Why Does My Japanese Maple Looks Unhealthy?

Is the foliage yellowing in places, growth is slowed, large seeds are produced?

Have the leaves and shoots blackened, leaves might have moist or brown spots on them?

Does the trunk or the branches have oozing lesions?

Do the leaves and flowers have holes?

Are the leaves discolored, fine webbing may be present?

Are the leaves curled and distorted?

Does the trunk and the branches have holes, tree look weakened, twigs may be dropping?

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

These symptoms usually indicate a fungal disease - Verticillium wilt. This soilborne fungal disease makes leaves yellow, wilt, and fall off before the entire branch dies. Avoid planting trees near strawberries, potatoes, tomatoes, and eggplants as they are susceptible to Verticillium wilt. Soil solarization may prevent the disease.

Your tree 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 to provide good air circulation.

Oozing lesions are caused by canker. Prune out and destroy dead branches and infested areas. Be sure to make pruning cuts at least 3 or 4 inches below the canker and disinfect pruners between cuts. Spray both the healthy and diseased sections of a tree with copper during and shortly after periods of excessive rain.

Holes in leaves and flowers are caused by Japanese beetles. Adults of these insects devour leaves, stalks, and flowers of nearly 300 plant species. Their larvae feed on the roots of the plants. Handpick adult beetles into a can of soapy water but make sure to wear gloves as Japanese beetles are blister beetles. Apply parasitic nematodes to the soil to limit beetle grub populations. Use pyrethrin powder or neem oil as a last resort.

Spider mites are known to cause problems for Japanese maple trees. Hose off plants when symptoms first appear. A strong stream knocks mites off plants and may give control. Introduce predatory mites. For severe infestations, spray plants with insecticidal soap or pyrethrin.

Distorted and curled leaves are caused by aphids. These tiny insects cluster under leaves and on growing tips where they feed on plant sap. Leaves, stems, and buds get distorted and later leaves and flowers drop from the plant. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Numerous borers attack woody plants, mining the inner bark and wood of branches and trunk. Prune off borer-infested branches. If you see borer holes in your trees, probe into them with a flexible wire or inject a solution of parasitic nematodes. After treatment, seal holes with putty.

White, cottony clusters on leaves and stems are caused by mango 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 leaves are covered with small bumps the culprits are scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance. 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.