Anyone recognize the small, dark spots on a Goldrush leaf? It’s on every leaf on the tree, only tree in the orchard with it. It has defoliated much of the tree, needs prevention next year.
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I’m not sure, but it looks a lot like what I’ve been seeing with trees that appear to be dealing with this:
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Good question. My Goldrush has the same looking thing, as does Ashmeads Kernel to some extent. I presumed that is something CAR related but truthfully I have no idea.
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@JinMA I think you nailed it. I’ve never heard of Marssonina leaf blotch. This is on a friend’s partially defoliated Goldrush. He planned to spray a copper soap next spring as he is organic only, but from the article Alan posted looks like June is time to spray. I don’t see an organic solution recommended beyond sanitation: rake up all leaves in fall. What about Bordeaux mixture starting in June??? Definitely not just cosmetic here, causing early defoliation.
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In terms of solutions, I wish I knew! I’ll be looking into different options for sure. For the moment, I’m stripping and composting heavily affected leaves pretty much on a daily basis. (I have small trees, so it’s not that hard.) Hopefully that’s reducing the impact somewhat.
Somehow, I am concerned about composting affected leaves so I have thrown them out with trash. I may not be rational.
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You are right Mamuang, diseased plant parts should not be composted. They should be either burned or thrown in trash, so that they don’t make their way to the orchard.
I don’t claim to be an expert, but as I understand it, subjecting infected leaves to processes that accelerate decomposition can significantly reduce some kinds of disease problems, notably apple scab. See for example the discussion of leaf shredding in this article:
The interesting thing about leaf shredding is that the infected leaves aren’t even removed from the orchard, they’re simply shredded to accelerate decomposition.
Speaking for myself, what I’ve read about sanitation for scab makes me feel pretty comfortable composting the leaves.
How well sanitation will work for Marssonina is another question, of course.
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Here’s a study testing organic prevention of MLB:Progress report for FNE20-957 – SARE Grant Management System
Their preliminary finding is that Oxidate 2.0 works, product description here:https://www.growingproduce.com/fruits/oxidate-2-0-labeled-for-fire-blight-in-apples/
Looks like an off label use of a fireblight treatment. Fireblight is bacterial though, right? I thought MLB is fungal. Must be broad spectrum to take out both.
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Go to topic New apple disease in the northeast. I posted a link that suggests fungicides to use, including organic acceptable ones.
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