Why Does My Azalea Look Unhealthy?

Are the leaves mottled and do they have shiny, black flecks on the undersides?

Do the leaves have notched edges?

Are the leaves yellow and wilting and branches may drop off?

Do the leaves have spots?

Do the petals have pinhead-sized spots on them and blooms may rot?

Do the stem tips die as the leaves turn brown and wilt?

Are the leaves yellow and covered with small bumps?

Have the leaves yellowed?

Are the leaves mottled yellow?

Have the leaves been tunneled?

Small tar-like spots on undersides of the leaves are caused by lace bugs. Remove debris in springtime and in fall to deter overwintering of these small insects. If the infestations are severe you can control them by spraying pyrethrin, insecticidal soap or superior oil on your azaleas.

Notched edges on the leaves are caused by Black vine weevils. The wingless brownish-black adults feed on the leaves and bark and can kill branches. To control them, spread a drop cloth around your plant and shake it so the adults drop. You can get rid of them after that. Spray leaves several times with pyrethrin for major infestations.

These problems are caused by Rhododendron borers. These small, clear-winged, wasp-like moths lay eggs on leaves, twigs, and bark. Their larvae burrow into the weakened stems and branches. Control borers by pruning and destroying affected branches. Seal the cut branches with putty or grafting wax.

Several kinds of fungi cause leaf spots on azalea. Spots may enlarge rapidly, especially in wet weather. Destroy infected leaves. Spray plants with sulfur to prevent the disease from spreading, especially if the weather is wet. Prevent problems by thinning plants to provide good air circulation.

Flower petal blight is a disease that often causes problems for azaleas. Remove and destroy infected flowers and branch tips. Rake debris from around the base of the plant and replace it with fresh mulch.

The cause is probably a condition called Dieback. Besides causing leaves to brown, roll, and wilt, dieback may kill stem tips and cause cankers to form on stems. Avoid dieback by keeping plants healthy, with regular watering and good winter protection. Prune out diseased tips several inches below the damaged areas. Spray the plant with Bordeaux mix after the plant blooms and again 10 days later.

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.

Chlorosis in azalea is most often caused by high soil pH. Restore soil acidity by applying 2-3 pounds of sulfur per 100 square feet of growing area. Mulching with evergreen needles or chopped leaves will help maintain the proper pH.

Leaves mottled yellow are caused by whiteflies. These tiny, mothlike flies and their larvae feed by sucking plant juices. Whiteflies secrete honeydew, a sugary substance that makes leaves sticky to the touch. Control whiteflies by eliminating garden weeds and by introducing green lacewings in the garden. Spray infested plants with insecticidal soap every 3 days for 2 weeks.

These symptoms are usually caused by 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 in fall because it might contain overwintering leafminers. Introducing parasitic wasps is a very effective method of controlling leafminers.

If the leaves have green, white or brown galls on them, the most likely cause is the fungal disease Azalea leaf gall. Pick off and destroy infected leaves as soon as you spot the galls.