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

August 22, 2013 | By | Comments (186)
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. Charlie

    I am somewhat surprised that nobody has replied to my (2) comments in this thread. As Myrtles are so common, I thought that someone might have had this Myrtle problem and already knows how to fix it.

    June 23, 2017 at 3:14 pm
  2. Angeline Grigar

    Just planted some small myrtles. They now have black mold on all the leaves. The plants have only been planted a month ago.I need help as These were given to me on Mothers Day.

    June 23, 2017 at 9:33 am
  3. Charlie

    Nobody has replied to my earlier post (from today) and it looks like this “blog” offers no way to edit my post, so here’s more info. The 2 red Myrtles have lost a lot of their leaves and they have leaves that have turned kind of an orangy-yellow. I see no sign of fungus or soot. The leaves are not really spotted. The trees just look like it is late Fall and the tree thinks winter is about here. Just not doing well while other Myrtles n the area are looking fabulous. What’s wrong?

    June 20, 2017 at 5:48 pm
  4. Steve Bender

    Tom,
    This probably has something to do with the weather. I don’t think this is a serious problem. The leaves should slowly turn green again.

    June 20, 2017 at 3:10 pm
  5. Charlie

    Crepe Myrtles not doing very well. I live south of Austin, TX., and I planted 3 Crepe Myrtles in my Bermuda yard about 5 years ago – 1 large white, 1 Red Rocket, and 1 Dynamite (red). Actually, a nursery planted my Dynamite. All 3 of the Myrtles have grown well in size, and in previous years all 3 of them flowered beautifully. This year, even though the 3 Myrtles have had enough water and lawn fertilizer, and sun, they are not doing well. The large white tree has some flowers and many big pods of seeds, but at least half of the seed pods fail to flower. One of the red Myrtles has no flowers and no seed pods. The Red Rocket has 2 flowers and almost no seed pods. Both of the red Myrtles have too few leaves and some of those leaves have turned beige/yellow and they fall off easily. Other red Myrtles in my neighborhood are doing very well with nice green leaves and red flowers. I can take a photo if you need it. What to do to fix these trees?

    June 20, 2017 at 12:24 pm
  6. Bonnie

    Steve; my Crepe myrtle has string ling growth all over the trunk. The brush off, but what are they and how do I get rid of them?

    June 18, 2017 at 4:17 pm
  7. Beverly Clay

    I love you Grumpy!I relocated from the frozen North to the sunny South and I got lost in the differences between soil types, plants and pests of the area. You have helped me tremendously. I will faithfully continue to read your posts.

    June 17, 2017 at 3:54 pm
  8. Tom hughes

    One section Of leaves have turned purple???

    June 10, 2017 at 12:58 pm
  9. Steve Bender

    Linda,
    If it wipes off easily, I’d just keep wiping it off.

    June 6, 2017 at 10:52 am
  10. Robyn Fergeson

    One of my four standard crape myrtles has a growth like a huge callus on the upper trunk where two branches come out from the main trunk. It’s really ugly! Not sure what it is or what to do about it.

    May 26, 2017 at 8:41 pm
  11. Melody Rains

    I have little white crusty spots at the tip of the leaves on my crepe myrtle

    May 26, 2017 at 2:34 pm
  12. Deborah Mather

    My crepe Myrtle has no leaves. Looks like buds are forming but very slowly…

    May 26, 2017 at 12:45 pm
  13. Linda L Goodson

    My crepe myrtles have a white, I’m guessing, fungus on the main trunks of the trees and at the joint where the leaves come out from the branch. It actually looks like someone has used an eye dropper and just put a tiny drop of something white in these places. It is not a powdery white fungus like I’ve seen on other plants. You can just wipe it off and it leaves no trace. It leaves no trace What should I use to get rid of this? The trees are nice and green….just have those weird little drops of something white like I explained. Thank you..
    Linda Goodson
    Fort Smith, AR

    May 22, 2017 at 2:17 am
  14. Steve Bender

    K Hale,
    Sorry, but I don’t have a solution for that.

    May 13, 2017 at 11:57 am
  15. K Hale

    My Carolina Beauty crepe myrtle is in full sun and blooms beautifully. The problem is the blooms do not last long. They fall off if it rains! The tree is about 5 years old. Any suggestions?

    April 24, 2017 at 8:06 am
  16. Steve Bender

    Ginger,
    The sooty mold grows on sticky honeydew secreted by insects that suck on sap. Get rid of the bugs and you won’t have the mold. Try spraying your tree according to label directions with horticultural oil now. Repeat this in about two months.

    February 23, 2017 at 8:04 am
  17. Ginger Rhamey

    Several of my crepe myrtles have a black sooty look on some of the limbs
    What is it and how do I treat it

    February 16, 2017 at 7:26 am
  18. Steve Bender

    Laura,
    It sounds like some kind of borer, though thankfully not Asian ambrosia beetle. If you’re worried about them, apply the soil drench systemic in spring. It should not harm any bees.

    February 1, 2017 at 8:59 am
  19. Laura McLeod

    Steve:

    First, thank you for your response. To answer your question, no there are no indications of an Asian ambrosia beetle infestation. I am certain of this because we had such occur a few years ago with some of our crepe myrtles on another part of our property. They were very healthy trees and have since recovered. I can send a few photos of the damage taken before I treated the wounds with a sealan, but I need to know how to do thatt.

    January 25, 2017 at 9:40 am
  20. Steve Bender

    Laura,
    Do you see anything that looks like toothpicks of sawdust sticking out from the trunk and branches. This indicates infestations by the Asian ambrosia beetle, and insect that carries with it a deadly fungus. Application of a soil drench systemic insecticide may help unless the fungus has spread too far.

    January 25, 2017 at 8:05 am
  21. Laura McLeod

    What’s eating our crepe myrtle’s cambium layer? The insect leaves long thin bald lines and a fine powder residue in its wake. We can provide photos of the damage if desired. The tree is now dormant and have not been able to seen the culprit, but would like to prevent its return in the spring! Is a systemic drench appropriate; but don’t wish to harm bees during the bloom period?

    January 15, 2017 at 3:34 pm
  22. Steve Bender

    Judy,
    These growths are called lichens. They are very common, use the trunks and branches only for support, and cause no harm.

    December 28, 2016 at 9:28 am
  23. Judy Taylor

    My crepe myrtles have just developed a gray- green feather- like growth on the trunk … It looks like the stuff that grows on live oak trees in the southeast … Is this a problem

    December 21, 2016 at 1:35 pm
  24. Karen Beard

    Love the humor in the posts. Keep it up!

    October 27, 2016 at 8:08 pm
  25. Steve Bender

    Teresa,
    This is a fungus called black mold that grows on the sticky honeydew secreted by sucking insects such as aphids. Kill the insects and the mold goes away. Spray your tree with neem oil, horticultural oil, or insecticidal soap according to label directions.

    September 28, 2016 at 8:09 am
  26. Jan Champagne

    I live in Northeast Pennsylvania. I planted a Crape Myrtle two,years ago. I have seen many planted and thriving in our area. I do put a layer of mulch and wrap it for winter protection. The question I have is both years, I am not sure whether I got to it in time with protection, but the leaves had already dried up and dropped off. The first year, the plane came back at the ground area, the second year, the leaves came back on the woody stems and it bloomed a little. Is it normal for the leaves to just dry up and fall off? Thank you.

    September 25, 2016 at 9:21 am
  27. leonard williams

    my crepe myrtle has leaves falling and on all the limbs and main trunks are whit e spots. looks like tiny mot h balls all over them, hope my tree isn’t dieing.

    September 19, 2016 at 10:48 am
  28. Grumpy Gardener

    Teresa,
    This is probably black mold that’s growing on honeydew secreted by feeding aphids. Spray your plant according to label directions with horticultural oil.

    Sheree,
    This must be due to growing conditions, but I can’t give a specific answer.

    September 17, 2016 at 4:36 pm
  29. Teresa Myers

    What is wrong with my Crape myrtles?
    The bark is black

    September 17, 2016 at 3:18 pm
  30. Sheree Kristinek

    My crepe myrtle has buds all over it but they won’t open. This has happened for several years.

    September 3, 2016 at 2:09 pm
  31. Grumpy Gardener

    Carolyn,
    The white film is powdery mildew. See problem #2 above.

    Sallie,
    The gardenias have black mold. See problem #1 above.

    August 31, 2016 at 11:13 am
  32. carolyn wrigley

    My plant is trying to bloom and has some but the booms have a white film over them. What can I do and what is it

    August 23, 2016 at 12:25 pm
  33. Sallie

    what about gardinas plants hat have black leaves what do you put on them? I live in Central FL

    August 20, 2016 at 1:57 pm
  34. Steve Bender

    Bruce,
    Yes.

    August 18, 2016 at 1:34 pm
  35. G. Bruce Makowski

    My crepe myrtle is planted in the open sun with lots of breeze and its leaves are turning color and dropping? Do you think Cercospora leaf spot is the problem?

    August 13, 2016 at 9:09 pm
  36. Grumpy Gardener

    Martha,
    I’d move your crepe myrtle to a spot with full sun this fall. In its place near the house, what about a Japanese maple?

    August 11, 2016 at 10:19 am

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