With all your experience with maples what is your opinion about what Acer Palmatum cultivars are more resistant to Powedery Mildew? Are all Acer palmatums susceptible to this fungus when exposed to his ideal growth environment (Shady conditions high humidity...)? Regards.
Mildews in general are promoted by summer conditions of dry soils combined with damp nights. Here we see heavy mildewing of some big-leaf and Norway maples, at this time of the year. Not so visible on Japanese maples. In Portugal you will also have an annual summer drought.
Thank Yo Ron and Gomero, i appreciate. By the way: putting mildew a side, what is everyone`s opinion about the the most hardy Maples in terms of general adverse growing conditions (cold, heat, drought,wind)? Problably the oldest cultivars? I tried to search for this information but i didnt find much. regards.
Francis, 'Seyriu' seems to a pretty tough cultivar. It grows well in Houston, Rome and Toulouse which are 3 examples of less-than-ideal conditions for Japanese Maples. Gomero
For what it's worth, and I've only been growing maples for one summer - but it was a doozy, with more than 50 days of 100F or hotter between May and September, and most nights not getting below 80-85F - but a few cultivars that really impressed me this summer with the lack of 'crispy leaves' were my 1yr grafted Wilson's Pink Dwarf, 3yr Murasaki hime (not M. kiyohime, just hime), 3yr Olsen's Frosted Strawberry, and 2yr Shin hikasa. The first two only started developing crispy leaves well into August, and the last two barely got singed on the leaf edges. Both Wilson and Olsen were shipped to me and potted up mid-summer (generally a no-no, especially in that kind of heat), Murasaki hime I had purchased and potted last fall, and Shin hikasa was shipped to me in its pot in early August. Obviously, I can't say what their cold tolerance will be since this is the first winter for all but the Murasaki hime, though that one did well under protection outside in an unusually cold winter for us...
