Why Does My Gleditsia Tree Look Unhealthy?

Have the leaves been skeletonized or with large holes in them, branches may be webbed?

Was the plant defoliated with branches bearing cocoonlike bags?

Does the trunk or the branches have small holes in them, limbs may die or break off?

Does the trunk or the branches have oozing lesions, branch tips die back?

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

Do the leaves of your Gleditsia have a light powdery coating or patches?

Do the leaves have raised, rusty spots on their undersides?

Webworms can be a serious problem on honey locust. Webworms are caterpillars that feed on leaves and spin silken webs around leaves and stems. Young plants may die and the older ones can be seriously weakened. Break up and remove the webs and spray plants with BTK. Some cultivars, such as ‘Moraine’, show some resistance to webworm damage.

Bagworms are causing these symptoms. They are small, brown caterpillars that feed inside the silky, white bags they create. Handpick and destroy all the bags. If you notice crawling caterpillars you may have to use insecticide as they are really hard to get rid of.

If the trunk or branches have small holes in them the culprits are borers. 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.

Oozing lesions are caused by cankers. Cankers can be caused by several different kinds of fungi. Mildly affected plants will recover if you remove and destroy all affected branches. Heavily affected plants can't be cured and you should remove the whole plant. Avoid damaging your plant with lawnmowers, trimmers or pruning tools because the wounds are the best place for cankers to start.

Your Gleditsia 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.

White, powdery patches on the leaves are caused by the fungal disease - Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the plant by thinning branches. Keep foliage dry when watering. Affected leaves should be cut off and removed.

Raised, rusty spots on the undersides of the leaves are caused by the fungal disease Rust. Leaves may yellow and die. To control this disease, rake up and destroy fallen leaves. Where the problem is severe, spray with copper.

Some environmental issues may have caused your honey locust tree to look sickly. Gleditsia prefers moist, fertile, slightly alkaline soil, but it will tolerate slight drought and salt.