At 01:05 PM 4/16/03 -0400, Jim S wrote:
Anyone know what would cause initially healthy new growth on a maple to
suddenly start to wilt?

I don't think I overwatered. The soil is well-draining. It's actually
happened to 2 out of 4 maples I have. Could it be fungal?

Jim

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.

Dig around the root crown a bit and look for blackened roots and bark
(sometimes in patches or stripes), a sure sign. There is little you can do
other than to keep them on the dry side with good light, no nitrogen.
Repotting will sometimes work if they are in dense soil, but that doesn't
sound like the case here.

The water molds are a group of root fungal pathogens with similar symptoms.
They are systemic diseases that attack the vascular system so water cannot
proceed up the stem. That is why the leaves wilt. The initial reaction is
to give them more water and this of course exacerbates the problem. It is
very often fatal, but sometimes only part of the tree will be affected and
it will fight off the attack. Since the diesease is systemic, all the over
the counter fungicides are nearly useless.

I can't remember them all, but I believe the water molds include Pythium,
Phytophora, and Fusarium. Another nasty that behaves like this is
Verticillium, but I can't remember if it is referred to as a water mold.

It would be nice for Nina to help us here.


Brent in Northern California
Evergreen Gardenworks USDA Zone 8 Sunset Zone 14

http://www.EvergreenGardenworks.com

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