Good morning!
I'm a new member as of this morning. My name is Sara and I live in Michigan, in Zone 5B. My husband and I bought our home about 3 years ago and inherited an overgrown home orchard on the property. I am just this year turning my attention to the orchard. I'd love to bring it back under control, producing some healthy, delicious, organic fruit. We have about 18-20 trees - mostly apples and pears.
I did a pretty major dormant season pruning this winter, trying to get the trees down to a more manageable size and opening them up to allow for ample air (and light) circulation. Now I'm trying to tackle the pests and diseases.
I'm having trouble identifying this disease. I thought it was scab, but haven't been able to find any photos of scab on the bark of apple trees, only on the fruit and leaves. I was hoping someone here would know what this is? Also, any suggestions you have for combatting it would be greatly appreciated! I'm trying to use only organic and sustainable methods.
I can't get the pictures to show up in the post, but here is the link to the pictures on Flickr: .
Thanks so much, in advance!
Sara
I agree with Marsha, they look like ‘ordinary’ lichens. I suspect dormant sprays of liquid lime sulfur would kill them. It’s too late for a strong enough dose this year, as the trees have budded and the leaves would burn. But honestly, I don’t think lichens are much of a problem…
From Ohio State: “The following is a brief description of some disease control materials that are commonly or traditionally used in organic production systems. Copper fungicides, elemental sulfur and liquid lime sulfur are the old “standard†fungicides, and have been used for many years in organic production systems.â€
The lime sulfur would also kill moss, another plant. But there again - you’d best wait until next winter. It’s ‘organic,’ but leaves your branches smelling of rotten eggs… something that makes pruning less fun 
I think you two are right about the lichens. Looks just like the lichens that came up in my google image search just now. I'm glad to hear they don't seem to really be a problem for the trees, too. Maybe I will try a lime sulfur spray next winter. Or just let them be if they won't harm the trees/fruit.
Thanks so much for your helpful replies, Marsha and Viron!
Sara
Lichens are not a parasite, meaning they do not harm the tree or fruiting of the tree. I would not recommend spraying for that reason, Lime sulfur is a anti-fungal. Apple scab for instance is a fungal problem that Lime sulfur would take care of. Check with you extension agent for local problems and spray recommendations.
Randy
Yamhill County Master Gardener
Idyllwild
simplepress
jafar
Marsha H
Viron
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