I have a shimpaku forest that seems to have two different issues. One looks like blight and the other possibly rust? 7 trees total.
Two trees in the back of the forest have spots turning a rusty color.
Two trees in the front are turning yellow, and becoming brittle. I’ve pinched and brushed as much of the brittle foliage off as would come off easily.
Thoughts?
Causes?
Cures?
Unfortunately have not been able to find any mancozeb, and Amazon will not ship it to Washington state. I did order another fungicide that is copper based.
Thanks in advance!
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I would love to get some insight too. Usually in the spring I spray with insecticidal soap which seems to keep things under control. This year, I also tried a copper fungicide which didn’t seem to help much, but that’s not to say it won’t work for you.
My issues are probably different, but a lot of my trees look like the third and fourth photo in your first post.
Maryann
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Hi David, have you solved the problem? It’s a bit hard to tell from the photos but you may have spider mites which can cause yellowing foliage.
From the photos the branch with some browning foliage has been wired, perhaps (and please take this with a pinch of salt) you may have damaged it in the wiring process.
Other reasons for yellowing foliage is sudden exposure to light, weak to start with, or the tree simply not needing it anymore.
Can you post a photo update? cheers
I think I would agree with the red spider mite diagnosis. Insecticidal soap should keep things under control and it’s a pretty benign insecticide.
Actually Ryan covered this question on the last forum Q&A.
The foliage that is rusty did not die. It was very much still transpiring water, and I definitely do not think it was damaged or broken. He thought it could be fungal issue, but is tough to say without testing. I ended up cutting the diseased parts off, and I’m monitoring the situation.
Ryan thought the yellowing foliage was just the trees choosing to lose those parts. I’m not in full agreement just yet. I have tested for spider mites a few times over the spring and summer, and I have not been able to spot any, so maybe Ryan’s diagnosis is legit (who am I not to trust his judgement, haha). It just feels like something wrong.
I have been using Zerotol 2.0 on my junipers for similar looking foliage and I think it helps. This was based upon a recommendation to one of our club members a few years ago, I believe by Michael Hagedorn, but it could have been someone else. It is an organic peroxide and I do keep it mixed in a spay bottle between uses. Biggest issue is that it is primarily available in larger containers that are not inexpensive, but I am using from a quart that I bought from the club member.
