honeycrisp apple leaves

Question: my tree is approximately 4 1/2 years old. this summer some of the leaves started to turn pale yellow with brown spots along the edges. I would appreciate any ideas as to the problem if in fact there is one.  thank you

responder: Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 19, 2023, 6:36 PM EDT
response: Yellowing leaves, leaf spots and blotches can be symptoms of a few different things, so I will need a little more information, and would like to see a photo of the whole tree, if possible, so I can see the distribution of the symptoms. How often do you water the tree during the summer? Do you fertilizer? Is this a honeycrisp apple? If not, what variety? Are there any symptoms on the branches or fruit (and did the tree bloom and produce fruit)? Do the spots appear on the bottom of the leaf or just the upper side?

responder: The Question Asker Replied July 20, 2023, 4:53 PM EDT
response: In answer to #0111100.  Water once a week if dry.  I put a small amount of 16-16-16 around the trunk and water in well. It is a Honeycrisp. No symptoms on branches or fruit. It did bloom and produce fruit. The spots seem like they are on top of the leaf.   Thank you for your time

responder: Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 20, 2023, 5:51 PM EDT
response: This looks like Honeycrisp leaf mottle disorder, which causes chlorosis in the leaves. It is a disorder that is specific to Honeycrisp apples, particularly young trees that aren’t producing a lot of fruit. It is caused by an accumulation of carbohydrates in the leaves which reduces photosynthesis and causes the leaves to turn yellow. The good news is that it will not affect the quality of the fruit, and no treatment is necessary. The issue should go away as the tree matures and produces more fruit.   I will note, insufficient watering, lack of fertilization, or iron interveinal chlorosis can cause similar symptoms, but based on the information you provided and the yellow and green patchwork-like blotches I see in the photos, I think this is Honeycrisp leaf mottling.   For more information on Honeycrisp leaf mottling, refer to the following: https://www.canr.msu.edu/news/honeycrisp_leaf_yellowing_showing_up_on_michigan_apples and https://www.ag.ndsu.edu/smallgrainS/Dr-apple-tree/leaves/honeycrisp-leaf-mottling

responder: The Question Asker Replied July 20, 2023, 6:07 PM EDT
response: In answer to #0111100.  Water once a week if dry.  I put a small amount of 16-16-16 around the trunk and water in well. It is a Honeycrisp. No symptoms on branches or fruit. It did bloom and produce fruit. The spots seem like they are on top of the leaf.   Thank you for your time

responder: Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied July 20, 2023, 6:09 PM EDT
response: This looks like Honeycrisp leaf mottle disorder, which causes chlorosis in the leaves. It is a disorder that is specific to Honeycrisp apples, particularly young trees that aren’t producing a lot of fruit. It is caused by an accumulation of carbohydrates in the leaves which reduces photosynthesis and causes the leaves to turn yellow. The good news is that it will not affect the quality of the fruit, and no treatment is necessary. The issue should go away as the tree matures and produces more fruit.  I will note, insufficient watering, lack of fertilization, or iron interveinal chlorosis can cause similar symptoms, but based on the information you provided and the yellow and green patchwork-like blotches I see in the photos, I think this is Honeycrisp leaf mottling.  For more information on Honeycrisp leaf mottling, refer to the following: https://www.canr.msu.edu/news/honeycrisp_leaf_yellowing_showing_up_on_michigan_apples  and https://www.ag.ndsu.edu/smallgrainS/Dr-apple-tree/leaves/honeycrisp-leaf-mottling.