What’s Wrong With My Crepe Myrtle? 4 Common Problems

August 22, 2013 | By | Comments (63)
Crepe myrtle

Photo: Steve Bender

Crepe myrtles are for the most part trouble-free. That’s why lazy slobs like Grumpy like them so much. But certain problems do crop up in summer that make you want to pull out the magnifying glass and burn some ants. Here are some of the most common problems and what to do about them.

Problem #1 — Sooty Mold

Black mold

Yuck! Black mold on crepe myrtle. Photo: lsuagnenter.com.

Sooty mold is a fungus that covers the leaves and looks like you just sprayed your crepe myrtle with asphalt. (Note to reader: This is seldom a good idea.) The mold doesn’t feed on the foliage. Instead, it grows on sticky honeydew secreted by sucking insects like aphids, scales, and white flies that do feed on the leaves. Get rid of the bugs and black mold will go with them.

Solution: Spray your crepe myrtle according to label directions with insecticidal soap, horticultural oil, neem oil, or Natria Multi-Insect Control. All of these are safe, natural products available at home and garden centers.

Problem #2 — Powdery Mildew

Powdery mildew

Powdery mildew. Photo: aragriculture.org

The bizarrely cool, rainy summer we’ve experienced in the Southeast this year (sorry, everybody out west) means that if your crepe myrtle is susceptible to mildew, it probably has it. Powdery mildew is a filmy, white fungus that grows on leaves and flower buds. It causes leaves to curl and shrivel. Flower buds drop without opening. Back in the day when we didn’t have resistant selections, powdery mildew was the #1 complaint people had about crepe myrtles.

Solutions: Plant a mildew-resistant crepe myrtle. Almost all of the newer ones are resistant, including those named after tribes of native Americans, such as ‘Acoma,’ ‘Arapaho,’ ‘Catawba,’ ‘Comanche,’ ‘Miami,’ ‘Natchez,’ ‘Sioux,’ ‘Tonto,’ and ‘Zuni.’ ‘Dynamite,’ ‘Early Bird,’ ‘Pink Velour,’ and ‘Red Rocket’ resist it too. If yours isn’t resistant, spray the foliage according to label directions in early summer with neem oil, horticultural oil, Natria Disease Control, Daconil, or Immunox. The first three are natural products. You’ll probably have to spray more than once.

Problem #3 — Cercospora Leaf Spot

Cercospora leaf spot

Cercospora leaf spot. Photo: Steve Bender

Cercospora is a leaf spot fungus that used to be fairly uncommon, but isn’t anymore. Grumpy has a theory that the nearly universal planting of crepe myrtles in the South has made it easy for this fungus to spread. What happens is that in mid- to late summer, angular, brown spots form on the oldest leaves. These leaves then develop fall color prematurely and drop. By fall, the tree may be completely defoliated, except for a few newer leaves at the top. Fortunately, this seems to cause no ill effects the next year.

Solutions: This fungus likes sheltered areas where breezes are blocked and the foliage stays wet for long periods. Grumpy knows this, because the one he planted in front of his house gets eaten up by leaf spot every year, while the one growing in the middle of the lawn is hardly touched. Some websites claim certain selections are resistant, such as ‘Apalachee,’ ‘Catawba,’ ‘Sioux,’ ‘Tonto,’ ‘Tuscarora,’ ‘Tuskegee,’ and ‘Yuma.’ Grumpy has his doubts, because the one that gets devoured every year is ‘Sioux.’ What to do? Plant crepe myrtles in open, sunny spots where air circulates freely. If necessary, spray with Daconil, Immunox, or Natria Disease Control when spots begin to appear.

Problem #4 — No Blooms
No matter where you live in the South, crepe myrtles should have bloomed by now. If yours hasn’t, most likely it’s due to one of three reasons.

1. Your plant is just too small to bloom. Give it time.
2. Your plant isn’t getting enough sun. It likes full sun.
3. Some crepe myrtles bloom better than others. You may have a slacker. If so, replace it with one of the selections named above.

Attention: No ants were harmed in the production of this post.

COMMENTS

  1. cooper88

    I ordered two Siren Red crape myrtles and planted them this spring. They are growing well, but they just started blooming light pink. Help!

    July 1, 2015 at 2:51 pm
  2. Steve Bender

    Fran,

    It is completely normal for the bark to start flaking off at this time of year. This is how a crepe myrtle grows — like a snake shedding its skin.

    July 1, 2015 at 1:06 pm
  3. Steve Bender

    Glenda,

    Yes, sooty mold can grow on the honeydew dripped onto branches by sucking insects. You can scrub it off using soapy water.

    July 1, 2015 at 1:05 pm
  4. Steve Bender

    Donna,

    A lot of readers have complained about the same thing. What happened is that a very cold winter severely damaged crepe myrtles or killed them to the ground. Now they’re growing back from the roots. They will not leaf out again at the top, so remove the dead trunks and branches. The shoots coming up will become the new trunks.

    July 1, 2015 at 1:03 pm
  5. Steve Bender

    Katelyn,

    This still sounds like aphids and black mold to me, so treat that as recommended.

    July 1, 2015 at 1:01 pm
  6. Fran Stone

    The bark on my 4 Crape Myrtles is peeling off? Is this normal? They all were very slow to bloom this year, but all of them finally blossomed.

    June 29, 2015 at 10:35 pm
  7. Glenda Taylor

    Can Sooty Mold get on the trunk/limbs of a Crepe Myrtle also? In late August last year the leaves turned blackish and fell off but the tree itself was (and still is a little) black. Will it die? How do I get the black mold off of the branches?

    June 28, 2015 at 10:16 pm
  8. Donna Woodford

    I planted 6 Natchez crepe myrtles in March of last year (2014) and they bloomed beautifully all summer. This spring the leaves took a long time to come out. One is blooming and the others have a few blooms but I had to prune a lot of dead branches out of them including main trunk stems. We had a late freeze (northwest Alabama) but I am not sure if they were budding then. Could that be the problem?

    June 27, 2015 at 2:43 pm
  9. Katelyn

    Mine have almost sticky black on the leaves and crystals (looks like salt) on the bottom of the leaves, not as black as the mold picture, and no blooms yet. They are larger trees but just planted this year (early early spring). What could be the problem?

    June 25, 2015 at 7:27 pm
  10. Steve Bender

    Vicki,

    Are there webs covering the ends of the branches? This sounds like the work of fall webworms. Try spraying those branches according to label directions with neem oil.

    June 25, 2015 at 1:27 pm
  11. Steve Bender

    Adina,

    My guess is the water from the sprinkler system isn’t reaching this tree any more. Maybe one of the sprinkler heads has stopped working. I’d also check to see if there is any damage to the trunks near the base.

    June 25, 2015 at 1:25 pm
  12. Vicki Endress

    My crape mytles bottom branches are covered with spider like webes. Is this healthy or not .It is 35 feet tall, so it is a bite to tall to spray the whole tree . What do I do ?

    June 23, 2015 at 7:04 pm
  13. adinahoshour

    Can anyone advise why my Natchez crape myrtle is displaying severe leaf wilt? I have two in the front yard with full sun exposure, but only one appears to be struggling and it has been in the ground for 5 years. Is it possible that it is receiving too much water from the sprinkler system or not enough water? The leaves are green, but wilted. The Japanese beetles are feasting away despite my having paid a lawn service to spray the tree. The temperature has been around 100 degrees…but none of my other trees are displaying this severe wilt.

    June 23, 2015 at 5:57 pm

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