On Mon, 03 May 2004 13:56:57 GMT, "Chris" wrote:

My front crepe myrtle has a very bad case of powdery mildew. It had it last
year, too, and never flowered. How do I stop this cycle? Someone posted
something about using a milk solution. Does this work? I bought some
really nasty stuff last year that required me to wear protective clothing
and a ventilator when I applied it. Supposedly it killed everything. It
didn't appear to work and, given that almost everything else I use is
environmentally-reasonable, I'd rather not use that again.



Any suggestions?
Thanks.
Chris


Well, I disagree with almost everything Roy has said about pruning
crapes. I never prune mine ( full grown when I moved in 10 years ago,
probably 40 years old or more total) except to remove root sprouts,
the occasional dead branch, and low limbs that hit the house or poke
my eye. They are close to 25' tall (i.e., they ain't getting much
taller) and they always bloom well.

Topping is a brutal practice--not "murder" perhaps, but it will
drastically shorten the life of the plant. When you remove all the
plant's energy reserves every year, you deplete stored starches and
sugars to the point they can no longer afford to make flowers--they're
just struggling to survive. Thin out the cluster of sprouts that grow
this year, but leave 2 or 3 strong whips on each stub, and let them
develop into branches over time. Don't top anymore and leave the poor
things alone and they'll recover eventually. Yes, I know some people
top annually and still get lots of blooms. The great irony is that
these amazingly tough plants manage to survive the worst we dish out
and then we use it as an excuse to continue bad practices.

Now, if you want to cut down to the ground periodically and create a
big bushy cluster of sprouts, more power to you, but IMO the best
thing about crapes is the intricate branch structure and the smooth
trunks with flaking bark. The whips that come off the ground take
years to reach a point where you can enjoy these features.

As for fertilizer, most Austin soil has too much P and K already, and
our creeks are suffering from the runoff of excessive fertilizer
applied by overzealous homeowners. The bigger problem is our high pH
(we're sitting on a big chunk of limestone, basically). Iron.
magnesium, calcium, etc. can bind with each other/other soil
components, making these micronutrients unavailable to the plant. A
sprinkling of epsom salt can add a bit of Mg to the soil and improve
blooming. Still, I would not recommend any fertilizer unless/until
you get a quality soil test that shows some deficiency, and then only
with a fertilizer designed to address only that deficiency. Don't use
the A&M soil tests--they use HCl to test in an assembly-line method,
and the results are skewed because of that (in effect, the acid
negates the problems caused by the high pH and your test will show
elements that are in the soil but not available to the plants).

Good luck,

Keith Babberney
ISA Certified Arborist
For more info about the International Society of Arboriculture, please visit http://www.isa-arbor.com/home.asp.
For consumer info about tree care, visit http://www.treesaregood.com/