Q: Is this anthracnose on my 5′ tall Japanese maple? It’s in a 24″ wide, foam pot.
A: I was puzzled by the pattern of damage, so I sent this to my friend Norm Mittleider at Art-of-Pruning.com. He replied:
This is a real head scratcher. Based on the photo, I would rule out several probable causes for the leaf spots. It is definitely not a result of insect damage. It is also not caused by a disease, which rules out anthracnose, a fungal disease that produces multiple circular patterns across the leaf surface. Could it be mechanical damage? There is a very remote chance that it may be leaf blower damage.
The homeowner replied:
As you suggested, this could have been from my leaf blower, as the tree top sits close to the level of my deck.
Another intriguing mystery solved!