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

August 22, 2013 | By | Comments (24)
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. Audra Swink

    We planted 7 crepe myrtles four years ago, we have a lot of limestone in our soil. We planted Miami, Tuscarora, Catawba and Pink Velour, my problem is they bloom just great however each one is only still about 24-30 inches tall. Not much bigger than when we bought them. We dug down about 18 inches and cleared as much limestone as we could then refilled with organic compost. Is the limestone inhibiting their growth? Should we move them? Thanks!

    August 22, 2013 at 10:43 am
  2. Irene Adams

    I live in the Seattle area and was told that crepe myrtle would do fine around here. The plants look great and are trying to bloom, but they look just like they did 6 weeks ago. They just won’t open. The weather here has been sunny and warm. Could it be that the plants are just too young?

    August 22, 2013 at 11:32 am
  3. Diane Flood

    I planted 6 4ft tall crepe myrtles that were in full bloom, 5 years ago. As of today they shrunk to 3ft tall, and are now getting blooms again. Why so slow to grow? Full sun and no problems to the leaves that I can see. Any suggestions? More water? Fertilizer more? HELP!!!

    August 22, 2013 at 12:58 pm
  4. Judy west

    I have a Razzle Dazzle crepe myrtle-the branches are just black. How do I get rid of this mess? It bloomed really pretty last year but not this year.

    August 22, 2013 at 3:39 pm
  5. Diane

    Powdery mildew can also be effectively controlled on plants by spraying a dilute skim/non-fat milk solution daily. (1 part milk to 9 parts water) I use powdered dry non-fat milk & dilute it to the same strength. It’s a very good organic option & because it is non-fat, it doesn’t smell. Spray daily for one week, then maintainence of once or twice a week. It also adds a subtle sheen to the leaves from the milk protein, which is thought to have something to do with why it’s effective.

    August 22, 2013 at 7:39 pm
  6. Monica

    Any recommendations as to the type(s) of crepe myrtle to plant in the northeast (PA to be exact). Thanks.

    August 22, 2013 at 9:14 pm
  7. Arthur in the Garden!

    I think the bigest problem is bad prunning. Don’t lop them off!

    August 23, 2013 at 11:54 am
  8. MBee

    Don’t click on Land Tope’s comment; it’s a virus.

    August 24, 2013 at 2:52 pm
  9. Mbee

    Arthur in the Garden: if you don’t lop them off, do you trim them at all? How do you get them to look like mini trees like in the photo above?

    August 24, 2013 at 2:53 pm
  10. Marilee

    We have several crepe myrtles in our yard. Each year they come out with very small sparse leaves except at the new growth where the leaves appear normal size. They do flower each year. However they are not near as spectacular as all the other crepe myrtles in the area, because their leaves are so sparse. Is there anything we can do to help them? I do have a picture, I cannot figure out how to post it here.

    August 24, 2013 at 3:56 pm
  11. roberta4949

    those strongly pink crapes are gorgeous, I am totally jealous, well not to much jealous, lol.

    August 26, 2013 at 12:38 pm
  12. Susan

    Hi there, I asked you a question about my sarah’s favorite crepe myrtle in April 13. We planted it last year and this year only some of the branches leave out and bloom a little. 1 out of the 3 branches is not leafing out at all. when I snap the branches of the one that is not leafing out, it’s green inside. The plant is about 6 ft tall when we bought it. We live in Virginia. Do you think that this plant is half-dead? or do you think it will come back full life next year? one mistake that we did when we planted it was overwatered (we watered and then it rained a lot!). the soil is clay. Thank you for your comment.

    August 27, 2013 at 2:22 pm
  13. Jan B.

    We have a beautiful HUGE crepe myrtle that didn’t bloom it’s dark red flowers this year. I think it may be the spot fungus you mentioned cause it is looking like fall(dropping colored leaves) even though it is late august. Do you suppose a stag horn fern that has taken up residence all around the trunk (it’s huge too) could be harming the tree? I’m guessing this tree is about 30 years old. Or could it just be old age? We live in central Florida and have had a very wet summer. I can send a picture via email if it would help the diagnosis! Thanks!!

    August 28, 2013 at 8:54 am
  14. Steve Bender

    Audra,
    I would suspect compacted soil is the problem. It is more important how wide the soil is loosened at planting than how deep. What you might want to do is replant your trees this fall after the leaves drop. Dig a hole for each that is three times wider than the root ball, but no deeper. Fill in around the root ball with the excavated soil — no amendments needed.

    August 28, 2013 at 10:42 am
  15. Steve Bender

    Irene,
    Crepe myrtles love sun and heat. If your weather has been cool and cloudy, that’s probably the cause.

    August 28, 2013 at 10:43 am
  16. Steve Bender

    Diane,
    Can’t say why your plants died back. Maybe it was a severe drought a couple of years ago. I wouldn’t fertilize them now. Do this next spring.

    August 28, 2013 at 10:48 am
  17. Steve Bender

    Judy,
    Your crepe myrtle has sooty mold. See the photo above.

    August 28, 2013 at 10:48 am
  18. Steve Bender

    Monica,
    I suspect that you live a little too far north for them, but one you might want to try is ‘Red Rocket.’

    August 28, 2013 at 10:49 am
  19. Steve Bender

    Susan,
    I think you’ll have to wait to next spring to see which branches make it. Prune off any that don’t leaf out again.

    August 28, 2013 at 10:53 am
  20. Steve Bender

    Jan,
    I think it’s the weather, not the fern.

    August 28, 2013 at 10:53 am
  21. Why Tree Leaves Fall Before It’s Fall – The Daily South | Your Hub for Southern Culture

    […] pest attacks can cause leaves to turn color prematurely and drop. For crepe myrtle, the culprit is Cercospora leaf spot. For river birch (Betula nigra), the villains are aphids. Large trees are too big for homeowners to […]

    August 29, 2013 at 10:01 am
  22. Camille

    I know you won’t like this but the crepe myrtles (large variety) planted as a property line border were out of control, so I murdered them. They had been pruned a few years ago, so there were lots of extremely long spindly limbs that made a mess of our cars, since they are planted right up against our driveway. I got sick of the mess on our cars and also not being able to see when we backed out into the road (the limbs stretched out about a foot beyond the curb). So they’ve been murdered and at the first of September no less! They are not altogether my plants since they are on the property line and the neighbor planted them years before we moved here. So, I will be murdering them every year. Some of us have to do what makes sense and do not have the luxury to follow your obnoxious advice.

    September 2, 2013 at 5:20 pm
  23. Dea

    Living in the Houston area, we see crepes at all stages — from bushy shrubs to tall, trunk-braided trees — and have all the same problems as above (except those of the colder climates. Crepe myrtle is known as the “lilac of the South,” and we were told by our arborist that generally speaking crepes will do well where lilacs don’t get cold enough, and vice versa. So as a rule of thumb, wherever we have lived, I have always checked to see if lilacs will grow in an area, and if they will, planted them; if not, crepes make a pretty good substitute except for the fragrance. Our Texas Department of Transportation even uses crepes, totally unpruned and seldom irrigated, as light blockers on rural divided highways, because the big bushy shrubs can grow to 20-30 feet and are dense enough to block oncoming headlights. We find that sooty mold has to be treated aggressively, but powdery mildew can be lived with. It’s not pretty, but here in the “heat belt” it doesn’t seem to affect the growth or bloom much.

    September 3, 2013 at 11:11 am
  24. Steve Bender

    Hey Camille,
    Is is MY fault the crepe myrtles were the wrong plants planted in the wrong spot? I think not.

    September 4, 2013 at 1:30 pm