Bitter Rot and Crinkled, discolored leaves on my Honey crisp apple tree.

Asked October 16, 2020, 9:01 AM EDT

We planted trees 3 years ago, only this year did the crinkled discolored leaves appear. And the few apples we got were deformed with what I believe to be Bitter Rot. Is there anything I can do to make this better? I need advice about when to prune, fertilize to see if maybe we are doing something wrong or not doing something we should be.

Oakland County Michigan

1 Response

The discolored leaves is a physiological disorder that does not bother the tree.

https://www.canr.msu.edu/news/honeycrisp_leaf_yellowing_showing_up_on_michigan_apples

Crinkling of leaves may be due to insect or perhaps a disease. I would need to see pictures to narrow this down.

Symptoms of bitter rot are fairly distinct--concentric rings, flattened lesion area, a cone-shaped rot inside the fruit that tapers toward the core. Rot can also be due to insect punctures, black rot, bird pecks.

Bitter rot persists in the tree over the winter in rotted fruit and dead twigs. In the spring do a thorough pruning job to remove this material. Also scan the tree post bloom for mummified fruit to remove. Fungicides for bitter rot include captan, mancozeb, Ziram, and Flint Extra. Probably the most useful and accessible for you will be captan. Mancozeb has a 76 days before harvest restriction. Fungicide sprays for this disease are needed during warm wet weather from late June until a few weeks before harvest.

For home apple grower sprays where you need to protect against insects, and diseases I recommend this short resource from the University of Kentucky https://plantpathology.ca.uky.edu/files/ppfs-fr-t-18.pdf

Here is a good resource on home fruit tree care - https://ag.purdue.edu/hla/pubs/Midwest_Home_Fruit_Production_Guide_940.pdf

They also have a good resource for pest control --https://www.extension.purdue.edu/extmedia/ID/ID-146-W.pdf