Hi all, I was looking at some of my japanese maples - who doesn't? ;) - and I noticed lots of brown spots on many leaves on two of them. In particular, on one, there s a branch that seems really contaminated. I've attached photos of the branch (2 first ones), and the other 2 photos correspond to other places in the tree. The last two photos are of the second maple. The two trees are not next to each other - Are they fungal leaf spots (like Phyllosticta) ? Or do you think it could be something else? - Do I need to treat the trees now, or it will go away once the leaves fall down in autumn? - If it needs treatment, shall I just apply a fungicide, or/and also for the branch that is severely affected to be cut? Thank you Cheers, - Chris Edit: I've added photos of a second maple as it had similar issues
It could also be a bacterial infection, or at least I did not see anything in the pictures to rule this out and 100% confirm a fungal infection. It is worth checking the undersides of the leaves for fungal growth. Either way my approach would be wait and see. It would be good practice to dispose of the leaves off-site when they eventually fall but otherwise leave it be. Some would suggest spraying but I have never done this and trees with funky leaves have come back normal the next year. If any twigs turn black and die back they should be pruned out (would likely be Pseudomonas bacteria).
Thank you @maf I have checked twigs, and they do not look black. The infection seems to be in most parts of the tree, and on the outer leaves. I don't think I have seen any on the leaves that are further inside the tree. What do you check for on the undersides of the leaves for fungal growth? Thank you
Some fungal diseases (not all) will have pustules, spores or fruiting bodies etc on the underside of leaves where a necrotic spot is apparent on the top surface. It will generally have some sort of texture that is different from leaf tissue, colour can vary. If there is anything there it can be helpful in identification. To be honest, I would not worry too much at this late stage of the year. Leaves on many maples will be looking beaten up right now and are nearing the end of their lifespan.
Thank you! Having more trees this year, I got more problems (pseudomonas etc), at least I am learning thanks to you all :)
