (2) how often; and (3) how long each time.

I look forward to receiving the additional images, also the tree's irrigation history.

Hi Jean,
Thank you for the fast response.

Here are two images (in better focus) for your insight. In looking at the blemishes and skin depressions on our apples this year, I notice that there is a small black spot at the start of the depressions, that looks like a insect bite location.

The tree is over 10 years old, and has six different apple varieties on a disease resistant root stock. I'll see if I can find our documentation from when we bought it.

The tree was hand watered at the base during much of the summer (once a week), but when we got to the hot spells last year, we resorted to watering our entire garden (and the apple tree) via an overhead sprinkler once every two days (early in the morning) for about 10 minutes. This tree was on the far edge of the sprinklers watering pattern, so don't think it received an over abundance of water (less than my hand watering)
Thank you again for your help.
Bill



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Bill,

Thank you for the update. No need to locate your original records. The reason for asking how long you've had the tree is that recently planted fruit trees require several years to develop the sturdy root system needed to support abundant yields.

It appears that your thought about insect damage is correct. The browned interior tissue is quite deep into the flesh. That's in contrast to bitter pit which is immediately below the apple peel. (Bitter pit is a physiological disorder due to erratic soil moisture.)

The most common culprits for this sort of damage are Brown Marmorated Stink Bugs, Halyomorpha halys, sometimes referred to as BMSB.

Stink bugs may be a challenging problem to resolve unless you see numerous stink bugs on the fruits. (See "Brown Marmorated Stink Bug" -- http://ipm.ucanr.edu/pestalert/pabrownmarmorated.html)

Key ID characters:
- A white band on each antenna ("feeler") which is present during all life stages, the youngest to adults.
-The new hatchlings resemble red and black lady beetles, as in the attached image. (Image source: https://bugguide.net/node/view/885555/bgpage)
- Groups of eggs are typically on the undersides of leaves; crush the eggs whenever you see them.

Management seldom includes pesticides because BMSB are resistant to many products.

Vigilant gardeners can be successful with the following strategy:
- Flick the stinkbug into soapy water; repeat as needed.
- Protect fruits with floating row cover, ballooned around a fruiting branch.
- And/or protect individual fruits with a "footie" or small paper bag.

If you have further questions, please ask.







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