Malus ‘Spring Snow’ - Apple Scab? - Ask Extension
I have 3 Spring Snow Crab trees in my backyard now entering their 3rd or 4th year. One of the 3 is growing at a slower rate than the other two. I be...
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Malus ‘Spring Snow’ - Apple Scab? #829336
Asked May 10, 2023, 11:51 AM EDT
I have 3 Spring Snow Crab trees in my backyard now entering their 3rd or 4th year. One of the 3 is growing at a slower rate than the other two. I believe in part it may be because of a Cleveland Pear tree close by that was recently removed. I also noticed that the leaves on the smaller tree start dropping much sooner than the two and looks like it is struggling sometime mid to late July and into August. I have included a picture of the 3 trees along with leaves. I am wondering if Apple scab might be causing an issue, especially with the smaller one. Looking forward to your response. Thank you!!
Franklin County Ohio
Expert Response
It does appear that you have a potential fungal issue. Looking at the leaf, the photo doesn't seem wholly consistent with what I would expect with apple scab, but photos can be deceiving. Note, Spring Snow Crab are very susceptible to apple scab. See description below.
"Symptoms first appear in the spring as spots
(lesions) on the lower leaf surface, the side first
exposed to fungal spores as buds open. At first,
the lesions are usually small, velvety, olive green
in color, and have unclear margins. On some
crabapples, infections may be reddish in color. As
they age, the infections become darker and more
distinct in outline. Lesions may appear more
numerous closer to the mid-vein of the leaf. If
heavily infected, the leaf becomes distorted and drops early in the summer. Trees of highly susceptible varieties may be severely
defoliated by mid to late summer
Apple scab can be successfully managed by integrating resistant
varieties, cultural practices, and chemical or biological control.
https://www.forestcitytree.com/images/Scab-of-Apple-and-Crabapple1.pdf
More info on apple tree diseases:
https://hgic.clemson.edu/factsheet/apple-crabapple-diseases/
https://arbor-experts.com/common-crabapple-diseases-that-cause-summer-defoliation/
Looking at the site, it appears that the trees are not too crowded and the canopy is not too dense. So, I do not think pruning is needed. If you water the trees, always water at the base, not on the leaves (e.g., using a sprinkler). If you notice fungal spread on the leaves, you will likely need to start a chemical control using a fungicide.
https://cuyahoga.osu.edu/sites/cuyahoga/files/imce/Program_Pages/ANR/DigIn/Controlling%20Diseases%20and%20Insects%20in%20Home%20Fruit%20Plantings%2C%20Bulletin%20780%20%28whole%29.pdf
All the best, Roxanne
"Symptoms first appear in the spring as spots
(lesions) on the lower leaf surface, the side first
exposed to fungal spores as buds open. At first,
the lesions are usually small, velvety, olive green
in color, and have unclear margins. On some
crabapples, infections may be reddish in color. As
they age, the infections become darker and more
distinct in outline. Lesions may appear more
numerous closer to the mid-vein of the leaf. If
heavily infected, the leaf becomes distorted and drops early in the summer. Trees of highly susceptible varieties may be severely
defoliated by mid to late summer
Apple scab can be successfully managed by integrating resistant
varieties, cultural practices, and chemical or biological control.
https://www.forestcitytree.com/images/Scab-of-Apple-and-Crabapple1.pdf
More info on apple tree diseases:
https://hgic.clemson.edu/factsheet/apple-crabapple-diseases/
https://arbor-experts.com/common-crabapple-diseases-that-cause-summer-defoliation/
Looking at the site, it appears that the trees are not too crowded and the canopy is not too dense. So, I do not think pruning is needed. If you water the trees, always water at the base, not on the leaves (e.g., using a sprinkler). If you notice fungal spread on the leaves, you will likely need to start a chemical control using a fungicide.
https://cuyahoga.osu.edu/sites/cuyahoga/files/imce/Program_Pages/ANR/DigIn/Controlling%20Diseases%20and%20Insects%20in%20Home%20Fruit%20Plantings%2C%20Bulletin%20780%20%28whole%29.pdf
All the best, Roxanne
