Leaves Curling on Strawberries

Powdery Mildew

• Powdery mildew is a fungal disease that causes strawberry leaves to curl upward. The white powdery growth that usually makes this disease easy to identify in other plants isn't as easy to see on some strawberry cultivars. Look for yellow or reddish spots on the lower surface of the leaf. As the disease progresses, the spots will also appear on the upper surface. Infected berries may be malformed or have a tan or rusty pink surface, and some berries may be cracked. Monitor your plants for symptoms of this disease and apply fungicides as soon as symptoms appear.

Verticillium Wilt

• A fungus that can survive in the soil for more than 25 years causes Verticillium wilt. Symptoms include wilting leaves that turn reddish yellow or dark brown. New leaves are stunted and curl up along the mid vein. Brown or dark blue streaks may appear on the runners and roots. Because symptoms are similar to several other strawberry problems, a diagnosis can only be made by a lab culture. Plant resistant cultivars like Catskill, Blakemore, Delite, Earliglow, Sunrise or Tennessee Beauty. Plant strawberries in well-drained soil and avoid wet spots. Don't let weed hosts like lamb's quarter, velvet leaf or pigweed grow near your plants. Don't use fertilizers with high levels of nitrogen. Fumigating the soil can help, but it's expensive.

Cyclamen Mite

• Cyclamen mites are invisible to the naked eye. Symptoms that your plants are infested with them include crinkled and deformed leaves, or leaves that curl upward. Flowers may be distorted or dead. Control mites by submerging plants in water at a temperature of 110 degrees F for 30 minutes, prior to planting. A hand sprayer can be used to soak leaves and flowers of infected plants in the garden. Some miticides are also available.

Aphids

• Several aphid species attack strawberries, causing crinkled and curling leaves or leaves with yellow spots. In addition, aphids excrete a sticky, sweet substance called honeydew that attracts the growth of black sooty mold on strawberry leaves. The shed skins of aphid nymphs can often be found sticking to the fruit. Aphids are small insects that vary in color, depending on the species, but most aphids that attack strawberries are yellowish or pale green. Several natural enemies, including the green lacewing larvae and the syrphid fly, usually keep aphid populations from becoming too big. Insecticidal soaps and neem oil can also be used for control.

Other

• Calcium and boron deficiencies can cause strawberry leaves to curl or become crinkled. Exposure to the 2,4-D herbicide can also cause curled leaves. This is usually a temporary condition that plants outgrow. Infestations of microscopic worms called nematodes cause strawberry leaves to become reddened and to curl. In addition, buds and flowers become deformed and plants are stunted. Control nematodes by fumigating the soil and only planting certified stock.