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Crape Myrtle Problem

Gardening Reference » Gardening in 2006
by davidk07 on July 03, 2006 01:49 AM
Does any one know what the black film/soot substance thats covering my crape myrtles is? Its covering the leaves and branches, and will flake off with a fingernail. Does anyone know what it is and how do I get rid of it? It seems to be doing more harm than good. Thanks.

David

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"Consider the lilies how they grow: they toil not, they spin not; and yet I say unto you, that Solomon in all his glory was not arrayed like one of these." KJV Luke 12:27
by luis_pr on July 03, 2006 06:22 AM
Hello, David. You are probably suffering from an aphid infestation. An example (photos) of such can be seen in the middle of this webpage: http://insects.tamu.edu/extension/bulletins/b-6047.html

Aphids feed by inserting their mouthparts into tender new leaves from which they suck sugary plant sap. As they feed, the aphids excrete large amounts of a sugary liquid called honeydew. With a large aphid population, the honeydew can completely coat leaves, which serves as food for the sooty mold fungi, as well as various other insects like ants, wasps and flies, etc. Sooty mold is harmless so you should concentrate on controlling the aphid infestation instead.

In addition to switching to crape myrtles that have resistance to aphids, you can always wash them away with a strong jet of water or use natural predators like ladybugs, lacewings, hover fly maggots, parasitic wasps and entomophagous (insect feeding) fungi. Some of these are probably available now in your local organic minded nurseries.

If you want to use insecticides, be aware that these will also kill the natural predators listed above. You can try insecticidal soap (e.g., Safer Insecticidal Soap), horticultural oil (Sunspray Ultra-fine Spreay Oil), pyrethrins (Schultz Rose & Flower Insect Spray), neem oil (Bonide Bon-Neem, Green Light Neem Concentrate, etc) or products containing permethrin, cyfluthrin or malathion. Read the labels and take appropriate safety precautions. Also, consider rotating insecticides in order not to end with pests that resist any one insecticide. That way, if they do become resistant, when you rotate, the other insecticide will kill them.

I hope that helps. Good luck,
Luis
by davidk07 on July 03, 2006 07:13 AM
Thank you very much Luis, I wil give those things a try. I planted 2 at the same time in my front yard and 1 thrives and the other isn't. Both are in full sun and the 1 that isn't thriving is covered in this black soot, therefore I assumed the black soot was hindering it. I have triaziside spray and ultrafine that I just got for a daylily problem. Should I try the ultrafine first?

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http://www.firstgiving.com/runningforDaniel

"Consider the lilies how they grow: they toil not, they spin not; and yet I say unto you, that Solomon in all his glory was not arrayed like one of these." KJV Luke 12:27
by TulsaRose on July 03, 2006 07:36 AM
David, did you check out the information I gave you in the forum at NHGC this morning?

Quote:

Hi David...sounds like your Crape Myrtle has Sooty Mold. There is a description and care instructions at this website for Clemson University...
http://hgic.clemson.edu/factsheets/HGIC2002.htm

Scroll down to the topic of Sooty Mold.

Unquote!

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Rosie z7a
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by davidk07 on July 03, 2006 08:53 AM
No, but I have now, thanks Rosie!

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http://www.firstgiving.com/runningforDaniel

"Consider the lilies how they grow: they toil not, they spin not; and yet I say unto you, that Solomon in all his glory was not arrayed like one of these." KJV Luke 12:27
by TulsaRose on July 03, 2006 11:30 AM
I ran across that website while searching for Powdery Mildew solutions for my Crepe Myrtle. Bookmarked it for futur reference. [Smile]

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Rosie z7a
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by davidk07 on July 03, 2006 02:33 PM
I went out today, looking for the aphids I didn't think had any thing to do with it, and found out upon close examination that I was wrong and they were covered with them. Thanks for your help, maybe now I can respond and clear em up!

David

* * * *
http://www.firstgiving.com/runningforDaniel

"Consider the lilies how they grow: they toil not, they spin not; and yet I say unto you, that Solomon in all his glory was not arrayed like one of these." KJV Luke 12:27

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