We have had a Coral Bark Maple for 6-7 yrs. now and we have had to cut out dead or black growth. I have been told that these maple are prone to this fungus? We have been able to prune out the blackened stems as we see them and control it to a degree, but I think that we may end up losing it this year. I have been told that they are now grafting this particular maple on a different root stock, and have seen them at nurseries and the lower graft is green and then the red stem above it. Wondering if these are not prone this fungus or just less prone than what we have? Any information would be appreciated.
Hello, If the die-back and blackening you see happens during the summer, you most likely have a tree that is suffering from verticillium wilt. Unfortunately there is not treatment, and most of us have trees in the state you describe. I currently have 3 cultivars of A. palmatum -- including a Sango kaku -- in this reductive state. You're right that if the pathogen keeps coming back year after year we are eventually left with nothing. There's no treatment, all we can do is try to reduce stress. Make sure the soil is draining freely, but that it's getting enough water. Some recommend a light feed. The grafting issue is a bit of a red herring, except in that there is a problem currently with root stock being infected with verticillium; this of course dooms the tree eventually. But japanese maple cultivars are almost always -- and have been -- propagated by grafting onto generic A. palmatum (the species) root stock. In this way we guarantee the genetic identity of the cultivar. Cuttings are notoriously difficult with this plant and layering not efficient for commercial purposes.
Twig die back is common with this trree due to it's vigor. "The original Coral Bark Maple, and by far the most widespread, is the cultivar 'Sango Kaku', perhaps meaning "coral-painted". It's a vigorous and tall tree for a Japanese maple, growing to about 30'. The only rap on it is that, in cold-winter climates, it may be prone to some twig dieback, most likely due to its vigor; young twigs don't have time to ripen before winter. However, as you can see from the following photos showing its fall color, this doesn't prevent 'Sango Kaku' from becoming a majestic tree."
Yes, it is prone to winter die back. I inferred this is not what the OP was seeing as I thought his tree was diminishing year by year. Regular tip die back, which many maples experience, won't do that. Where is the quote from? I thought "Sango kaku" meant "coral tower." I also thought Senkaki was an older coral barked cultivar, now sunk into synonymy with Sango kaku. Even more, SK is prone to die back in warm winter climates, too, and is well known to be one of the problematic palmatums to grow. Its beauty makes us keep trying, of course! -E
That's correct, E.; Sango kaku means "coral tower". I have 3 SK (5 to 6 ft tall) planted in ground and one in 10 gal pot (6 ft). All of them are doing nicely, even with the hot/humid weather here. However, it seems that SK likes full sun. I have two of them in locations with only morning sun and other with almost full sun until 4-5 PM. This is doing even better than the others with an exceptional vigor and grow. I also experimented some twigs dieback, but just in a marginal amount, so I considered it as 'natural pruning'. I didn't have any problem with Sango Kakus. it seems that they adapted very well to warmer winters and hot climates, but hey, I jus have had them for two years, so only time will tell. Nelran
Hello emery You said: There's no treatment, all we can do is try to reduce stress. Make sure the soil is draining freely, but that it's getting enough water. Some recommend a light feed. Let me know please what kind of 'feed' you would recommend. Thanks
Hi Arthur, I use Osmocote, or a little seaweed compost on the surface. Once in awhile I'll use a 1/4 strength liquid feed if a plant seems to want it, but not every year even. -E
We've had this coral bark maple for some years and always appreciate the interest added to the garden, regardless of season. It shows red fringes if the sun shines regularly but remains mostly green during summer. Fall color is yellow as shown here but not particularly brilliant. Cold winter weather encourages red wood to show on trunk and branches. In all, a tree I consider a must-have.
Personally I just do a light fertilize in spring. I might do a liquid feed if an otherwise healthy plant seems "stuck". (No new growth). But I mostly steer clear of fertilizer, because a) the maples don't seem to care for a lot of nitrogen and b) I have too many in ground to deal with individually. Interact, that's a pretty tree, and thanks for the picture. I hope any of my 3 get that big and full some day. I will say that all 3 keep good red color in summer, but this seems not to be all so typical. Does the provenance of yours indicate it is the real SK, or is it possible a red barked seedling? No insult implied to your beautiful tree, just wondering about the summer bark color. -E
Thanks for your reply. My wild Japanese maple seems to be stuck at the moment (it's spring now in Australia). I gave it 1/4 strength fish fertilizer once a month for the last couple of months. I guess this is not enough? I'll give it a sprinkle of slow-release fertilizer and see how it goes. The lowest Nitrogen slow-release is 11 here in Australia. For some reason I can't understand, there is no high-P fertilizer here. The lowest N-P-K ratio is 9-2-6 which is the fish liquid fertilizer. I also would like to find out if Japanese maple growth is constant throughout spring/summer or is it stop & go?
I urge patience with Japanese Maples. Don't throw fertilizer at them or give them more treats beynd good soil, well drained. I like the idea of top dressing with organic soil additive each year. Replace the top 2 inches of old soil with new. Keep it fed but don't excite it with chemicals. Slow growth is likely to be better growth. My coral bark, the name means something close to sango kaku, may be a seedling variant. When we first acquired Japanese maples, we didn't understand the differences between various nursery offerings and purchased with insufficient care. Now, I will only buy a grafted tree from a reputable grower. They should grow true to form.