What Is Wrong With My Weigelia?

Are the branches and the foliage encrusted with small bumps?

Do the upper leaves have irregular tan spots?

Do the leaves and branches have white, cottony clusters on them?

Does the whole plant look stunted, leaves have been discolored?

Do the stems have swollen, tumor-like growths on them?

Have the tips of the branches turned brown and died?

Do the leaves have moist or brown spots on them?

Are the leaves yellow and wilting?

Scales are known pests of weigelias. 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 dormant oil just before the growing season.

Sunken and discolored spots on upper leaves of weigelia are caused by Four-lined plant bugs. These small yellow bugs have 4 black stripes on their wings. They are active in early summer. Control them by handpicking. Use pyrethrin on leaves for severe infestations.

White, cottony clusters on leaves and branches are caused by mealybugs. These tiny insects are covered with a fluffy white coating. They feed by sucking plants sap. They produce sticky substance honeydew which makes leaves sticky. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

If the whole plant looks stunted, and the roots have tiny galls on them the culprits are Root-knot nematodes. Prevent root-knot nematodes by applying chitin or introducing parasitic nematodes to the soil before planting. Solarizing the soil also helps in preventing root-knot nematodes. Adding lots of compost to the soil will encourage fungi that attack nematodes.

Bacterial disease Crown gall causes wartlike swellings on stems of weigelia. Gall bacteria are introduced into shrubs that are vulnerable due to wounds. If the plant is only slightly infected, prune off diseased growth. Destroy severely infected plants and avoid replanting weigelias or any susceptible plant species in the same spot.

Twig blight is a disease that is known to occasionally cause problems for weigelias. Prune off affected parts back to live wood. Spray plants with copper fungicide or lime sulfur fungicide when symptoms first appear and then every 10 days in wet seasons. Avoid overhead watering.

Your weigelia might be suffering from Anthracnose or some other fungal leaf spot. Spots may enlarge rapidly, especially in wet weather. Destroy infected leaves or plants. 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.

Soil-dwelling fungi cause root and stem rot of weigela. Typically, shrub stems are attacked at or near the soil level. Foliage turns yellow, wilts, and dies. Remove and discard the infected shrub, or cut away affected plant parts with a clean, sharp knife or razor blade. Disinfect tools after use with household disinfectant. Keep the garden clear of old plant debris and keep mulch away from stem bases.

Although Weigelas are generally hardy in areas where winter temperatures may dip as low as 0° F, the tender tips of their branches suffer frostbite at these temperatures and die back. This does not permanently harm the shrub. In the spring, improve the appearance of the shrub by clipping off the dead branch tips before bloom time.