HELP,

I have had several (25 or so) larch (collected in northern MN) for
the last 7 years. Over that time I have lost 3 or 4 of them. This
year they are dieing 1 by 1 for the last 2 weeks. It takes 3 or 4
days to go from nice and green to totally dead. From what I have
learend , they have the "mysterious wilting disease". Does anyone
have any other ideas on what they may have, or any idea as what I can
do to stop the bleeding ?

thanks in advance

Bob Seele in northern Illinois

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If it's really a "wilt", here are 3 possibilities

1) Armillaria root rot. Look in the pot for black "shoelaces" among
the roots, or notice golden mushrooms growing in the pot.

2) Verticillium wilt. Take a tree you know is a goner, and whittle off
the bark until you hit the first few rings of wood: do you see brown
streaks?

3) Pine wilt, caused by a nematode. You'd need to take a sick tree to
the nearest Cooperative Extension office to diagnose this.

However, I find it hard to believe that all your tree could catch a
root disease, unless you submerge your pots to water them and share the
"bathwater" among the trees. Root diseases aren't very contagious as a
rule. Take a good close look at the yellowed branches for signs of
larch casebeares or larch beetles (do a google image search to find
pictures of symptoms).

Robert Seele wrote:
HELP,

I have had several (25 or so) larch (collected in northern MN) for the
last 7 years. Over that time I have lost 3 or 4 of them. This year they
are dieing 1 by 1 for the last 2 weeks. It takes 3 or 4 days to go
from nice and green to totally dead. From what I have learend , they
have the "mysterious wilting disease". Does anyone have any other ideas
on what they may have, or any idea as what I can do to stop the bleeding ?


Next time you have a body, do an autopsy. Cut the trunk
straight across about midway up. See if the wood is dark or
"normal" colored. If dark you have a fungal problem that
closes up the xylem, killing the tree. Larch are
susceptible to Phytophthora fungus, among others.

I know of no cure, and even Ortho's "Garden Problem Solver"
holds out little hope.

Jim Lewis - - Tallahassee, FL - Nature
encourages no looseness, pardons no errors. Ralph Waldo Emerson

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John Biel said:

Years ago the folks at our horticultural college at Guelph, Ontario,
were contactedn about this. They believed that it was some sort of fungal infection but had not heard of these symptoms before as occurring in larches. An analysis was not done. They also suspected it is probably unique only to container grown larches.

Guelph has a fine University, but that is *not* helpful. If something
is "unique" to containerized larches, it would most likely be
physiological, not fungal. It's unseasonably hot right now- heat
stress? If it's fungal, it has almost certainly been reported before
on larch, and someone has to examine a specimen to find out.

If Robert wants to send me a [very] recent corpse, I'll look at it.

Nina. CSI mushrooms indeed!

Nina wrote:
If it's fungal, it has almost certainly been reported before
on larch, and someone has to examine a specimen to find out.

Ortho's Home Gardener's Problem Solver (since larch don't
grow down here, I have to look these things up) says they
are VERY susceptible to Phytophthora cinnamoni and P.
lateralis, and since the graying foliage seems to be
associated with Phytophthora on other plants . . . . ?



If Robert wants to send me a [very] recent corpse, I'll look at it.

Take her UP on it!



Nina. CSI mushrooms indeed!

:-)

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