How to Control Sooty Blotch and Flyspeck on Apples

Imagine this scenario with me: you’re examining your fruit trees, several that you’ve been growing for years.

Much to your horror, most of your apples have come down with evil looking sooty blotches that may coalesce to cover the entire fruit, or specks that look like fly excreta.

Extension agents frequently receive panicked questions about these symptoms.

But there’s good news! You can rest assured that your fruit will be fine, and these blemishes are just cosmetic. In fact, you can actually rub off a lot of them, like a ding in the shiny new paint job on your car.

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This is fine if you will just be making apple sauce or apple butter with them, but what if you want to sell your apples?

We will give you tips on how to prevent these diseases from plaguing your trees, and what to do if they do occur.

First, it’s important to understand that these symptoms are due to the activities of two different diseases. Sooty blotch is caused by several different types of fungi, while flyspeck is caused by the fungus Zygophiala jamaicensis.

These two diseases are usually grouped together because they often occur on fruit together, and are controlled the same way.

Flyspeck manifests as clusters of 6-50 black, shiny, slightly raised round dots. Sooty blotch is as it sounds –­ dark blotches that may cover most of your apples.

One thing to remember if your tree is prone to this problem is that the symptoms look a lot worse on light-colored fruit. Particularly if you are selling your apples, you might want to consider growing red-skinned