A Hortline (UBC Botanical Garden's gardening question telephone answer line) customer reports that his otherwise healthy and normal looking 30 year-old Acer palmatum trees have started holding onto their leaves over the winter. It's not until the spring, when the buds start to expand, that the old leaves abscise. I know I've seen this behaviour, but as far as I can remember, only on juvenile plants in containers--never on plants in the ground. I expect it has something to do with moisture being withheld when the leaves would normally be senescing, but I'm not a plant physiologist. Has anyone out there seen this phenomenon, and more importantly, does anyone have an explanation for it? I'd love to hear from grafters and growers about this...
Hi Douglas: Is there any way you can ask the person where the Maples are being grown? I am interested in how cold it has been at that location during the Winters. How long has this condition been going on? We've seen it occur in the nursery with some Atropurpureum forms both palmates and dissectums but we attributed it to lack of cold weather for us. We've seen this condition much more frequently with certain Acer Japonicums. I can equate things to how Pin Oak planted in the ground works for us in that without any real cold the leaves stay on the trees until the new leaf buds start to initiate growth in the Spring. If we endured any prolonged cold the leaves will drop off real easy but we have not had any real length of cold here for almost 5 years. If cold or lack thereof is not the problem then we need to know what caused the trees to prematurely harden off and then stop before the hardening off process was concluded. A severe cold with a lack of water and nutrient flow during the start of senescence could cause the plant not to carry out its normal abscission functions and then abruptly shut down for the Winter. Was the newest growth in the Spring adequate or relatively normal to previous years? Just some quick thoughts. Jim
Not to be confused with fungus problems, this is common up here, too, so it's not just a hot climate phenomenon - whatever it is (I've also heard theories, don't have definitive answer). You'd love to hear from grafters? Hmm, sounds suspicious...
Hi Ron: You are not that much cooler than us here. The cold becomes an issue as to when it gets cold and for how long as we can have Decembers with 90° in the first week and 10° around Christmas. It is rare but it can happen to us here and has. The Maples that did this for us were in the ground. I've only seen it happen twice with Don's Maples. What plants in Washington are not dropping all of their leaves? Essentially what I am wondering is whether this happened one time, was this an isolated event or has it been habitual. Then, how well did the trees respond in the Spring. We do not know enough of the background info yet to start bantering around any solid ideas at this point. Jim
Various Japanese and related maples retain many leaves, perhaps periodically. I've never made notes, but there has seemed to be quite a bit of it lately, enough to generate comment. It's as described here, with them all falling off eventually, in the manner of a beech or a pin oak.
Concerned Maple Owner We have a 25 year old japanese maple in our front yard in Oakland, CA. In our mild climate, the leaves usually turn yellow/reddish in November and fall. This year the leaves turned brown, curled, and remain on the tree. Only unusual condition this year has been the late fall weather. Heavier than average early rains (in Oct/Nov) followed by a sunny December. Recent heavy rains have not removed the leaves.
Our changing weather patterns are causing very many unusual (or just different) patterns within ALL of our garden plants Methinks the poor trees simply don't know what to do next :)
Even here in Westchester County north of NYC, my Koto no ito has held onto quite a few leaves this year. The autumn transformation happened in stages this year with all the trees, and my maples came in about three different groups the Koto no ito was in the last. We had an early cold spell and then a fairly mild, wet autumn.
