Hi, It seems like at the moment I don't have much luck with some of my young maples. Both are in pots 1/ The Osakazuki seems to be subject to Powedered Mildew. It looks like people try one of the following treatments (or are they just preventive?): - hydrogen peroxide 3% - baking soda + water - diluted neem oil - copper sulfate - fungus fighter plus (for instance) Has anyone used any of these and got good success in getting rid of the mildew? Or is there any better option? 2/ The Oridino Nishiki that I got from a nursery not long ago and I think had the issue when I bought it (I should have checked more carefully). On the cut they made on the leading branch, there's a black zone, and on the branch a bit below that there's some darker zone. Do you think it is verticilium? Thank you for your help.
They are still in pot? I wouldn't care about mildew. There's always next year. Maybe spray a fungicide against it to strengthen the plant a bit (i.e. not further weaken it). The second picture... that's indeed a sign of vertilicilium, but if its a young tree... its been in a pot for all its life? So that would mean I guess it would have wound up in the pot, which seems quite unlikely... but not impossible. The spores can spread... I guess wait and see, and keep this tree away from others for the time being.
@Riverdale27 , thank you. Yes, there are still in pots as I got them not long ago. I bought the one with verticilium several weeks ago. I don't know how the nursery or the grower they got it from grew it. I should have paid more attention :( Actually I got two of these (as they were clearing their outdoor stock, and reduced them to £5 each - instead of £10). I've just checked the second one, and the second one has got a similar black spot on a similar cut...
Instead of verticillium, I suggest pseudomonas syringae (bacterium). Hydrogen peroxide, being an antiseptic could be effective, but copper based fungicides, including bordeaux mix (copper sulfate in lime sulfur) are more frequently used as these have residual action whereas peroxide only nixes what is laying around at the time it is sprayed. Phyton 27 is said to have systemic activity and might cure the infection with out or with less further pruning. I've not had occasion to use it, but it is the manufacturer's claim. btw, 3% peroxide is a bit hot. It is effective and nondamaging on plants at concentrations of 300 ppm to 1k ppm. Regardless, it doesn't have much effect on downy mildew in my experience.
