Why Does My Lilac Look Unhealthy?

Do the leaves of your lilac have powdery white patches on them?

Do the leaves have tan or brown blotches or serpentine tunnels?

Do the trunk or branches of your lilac have small holes in them, causing the limbs to die and break off?

Are the leaves on your lilac completely yellow and covered by small bumps?

Have the leaves of your lilac wilted and discolored?

Do the leaves of your lilac have spots on them?

Are the leaves pale and drop early while the branches wilt and die?

Have the leaves been skeletonized or with do they have holes in them?

Are the shoots clustered tightly?

White, powdery patches on the leaves are caused by a fungal disease - Powdery mildew. Powdery mildew usually appears in damp places. Thin your plants to ensure good airflow. Water the plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.

These symptoms are usually caused by insects - Leafminers. These tiny pale green fly larvae feed between the upper and lower surfaces of the leaves. Prune off and destroy all infested leaves. Remove debris during the fall because it might contain overwintering leafminers. The weekly application of insecticidal soap should keep their numbers low. Also, introducing parasitic wasps is a very effective method of controlling leafminers.

These symptoms usually indicate caterpillars - Borers.

Yellow leaves covered by small bumps are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance with yellowish blotches on the upper leaf surfaces. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

These symptoms usually indicate either a bacterial or a fungal disease - Blight. Prune off all infected branches during the dormant season. Disinfect pruners after each cut in a 10% bleach solution. In spring, spray twice with Bordeaux mix at 10-day intervals, starting when the leaves first unfold.

Leaves with spots usually indicate either a bacterial or a fungal disease - Leaf spot. Remove and destroy all infected leaves. Thin plants to increase airflow. Avoid wetting leaves when watering. Clean up all plant debris around your plants to remove overwintering sites.

These symptoms indicate fungal disease - Wilt. If plants are affected by this fungus, prune off dead and diseased branches. Feeding with a high-nitrogen fertilizer may help plants recover. Remove and destroy badly infected shrubs, and don't plant lilacs in the same soil.

These symptoms usually point to some species of caterpillars. Several kinds feed on foliage, including tent caterpillars and webworms. Control all of these pests by manually destroying their nests or egg cases, spraying leaves with BTK at the first sign of damage, or, as a last resort, applying pyrethrin spray.

Tightly clustered shoots are caused by Witches' broom. This problem is usually not serious; merely prune out and destroy the dense, bushy growth.

Poor growing conditions may have caused your lilac's unhealthy look. Too much nitrogen promotes soft, leafy vegetative growth. Excess irrigation can reduce blooms and encourage soft growth.