Needs Cables and Rods
Q: I have a powdery like substance on my maple tree which I understand is some sort of scale. Will this hurt the tree and should it
Richard from Tulsa
If the substance you see is on the bottom of twigs and looks like wet
popcorn hanging there, this is cottony maple scale.
Cottony maple scale can, if it's a heavy infestation, devastate a maple.
Often you'll find them heavily encrusted on just a few branches, but they
can spread from there, so it might be wise to treat the tree to reduce their
You can spray the tree, but this should be done by a professional. I
recommend having an oil application done in spring, then another spray in
early July. Some recent information indicates than another spray in Late
July and during September can also reduce the number of "crawlers" (baby
scales, as it were) found on the undersides of the leaves.
This would be a
worst-case scenario, having to spray this many times. You might need
multiple applications the first year, but should be able to taper back to
maybe just the oil application in spring from there on out.
However, you describe the symptom as a powdery substance. This sounds like
powdery mildew, which is often brought about by temperatures in the 60-80
degree range and high humidity.
Unless the mildew totally covers leaf
surfaces, thereby reducing the amount of sunlight the leaf gets (which
reduces photosynthesis), mildew is usually not much of a problem. If it HAS
completely covered too many of the leaves, then you might want to treat but
this needs to be done on a preventative basis.
Begin a 3-spray program in
mid-spring, spacing your treatments about 3-4 weeks apart, using a material
labelled for mildew control.
You might also be able to control mildew by pruning. By thinning the tree
out you improve air circulation and sunlight penetration, thereby allowing
the leaves to dry sooner after a rain. Removing nearby plants if the area
is too crowded will also help.
Since you are from Tulsa, I'd recommend that you contact a local arborist to check this out. You may have different scales or mildews there than here in Cleveland.
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