I have an acer cir SUNGLOW which has developed some mildew. I assume I should move the plant into greater air circulation and maybe more sun? How do I do this in a gradual way so I don't burn the non-mildewed leaves?
katsura, Treat the mildew with a fungicide. In winter transplant the maple to a more favourable position. The new spring foliage should grow and acclimatise to the new location. Good luck.
I just got a small 1gal Sun Glow that came with mildew. The grower offered not to ship it but, since it was the only one, I felt it would be no problem an took it anyway. This tree may be a little more suseptible to mildew so a planting location with good air circulation and adequate sun will be important. I treated with a fungicide that quickly resolved the issue and I am keeping the pant in mostly shady open area. The mildewed leaves have fallen and I am getting beautiful new growth. In a tree as sensitive as Sun Glow, even a mild case of mildew will most likely equal the loss of foliage. If you continue to have problems with this plant, you will need to take prevetative treatment precautions in the future. I regularly have mildew problems with my Beni komachi and sometimes Kiyohime and if I think about it, I will treat them preventatively. The spring foliage on my two 1gal Abigail Rose plants has been almost entirely destroyed by mildew and I am not sure how to control it on this plant. By far the most suseptible maple to mildew I have ever seen. Michael
I had never seen mildew on maples before, but this year the Willamette Valley has seen a very long, cool, damp spring and it is rampant in my greenhouse. The bad thing about mildew is that it's easy to get in cool, damp, still situations, but the good thing is that it succumbs to the mildest of fungicides. For my own situation, improved air circulation in the greenhouse has been the best treatment following a little spraying. It does seem that the circinatum are much more susceptible than most of the palmatum. susan
Outdoors fully exposed street trees, esp. Crimson Sentry Norway maples, as well as wild bigleaf maples can be seen with copious mildew. So much for air circulation. Mildew comes on in summer because it is favored by dry soil plus damp (but not wet) foliage, making the Pacific Slope perfect for it. Frequent washing of affected plants (outdoors) can actually interfere with it a bit, both by making the leaves too wet and re-moistening the soil. Some mildew spores have their own little droplet of moisture, so they can establish on dry leaf surfaces. I bought a 'Mocha Rose' bigleaf maple in spring leaf, on impulse this past spring. What a mistake! The attractive spring leaves have given way to these tattered, dirty amber, heavily mildewed eyesores that look like they are going to remain that way most of summer.
Hi Katsura, I'm experiencing some powdery mildew too down here in Los Angeles. I've read that hot days coupled with cool nights are ripe conditions for powdery mildew. We've been getting the "June gloom" here...the marine layer comes in at night and remains in the morning, followed by being burned off by the afternoon sun, but leaving behind hot, humid air. Ironically the mildew is on two of the sun/heat/wind tolerant maples...the Mystery Maple I wrote about earlier and the Itami nebluki (aka, Itami Nishiki). The Mystery maple has it only on a couple tender new leaves on first year wood. The Itami nebluki has it mostly on new leaves, but also on some older leaves. The mildew isn't rampant and doesn't seem to be spreading across the leaves or to other leaves. So, I'm atributing this to the new leaves' tenderness. I've had bad luck with spraying leaves for mildew or bugs. Most organics or chemical sprays coat the leaves with either oil or chemicals and then the sprayed leaf whithers any way...at least they have for me. I haven't tried copper based fungicides yet, though I've been advised to as it's the best remedy. However, I'm afraid to after reading the precautionary statements on the label! It's not much but that's my 2 cents... Layne
