Friends are worried about their Acer palmatum ‘Beni Sazanami’ whose leaves look healthy and green on some branches but dried on others, together with dead branches (no green under the bark) and, at the same time, beautifully coloured fall leaves on most of the tree. They planted it about 4 years ago but it was quite large at the time. The thing that worries them the most is the development of blackening bark on many branches. Some we scratched show no green underneath. This has been an exceptionally dry summer here on Vancouver Island, BC and they worry that they may have over or underwatered it; personally I don't think so as it has fared pretty well up until now. I suggested to them that there's not really anything they can do but hope that it will bounce back in the spring. They're worriers though. Is there any consolation anyone can offer or do they have good reason to worry?
Hi Margot, IMO its time to remove the branches that are starting to fail, when they start to go black there is little hope in trying to save them. If not removed then the die back will continue. The one thing to tell your friends, is that maples will always lose some branches every year. so the three D's is impotant to remember. I think there is hope looking at the pics you posted. But it might look a bit unsightly after pruning until next year. Do tell them to use rubbing alcohol on the secateurs to ensure no spread of disease.
@Margot , As Derek mentioned, we would also cut all the sick ( black) limbs out right to the main stock and try to reshape at the same time. Once the limbs start dying there is no going back, stay ahead of the die back and cut back far enough to hopefully eliminate the spread
The black bark is on so many branches! The tree will look mutilated once they're gone. What is the disease? Do you know what caused it? This is one of several JMs they have planted in the back garden . . . is it contagious?
Hi Margot, die back can be from Verticulum wilt. Without seeing a cross section of a pruned branch it is difficlt to say tbh. If your friends can cut one of the branches and look at the cross section to see if there are black rings, then that will either confirm or rule out the problem. There is no cure for VW. maples can take several years to die, starting with signs of a general decline, half the tree looking fine, and the other half with dead branches and shrivelled leaves. The other thought though, is the extreme dry and hot Summer you have experienced there in BC. maples really don't like that at all and will react accordingly with lack of vigure with branhes dying back etc etc. So I think the next step is to advise them to prune to see a cross section and get a photo for forum members to take a look at. Sorry not more helpfull
Thank you for your suggestions and advice. I have been worrying about verticillium for a couple of years, starting with another JM a few yards away that had mysterious dead sections. After pruning, the tree is starting to look better. I will suggest doing the same with this tree and send photos as soon as I'm able.
Yes, I lost a beautiful JM to it many years ago. I thought it was interesting that another had died of apparently from the same fungus a year or two earlier in another garden 'upstream' from mine.
Maybe it's not as bad as verticillium, let's hope. There are so many pathogens, perhaps it's not as lethal. In any case, once the sick branches are pruned, I apply Bordeaux mix, I saved a lot of trees this way. "Nolite itaque amittere spem", never lose hope...
Thank you for the ray of hope. I'm going over tomorrow to try and help them determine whether or not verticillium is evident. Keeping my fingers crossed. At the very least, I will encourage them to use Bordeaux mix.