Apple tree disease

Asked May 25, 2020, 10:08 PM EDT

i have a new small orchard of 125 fruit trees in gales creek. many of my apple trees have a dark grey rust like blight. Picture below. My Pink Lady apples have it the worst. What should I spray this with?

Washington County Oregon

1 Response

Thanks for your question.

When did you first notice the symptoms on the leaves?

It's hard for me to tell what the injury is from the photo.

Pink Lady apples are very susceptible to apple scab which is a prevalent disease on apples in Western Oregon.

The PNW Pest Management Handbook has details on the symptoms of apple scab. Check to see if there match what you're seeing in the orchard. https://pnwhandbooks.org/plantdisease/host-disease/apple-malus-spp-scab Look in the bottom sections on cultural and chemical control for options on managing the disease.

Washington State University has a fact sheet on Apple Scab with descriptions on the pathogen and disease cycle along with control options.

Purdue University has a publication on the Disease Susceptibility of Common Apple Cultivars https://www.extension.purdue.edu/extmedia/BP/BP-132-W.pdf. Have a look at the table to see varieties that are less susceptible to apple scab.

If the symptoms do match the description for apple scab, please higher resolution photos of the leaf damage.