What causes the brown veining on Ida Red apples

Asked August 17, 2020, 11:21 AM EDT

County resident spays trees with ortho's orchard spray. he has an ida red tree and a honeycrisp tree. the honeycrisp does not exhibit this issue on it's apples but the the ida red does. He said that the leaves do not have spots on them. My impression was that it was Apple scab with a touch of apple maggot activity, but wanted a better set of eyes with more knowledge to give me their impression of what the issue might be.

Tuscola County Michigan

2 Responses

The net-like russeting is likely from powdery mildew. Ida Red is really quite susceptible to it - more so than Honeycrisp, but they can both get it. The warm weather during bloom in 2020 was very conducive for mildew. The indentation is likely from green fruit worm or leafroller feeding early in the fruit development. The larvae takes a bite, kills the tissue, but the rest of the apple continues to grow around it, leaving a pit. The hole above that pit appears to be from first generation codling moth, back in late May or early June.
I don't see evidence of apple scab or apple maggot in this picture.
The combination sprays are good for homeowners to use, but they sometimes get stretched out too long for the seasonal weather conditions. And, you can't use them at any time during bloom because they have an insecticide in them, BUT, in MI springs, we often need a fungicide or two during a hot and humid bloom for mildew.

Thank you Amy. I knew I was not going down the correct path when I thought scab. I did not know what could causing the russeting.