What Causes Leaves to Curl on Pepper Plants?
Pepper leaf curl can result from many different problems, ranging from pests and viruses to environmental stress.
Pests
Pests like aphids, thrips, mites, and whiteflies cause leaf curl on pepper plants with their feeding activities. Mature leaves may develop spotted or stippled areas, dry out, or fall off, but leaves fed on during development emerge randomly curled or twisted, depending on the location of the feeding. Many of these pests produce honeydew, a sticky, sweet substance as a result of their sap-feeding– you’ll notice a shiny clear coating of material near feeding sites. These pests are easily treated with insecticidal soap or neem oil. Treat your peppers weekly, when ambient temperatures are below 80 degrees F. (27 C.). When you spray, cover tops and bottoms of all the leaves and branches thoroughly, until the soap runs off the plant tissues. Continue treatment regularly until no more evidence of the pests remain.
Virus
Viral diseases can cause curling leaves on peppers, among other symptoms like yellow spots, rings, or bullseyes on leaves as well as general un-thriftiness. Insect pests carry viral agents between plants, spreading these incurable diseases far and wide. If you suspect a virus, immediately remove the infected plant to help prevent further disease spread and keep pests under control. Viruses aren’t usually present in the soil, so if you catch it early in the season, you may be able to replace the affected plants. Virus-resistant peppers are available from most nurseries for gardens with recurrent virus problems.
Environmental Stress
Environmental problems are often at the root of pepper plants with leaf curl. Pepper leaf curl regularly appears on hot days, during the middle of summer; hot winds combined with low humidity cause leaves to cup in self-defense. If leaves curl only in response to heat, try adding extra water during the middle of the day to keep the plant’s tissues cooler. Herbicides are sometimes responsible for curling leaves. Always be careful where you spray; make sure that there’s no wind and that run-off won’t end up in your garden. Garden products like compost and mulch that have been treated with herbicide can also cause damage on sensitive plants like peppers. If your plant survives the herbicide exposure, it should produce a small crop despite the damage. Be more careful with herbicides in the future.
