Brent said:

If you have Japanese maples, Acer palmatum, it is very likely they have a
root fungal disease, one of the dreaded water molds. A. palmatum is very
susceptible to these diseases and they are worst are this time of the year,
striking just after the new growth appears.


The water molds are a group of root fungal pathogens with similar symptoms.
They are systemic diseases

No, actually, water molds aren't systemic. But because they kill
roots, they doom the rest of the plant.

Since the diesease is systemic, all the over
the counter fungicides are nearly useless.

Over-the-counter fungicides may work *preventively*, but once the
tree has root rot, it's on its own to fight it off.


I can't remember them all, but I believe the water molds include Pythium,
Phytophora, and Fusarium.

Pythium and Phytophthora are water molds, Fusarium is a true fungus
that causes damping-off or systemic infection. Mycologists have
always known that water molds weren't really fungi, but now it's
official: they're algae. The NYTs now refers to them as
"fungus-like" organisms.

Another nasty that behaves like this is
Verticillium, but I can't remember if it is referred to as a water mold.

This is another true fungus that causes systemic infections, and is a
scourge of maples.

Anyway, I agree with all the advice Brent gave on treatment: don't
overwater, repot if the soil is dense, watch and wait.



--
Nina Shishkoff

Frederick, MD

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