Crape Myrtles yellowing in FL - in August?

I have several crape myrlte trees which were planted in late March.
They have been doing great, putting on much growth for young plants and blooming with colors as expected all summer.
Now, in mid-August, several have some yellow leaves. One has quite a few and almost no colored blooms left.
What is likely to cause these yellowing leaves? I did a search and found no mention of yellow leaves on crape myrtles aside from the change of color in the fall.
There have been a number of ants running up and down the branches. When I checked the trees after seeing the yellow leaves, there seem to be more than usual. I'm not sure if this is the cause. I also don't know what kind of ants they might be; they seem somewhat small for fire ants.
I've ensured the trees have a lot of water several times a week. There still is time-release fertilizer on the ground from my last application a couple months ago. The soil is mostly sandy and I live in Orlando, FL. The trees get full sun much of the day. It's been in the lower-mid 90s and high humidity for at least 2 months.
Do I need even MORE water? Do I need some added fertlizer? If so, what kind? Do I need to cut back on the water? Do I need to kill the ants? If so, how?
Any information on yellowing of crape myrtles in August in FL would be useful.
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Apropos wrote:

If the leaves are dry and yellow the tree may not have enough water given the sandy soil. If they are supple and yellow maybe too much water. I wouldn't have fertilized them until they were well established if ever.
--

Travis in Shoreline (just North of Seattle) Washington
USDA Zone 8
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Thanks. Hard to tell if they're supple or not. Not REALLY dry... but they're yellowing, dying and then falling off (but others are green and healthy). So it's not like they're yellow and just staying up there. They're not as dry as the leaves I was used to in the fall in the north, though - those were DRY.
As for fertilizer... even the dirt when I transplanted had some of the osmocote on top of it. It's time release and I didn't put much. Anyway - they survived 4 months with that same fertilizer without problem. It's not like I JUST put something on then they started turning....

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Over watering is the problem, most likely.
However, I have a question for you. Why do people like you ask a question then search through the answers and pick the one you like best? Why is that? You ask a question, get an answer, then argue the answer.
On Tue, 16 Aug 2005 13:46:41 -0400, "Apropos"

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On Mon, 15 Aug 2005 21:14:38 -0400, "Apropos"

As usual a simple google search of " crape myrtle yellow florida" will garner lots of solid information.....
http://edis.ifas.ufl.edu/pdffiles/MG/MG26600.pdf
Google is your friend .....:>)
http://www.ncan.com/nursery%20notes%20articles%202003/Yellow%20AlertNN.pdf
Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel. -- Aldo Leopold
Acts of creation are ordinarily reserved for gods and poets. To plant a pine, one need only own a shovel. -- Aldo Leopold
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Thanks. I tried the google search. However... google was a little TOO much a friend when I tried :) I found many, many results but nothing which talked about yellow leaves in the summer without a mold or mildew problem (which I checked out but found I didn't have)
wrote:

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