Hi, Trista.

Thank you for contacting us with your question about your apple tree. I’m sorry you are experiencing problems. The photos you provided were very helpful!

It does appear to be powdery mildew. Some apple varieties are more susceptible to powdery mildew, such as, Jonathan, Granny Smith, Mutsu (Crispin), Rome, Cortland, Baldwin, Monroe and Idared. It is good that you noticed it now, so it can be managed early.

It is very likely your tree had powdery mildew last year and has overwintered and is redeveloping again. The fungus spreads rapidly to twigs, which stop growing and become stunted. In some cases, the twigs may be killed back. Leaves and blossoms from infected buds will be diseased when they open the next spring.

Below is a link to a fact sheet related to powdery mildew causes and cycle in susceptible apple trees.

https://ohioline.osu.edu/factsheet/plpath-fru-21#:~:text=Powdery%20mildew%20may%20be%20found,were%20infected%20the%20previous%20season.

To manage powdery mildew, it is important to prune and destroy infected white-covered twigs now while your tree is still fairly dormant. Bag the debris, do not compost it as the fungi will spread into the compost. Be sure to sanitize your pruning tools after each use to prevent spreading the fungi to other parts of the tree.

Also recommended, apply a fungicide or biopesticide specifically for treating powdery mildew on apple trees. Treatment can begin when buds just start to open (green tip stage), but before blossoms start to show pink.

Please refer to the link below for recommendations (Page 4, Tables 2 and 3). Please be sure to follow the instructions on the label for proper and safe application of the product you select.

https://bpb-us-w2.wpmucdn.com/u.osu.edu/dist/b/28945/files/2017/11/Disease-Management-in-Home-Apple-Plantings-1-18-FINAL-2gby8kt.pdf

I hope this information is helpful to you. If you have further questions, please feel free to contact us again. Good luck with your apple tree!