Japanese maples ailing

9 years ago

Hi - my two Japanese maple are 'ailing' this year. I live in Ottawa (4b ) with sheltered backyard and south western exposure. When we returned from an extended holiday recently I found their leaves quite badly damaged.
Most reading I've done suggests that problems occur from our hot summers but these maples have been happy over recent years. At first I thought the problem was due to loss of some shade from a hard prune of a large shade maple on the south side of the yard. However, one of the J maples is in fairly deep shade so this does not seem reasonable.
A closer look at the leaves (is there a way to add photos?) reveals series of tiny pinprick-like holes that suggest an insect infestation, but I see no sign of insects.
I would appreciate any advice as I love the colour oand texture that these trees add to our yard.
Thanks
L. Murphy, Ottawa

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Comments (5)

gardengal48 (PNW Z8/9)
9 years ago
That is leaf scorch and it is due to uneven watering.......periods of adequate rainfall or irrigation contrasted with periods when the soil became too dry. Lots of sun and high temperatures can exacerbate the situation.

Were the tree watered during your extended holiday? The soil surrounding the roots should stay consistently moist - never too wet but never allowed to dry completely.

While the trees are not attractive with that dry, browned foliage, they are not in any danger. No insect issues.....the spotting in the interior of the leaves will dry and fall out, leaving tiny holes. Just keep the root zone properly moist and they will recover. A layer of mulch surrounding them will help to avoid moisture evaporation from the soil.
cdnmartha
Original Author
9 years ago
Thanks very much for this information. Ottawa had over 250 mm of rain in July so perhaps this is the problem. It has always had a layer of mulch in place. Thanks again.
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Smivies (Ontario - 5b)
9 years ago
Maple Anthracnose has been a problem in eastern Ontario this year thanks to the moist weather (especially in May & June). The tree will be fine and, if we have a 'normal' spring next year, the anthracnose will probably not recur. It is an infrequent fungal leaf blight of maples in this area, only occurring during unusually wet springs.
gardengal48 (PNW Z8/9)
9 years ago
Sorry but that is NOT anthracnose!! In fact, it is not pathogenic at all. It is cultural in nature only and not a huge concern. I have grown and sold hundreds of JM's in my day and the appearance of this one is consistent with a summer season water issue - too much followed by too little combined with high temperatures or a lot of sunlight.

AFA wet springs go, the PNW consistently has mild wet springs and is host to a lot of fungal issues at that time of year. And JM's can certainly get them but none that look like this. And any foliar evidence of spring fungal issue would be long gone by now......the trees will drop the affected leaves and releaf.
Smivies (Ontario - 5b)
9 years ago
Hmmm...fair enough. I wonder though about the pre-requisite conditions? There hasn't been a period of dryness in Ottawa this summer and the high temperatures have been well below a typical summer (high is low 80s vs. high 80s, low 90s). Almost all the Silver and Sugar Maples were affected this spring and shed their badly blighted leaves but retained the partially blighted ones.