I've recently noticed an area of general leaf desiccation on the north side of a Crimson Queen. The tree is nestled into a southeastern exposure near the house and has been there for about 3 or 4 years. It's about 3' high and has about a 6' diameter canopy. The tree's tendency is to develop most of it's new growth away from the house. And, it's pushing some new leaves right now during the second-growth spurt of late summer. But, the leaves on the north side are drying up and falling off. In addition, there are nasty spider webs entombing clusters of these dying leaves. It looks as if the damage is restricted to the foliage. The underlying scions and branches appear to still be healthy. Nonetheless, I am concerned by this development as I've never seen anything like this before and none of my other maples are exhibiting similar symptoms. This does not have the look and feel of general heat/sun stress or fertilizer burn. The leaves deteriorated uniformly from healthy to dry and dead without any of the normal margin scorching that ones sees from these types of leaf problems. And, they've done so in the course of a week to ten days. I've examined the tree for some sort of insect attack (the webs seem to indicate some sort of activity in this arena), but haven't been able to see anything. Of course, these old eyes aren't what they used to be :( I would appreciate any insight or theories as to what the problem might be and, of course, what to do about it, if anything. Thanks, Bryan
Hi, I don't know and you didn't indicate how close your tree is to the house but, Japanese maples can suffer from heat reflected off a wall if it's planted too close to it. From your description this is what it sounds like...all new growth coming out away from the wall and the leaves drying up near the wall. That's my best guess. As far as the spider webs are concerned it's not the cause of the leaves dropping. Actually it's a reaction to it in a way. Spiders have an easier time making their webs between bare branches rather than between wind blown leaves. Layne
Pure guess, Bryan, but could it be spider mites. Webs and leaf dessication make me guess that. Mites are too small to be seen clearly with naked eye, so hold a sheet of white paper under a leaf and tap the stem sharply; any mites will tumble onto the paper and move around. Good luck.
Spiders build webs to trap and eat insects, other invertebrates (except in tropical rain forests where they also devour vertebrates!). Plants are just a platform for them and their activities, which benefit humans (as do those of other predators). Japanese maples are prone to various pathogenic organisms that cause them to blight off, if you are sure it is not physiological leaf burn it would not be unusual for it to be another problem. "Fungal" dieback of Japanese maples has become so common in my area these very popular trees are now being considered not such a choice addition to the garden by some. Sloppy practices in certain wholesale nurseries have been blamed.
Reading kats comments suggesting that the varmints might actually be too small to see with the naked eye reminded me of the fact that my youngest has one of those Digital Blue microscopes hooked up to our computer. I spent a few minutes scanning the surface of a leaf or two and found what appears to be telltale signs of some sort of insect infestation. There were colonies of what looked like exoskeleton remains. I only managed to find one that looked like he was alive. The bug shown in the attached picture wandered across the screen and I managed to get a snapshot of him. This picture was taken at 200X magnification. I know its not that great of a picture, but does anyone recognize this guy? Thanks, Bryan
I'm guessing it's one of these in a pre-adult stage: http://www.uky.edu/Ag/Entomology/entfacts/trees/2spotmit.gif Further described at http://www.uky.edu/Ag/Entomology/entfacts/trees/ef438.htm. The references to the webbing that these mites spin is one of the attributes that I'm focused on. Additional text that seems to be pertinent: I've been setting a sprinkler underneath the tree to wet the underside of the leaves. In addition, our weather has really cooled down in the last couple of weeks. As a result, further damage has been very limited. Bryan
