Japanese Maple - Changes in Leaves - Ask Extension
Many of the leaves on my ornamental Japanese Maple (I think) are turning brown. Never happened broke. Coukd ut be heat damage or something help. Damag...
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Japanese Maple - Changes in Leaves #917392
Asked September 13, 2025, 11:45 AM EDT
Many of the leaves on my ornamental Japanese Maple (I think) are turning brown. Never happened broke. Coukd ut be heat damage or something help. Damage seems to be. more on top of the tree, lower leaves less affected.
Thanks for your help.
Howard County Maryland
Expert Response
Since the past 6 weeks or so have been abnormally dry, drought stress is certainly possible (unless you've been watering periodically), and may be one factor behind any early leaf death/shedding. Otherwise, the main symptoms we're seeing in the photos is powdery mildew, a very common fungal disease across many plants for this time of year. There may be an overlap with a bit of different type of fungal leaf spot as well, which is similarly common by the end of the growing season.
Neither is a serious threat to long-term plant health and does not need to be managed with fungicides. (Fungicide applications can't cure existing infections anyway; they only help protect healthy growth.) Since the maple is about to shed leaves for autumn in the coming weeks, the management of leaf diseases is not necessary, though you can rake-up its leaves later (once they've fallen) and dispose of them, if you want to remove some of those overwintering fungal spores.
If you haven't been irrigating lately, monitor the tree for watering needs so its roots are less stressed. This also helps the buds it's developed for next year's growth (which will lie dormant on the branches all winter) from dehydrating too much, which could kill them in dry conditions continue into late autumn or winter. Feel the soil in the root zone about 6 inches deep: if it's becoming somewhat dry to the touch at that depth, water thoroughly; if it's damp when checked, watering can probably wait. The linked page provides more tips for watering.
Miri
Neither is a serious threat to long-term plant health and does not need to be managed with fungicides. (Fungicide applications can't cure existing infections anyway; they only help protect healthy growth.) Since the maple is about to shed leaves for autumn in the coming weeks, the management of leaf diseases is not necessary, though you can rake-up its leaves later (once they've fallen) and dispose of them, if you want to remove some of those overwintering fungal spores.
If you haven't been irrigating lately, monitor the tree for watering needs so its roots are less stressed. This also helps the buds it's developed for next year's growth (which will lie dormant on the branches all winter) from dehydrating too much, which could kill them in dry conditions continue into late autumn or winter. Feel the soil in the root zone about 6 inches deep: if it's becoming somewhat dry to the touch at that depth, water thoroughly; if it's damp when checked, watering can probably wait. The linked page provides more tips for watering.
Miri
