Crape myrtles are a wildly popular landscape tree in North Carolina. You can easily find them in parking lots, business landscapes, and home gardens. In fact, there is a bit of an issue with them being overused in the Southeast, with some municipalities reporting that more than 25 percent of their “trees” are crape myrtles.
While we love these almost bullet-proof trees for their beautiful flowers in the heat of summer, their attractive smooth bark, and ability to survive in some pretty poor sites, they are not perfect. As the heat and humidity return to the Southeast, be on the lookout for powdery mildew on your prized crape myrtles!
This is a close up photo of the powdery mildew fungus infecting the leaf of a crape myrtle. You can see the leaf is starting to curl as the fungus infiltrates into the tissue. Photo by James K. Douch (CC BY-SA)
What is Powdery Mildew?
Powdery Mildew is a species of fungus (Erysiphe australiana, previously E. lagerstroemiae) that specifically targets the young, tender foliage of crape myrtles (genus Lagerstroemia) under hot, humid, stressful conditions. It makes the tips, leaves and flower buds look like they’ve been sprinkled with baby powder.
Unlike many other fungi that require wet leaves to spread, powdery mildew thrives when the air is "soupy" and humid at night, but the leaf surfaces are dry during the day. This is why you often see it strike during our sweltering, rainless summer stretches.
There are other species of fungus that cause a powdery look on plants, but they are usually a different fungal species.
This year (2026), so far, has been dry and cool, which are conditions the fungus doesn’t prefer. But it is May, and this fungus usually strikes in June and July, just as the flower buds are forming and swelling.
Powdery mildew can make foliage look unattractive and distorted, and even cause stunting of foliage. The worst part is that bad infestations can impact healthy foliage and even flower buds. The fungus can infect flower buds, causing them to abort or fail to open. This can ruin the flamboyant floral display we wait all year for.
Flower buds can be severely impacted by crape myrtle powdery mildew if left untreated. This can result in poor flowering or total flower bud drop. Photo by Cat Chang (CC BY-NC)
Prevention is Worth a Pound of Cure
Variety Selection: The best way to get the perfect floral show without all that work is to plan ahead. When you are at the nursery or design phase of your landscape, make sure you select a variety that is resistant to powdery mildew. Many of the cultivars developed by the National Arboretum, most of which are named after Native American tribes, are disease resistant and come in all shapes, sizes and colors.
Site Selection: Crape myrtles are tolerant of a wide range of growing conditions, but they prefer full to part sun. Shade slows down the drying process and stresses the tree, making it a "sitting duck" for fungus.
Air Flow: Make sure your crape myrtle is in a site where there is good air flow and make sure to prune any root sprouts and dense growth that can crowd the canopy. Powdery mildew prefers to grow on younger tissues, but can infect older, more mature tissues when conditions are optimum for the fungus, but not the plant. Finally, avoid heavy topping, aka "Crape Murder". This practice forces the tree to put out lush, succulent growth that is highly susceptible to infection.
Don't Over-fertilize: Similarly, avoid over-fertilizing with high-nitrogen lawn fertilizers near your trees, as this can also cause a flush of lush growth that is susceptible.
Crape myrtle foliage becomes spotty and white when powdery mildew takes hold. This is an extensive infection that may require chemical treatment. Photo by nthumphrey (CC BY-NC)
What Can I Do to Treat It If My Tree Gets It?
Be on the lookout for powdery mildew on those sweltering summer days, especially as the flower buds form and swell. There are control options if you find your crape myrtle contracts powdery mildew, but early action can make it easier to control. For small outbreaks on a few branches, just remove the infected tips and throw them into your trash (not your compost pile!).
If the infection is severe, you can utilize a fungicide, horticultural oil or neem oil; and there are many options for control. Please refer to the NC Ag Chem Manual for specific options. The challenge with chemical options is making sure you can get proper coverage of infected materials. If your tree is more than ten feet tall, getting proper spray coverage is difficult. In these cases, it may be more cost-effective to hire a professional tree care company or focus on better cultural practices for next year.
Crape myrtles are excellent landscape plants that give us a rare, flamboyant show in the sweltering months. Even though they are tough plants, they still need us to keep a close eye on them, especially during stressful times. These beautiful landscape plants will thrive and give you a summer show with just a little TLC from a mindful gardener.
Connecting with the Author
Amanda Bratcher is the horticulture agent with N.C. Cooperative Extension- Lee County Center. You can reach out to the office at 919-775-5624 for more information or questions regarding this article, but also any other questions about your garden, farm, land or plants! We’re here to help! You can check out our website's events page for more information and to register for upcoming programs.
This article originally appeared in The Sanford Herald. You can read more articles from the Herald here: https://www.sanfordherald.com/.
