What’s Going on with Your Crape Myrtle?

What’s going on with my Crape Myrtle ?? What’s all the white gunk

on the trunk and branches and why are my leaves black ???

Here’s the deal - the white “bumps” on the trunk and stems are an insect

called a Crape Myrtle Scale. They moved in to NC a couple of years ago

and since we have so many Crapes in our area, unfortunately, they’ve found

a happy home !! There are several different types of scale, but these are

specific to Crape Myrtles. If you see other plants in your landscape that also

have these pesky critters, it’s a different type of scale but is treated the same.

Your Horticultural lesson for the day !

The scale attach to the stems and branches of your tree, pierce the bark and

suck juice from the layer under the bark. As they are juice sucking, they

secrete a waxy substance that covers the entire insect preventing chemicals

from reaching the actual critter! For years, the cure was to spray with

dormant or horticultural oil. This covers the insect and seals it off,

essentially suffocating the scale. The problem is that you have to insure the

entire insect is completely covered and if you only spray what you can

reach, those above your reach will continue to cause damage and eventually

spread back to the rest of the tree.

So you’re telling me it’s hopeless and I should cut down my tree ??

ABSOLUTELY NOT !!!

The most effective way to battle Scale is to use a chemical called

Imidacloprid. This is a systemic insecticide, so it is applied as a drench

treatment on the ground around the tree that is then sucked up by the root

system and travels through the entire tree so that the insects digest the

chemical as it’s feasting on your tree. Before you treat the tree, you can

mash the scale and it will squish and literally bleed. About two weeks after

applying the Imidacloprid, the scale will flake off with a gentle flick of the

fingernail!

230 East Russell Street ∙ Fayetteville, North Carolina 28301 ∙ bellsplantman@gmail.com

Phone (910) 483-8400 ∙ Fax (910) 323-4090

And what’s with the black leaves ???

The black leaves on a crape myrtle are a result of an aphid infestation (yet

another aggravating pest!) The aphids (and the scale as well) leave a sticky

substance on the leaves and the dirt and dust in the air sticks to it causing

them to appear black. The imidacloprid drench will take care of the aphids

also but the black will take a while to loosen up and fall off the leaves. You

can speed up the black removal by spraying warm soapy water on the leaves,

let it sit for 30 minutes or so and then spray the tree down with your hose to

knock it off. You won’t get it all, but that will at least make it look better!

The Bottom Line

If you’ve got a bad infestation, treat them ASAP but make sure you treat

again in mid to late March since eggs that were laid in the late summer will

come back to haunt you again. The chemical stays flowing through the tree

for about 90 days so retreat every 2-3 months to keep them from coming

back and finding a happy home in your trees !