Help identifying Apple pest/disease

Asked June 17, 2020, 10:00 AM EDT

Can you identify what is on my apples? How do I correct it? Thanks

Livingston County Michigan

3 Responses

If you send a better picture with the surface of the apple in better focus I can be more sure about my diagnosis. This is probably one of the following: plum curculio injury or perhaps fruit infection by apple rust fungus. I can't really give you a management strategy until I am sure. Try putting a piece of cardboard or your hand behind the apple when taking the picture so that the camera is focusing at that level rather than focusing on the ground.

I’m not home and don’t have the Apple anymore. I don’t believe curculio as I know what that looks like. Before I contacted you I did some online research and I was leaning towards rust. The spots are a perfect circle and golden orange in color. There a some small bumps inside the circle. If it is rust what do I do?

Yes, I agree with you that it is a rust based on your description. You probably can find orange spots on leaves and other fruit. There are several rust types that can be found on apple. Spores that infected your apple tree came from infected juniper, cedar, or hawthorn trees in the vicinity. These ornamental trees are the alternate host. Infected apple trees provide the spores that infect the ornamental host, which in turn infects nearby apple trees.

Fungicide treatment starting when fruit are small can help to head off rust infections. These treatments are only preventative--they will not help fruit that have already been infected. Or you can find and eliminate the alternate hosts.