Hello all! Super new here, first post. I recently picked up a bunch of Japanese Maples (26) and some appear to be in poor condition, many have possible sun scorch - white spots, burns on leaf edge. I am hoping someone can give insight as to how to bring this particular tree back to it’s full beauty. My husband read about Super thrive so we picked that up. This tree has lots of bald spots, lots of dead and wilted leaves, white spots and burns that appear to be sun scorch but I could be wrong. It has been in a pot for who knows how long and the soil seems to be clay heavy. We have rocky soil here but with this looking so sickly I wasn’t sure about planting it. I have other JM’s that have black branches, starting at the tip and moving down. That is on a Katsura JM. If I figure out how to post pictures of that I will, or of any other tree with concerns. Any and all advice is welcome! Thanks!
Hi Arin, Well I can see quite a lot of people have seen your post but not responded yet, so I'll make a start! Yes the white spots look like sun or wind, they are aesthetic only and nothing to worry about for now. What you describe on your 'Katsura' sounds like either pseudomonas infection from the winter or too much water, or actual verticillium wilt. What I see in your pictures here looks like it might also be verticillium. Verticillium is not necessarily a death sentence for the tree, but like any long-term illness it requires management. Stress to the plant will bring on attacks. I think you were right not to plant this, but I don't think you have any choice about transplanting into different soil. This is a stress but I guess it will benefit from it judging from how you describe the soil. The overall idea is to let the tree convalesce for a couple of years before you plant it in the ground, so it has its strength up for that transition. I would proceed as follows. Hopefully someone will chime in with what I've missed or they disagree with. We have several posters here, who are more expert than I at keeping maples in pots. 1. Cut back all dead (white or gray) and blackened or stained growth to clean wood. Disinfect your secateurs with rubbing alcohol or bleach solution between each cut. (Very important!). Cut a couple of cms into the clean wood where possible. Be prepared to take off whatever is necessary. 2. Spray the entire tree with atomized copper solution (Bordeaux Mix). People in the US recommend Phyton27 for this but there are other options. 3. Evaluate the roots. Disentangle them, get the old soil off -- wash if required -- and perform a light root pruning. Some may disagree but I think a heavy pruning would probably add more stress, so I'd rather increase the pot size. You could post pictures of the roots (before cleaning) for some more advice on this part. 4. Replant in very free-draining soil with just a little fertilizer. Don't buy any pre-fertilized soil. Potting soil is a big thing (search the site) but if you're anywhere near the wet coast, you'll want something that dries relatively quickly. Water the tree in well. You can use the superthrive at this point. Try not to use tap water. 5. Put the pot in a mostly shady (a couple hours morning sun is good) place that is well protected from wind. Don't over-water: make sure the pot has a chance to dry out before adding more; as the tree is recuperating you want root growth. Hopefully in 3-4 weeks you will get new buds and leaves. This new growth will encourage the roots, installing a virtuous cycle. 6. Continue to spray with the copper every 3 weeks, and several times over winter. Make sure you don't leave the pot out in the wet during the dormant season. No more fertilizer until another light dose in spring 2020. If you see more blackening, remove it and spray. (Note the copper won't help with the verticillium if that's the fundamental problem, but it will help with associated fungal or bacterial infections the occur in the wounded areas.) Good luck, and with luck someone else will chime in. -E
In the event this is the verticillium, does that mean that the soil it’s been sitting on in the pot is now contaminated with that? We really had hoped to plant a spectacular centerpiece in that location as it’s right outside our front door. If the soil below the pot is now infected, what can I do?
Verticillium is present in all soil, in greater or lesser concentrations. I'm not from the school that believes you shouldn't replant a maple in a spot that had a plant attacked by v. wilt, but opinions certainly vary on the question. If you wash the roots you should be OK anyway, but it's an open question as to whether you want to plant something that already has v. in such a spot. Still, it's by no means sure that that's what the problem is, just a guess on my part, so you can only wait and see what happens after going through the process.
That’s interesting to know that it is pretty much everywhere. I have an existing tree (came with the house) that I suspect also has the wilt. I’m concerned as I just bought 29 trees from this person, it’s a nursery going out of business and I’m wondering if I just wasted all that money. I really appreciate the informta
