What Is Wrong With My Shadbush?

Are the leaves pale on their upper side and are there any dusty blisters on the undersides?

Are the leaves covered with white powder?

Did the flowers and leaves suddenly blackened, and the tips of growing shoots bend over?

Are there any silky caterpillar tents in the branches in late summer?

Are the leaves eaten, conspicuous tawny egg masses are present?

Are there any irregular galls on undersides of leaves, leaf stalks, and/or new shoots?

Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from below to keep foliage dry. Any affected leaves should be cut off and removed. The appropriate fungicidal spray will protect your plant from further infections.

These symptoms indicate a bacterial disease Fire blight. Control fire blight during the growing season by pruning off branches a foot below infected sections. Between each cut, dip pruning shears into isopropyl alcohol or a 10 percent bleach solution to prevent spreading the disease as you prune.

Fall webworm is a caterpillar that makes silky tents during Fall. Fall webworms are usually held in check by songbirds, yellow jackets, wasps, and rodents. You can easily remove the webs when they occur in trees. Insecticides are seldom necessary for fall webworm, especially in trees, and should be considered only if the infestation is heavy. Bacillus thuriengensis (BT) can be used when the caterpillars are small, but it will not provide satisfactory control once the webs are large.

Gypsy moth caterpillars sometimes mass on the foliage and devour it, defoliating the tree. Mature caterpillars have 5 pairs of blue spots and 6 pairs of red spots along the back. In light infestations destroy eggs or pick caterpillars by hand, in more severe cases spray plants with BTK or pyrethrin as the last resort.

Serviceberry gall mite is a known pest of shadbushes. Monitor for the presence of gall mites by regularly checking the undersides of leaves. Miticides need to be applied protectively as once the mites have entered the leaves, chemical control is ineffective.

If any frass and tunnels are appearing on a lower part of the trunk the culprits are borers. The most important insect borer attacking shadbushes is a roundheaded apple tree borer. Preventive measures are the best control for these pests like avoiding wounding the trunk with lawnmowers, string trimmers, or pruning equipment because these injuries provide an easy entrance for borers. If borers do strike, try cutting them out of the trunk with a sharp knife. Remove and destroy seriously infected bushes.