In september 13 i found a twig with leaves withering. I observe also 3 slots on branches scaring queekly. Do you confirm a first year Verticillium ? I join a picture of the roots as they look to day. (Iroha-momiji=palmatum thunbergii , growing in pot without graft. Thanks
Maybe others will give their opinion too... I don't think its verticillium. It usually does not close up like what's shown in pictures 2 and 3. Since the wound wood has closed up the open areas, this tells me your tree was healthy enough to overcome the previous damage. The roots and bark look healthy, with the exception of the area in photo 1. What caused the leaf failure? I suspect that the leaves that are out beyond the damaged area on that branch (in 2 and 3) suffered cell damage due moisture loss. This would be caused by transpiration (water loss in leaves from sun, heat, and wind) and the loss of moisture from the damaged area, and the trees inability to supply enough moisture, because the damage was blocking (or disrupting)over half of the vascular system along that branch. Now that the damage has closed, the tree should do a better job keeping up with moisture loss along that branch. My advice would be to remove twig in photo 1. Monitor the tree to make sure it continues to recover. Keep it healthy and try to minimize stress (including drought stress). If necessary, use a organic fertilizer (low nitrogen, balanced, remember that less is best) after new spring growth hardens off (Late Spring and early Summer is the time when Japanese maples are most effective at "healing" wounds). If the branch in photos 2 and 3 shows slight signs of struggle, consider moving the tree into a less harsh growing spot (or do it anyway, to be safe) and avoid hot afternoon sun, preferably protected from drying winds. If the tree continues to grow and recover, the once wounded and now closed area will become less noticeable and less of a liability. But if this branch continues to be a problem, then you should consider removing the branch at some point. If removing the branch is devastating to the trees appearance and structure, then I would definitely get the tree into a protected micro climate in your garden to do everything possible to help minimize stress and give the tree a best chance of full recovery.
I agree with JT, the pictures 2 and 3 show old wounds that are healed with "wound wood"; the original damage most likely occurred a long time before September 2013 for them to have healed that much. One possibility is infection from pseudomonas syringae bacteria during cool wet weather in early 2013. The bacteria may have entered through physical damage to the bark and caused the damage to grow into a lesion. When the weather became warmer and dryer the infection could no longer thrive and the tree managed to heal the wounds through the growing season, giving us the picture we see now. Pseudomonas syringae infection can be spotted usually in late winter and early spring. Symptoms are tip and twig dieback and bark lesions; affected bark and twigs look black or purple/black when the infection is fresh.
These healed cuts look like mechanical damage to me, perhaps caused by an insect of some sort. The ragged bits of bark don't look so much like pseudomonas to me, maybe more like slug or snails, but of course it is hard to tell after the fact. Fully agree with Maf and John, doesn't look at all like verticillium. Time to repot, too! ;) -E
Thanks for your detailed responses , i apreciate your understanding. JT, i agree your explanation. maf, no Pseudonomas, i know it's process in my orchard. No Verticillium too (i never had), so imagine how i feel more relax ! emery, slogs or snails , could bee !!! This year , I had a lot of big long grey slugs . In spring , my old friend helgehog was dead , i must do his job ... Time to repot , i agree . This 4 years Iroha-momiji (seeds from Kyoto) : photo number 34 in my collection. http://jalbum.net/a/1438483
Very beautiful photos! Thanks for sharing such beauty on this cold Winter day. I love your beautiful maples and your beautiful garden! I like your seiryu in 17/45 I like how you train your arakawa in 24/45, pulling some of the branches horizontal to give it more character and the look of age. I love the myriads of colors and textures in the last few photos, especially 45/45.
Thanks for your visit and yours very nices appreciations. I applaud your well dressed garden, what a care ! Perfectly appropriate to your house ; my Dear, quite différents approches !
