What is wrong with my box elder?

Are there any yellowish-green spots on the leaves that later turn completely yellow; numerous small, raised, black spots may have developed inside the yellow area?

Are the leaves covered with white powder?

Are the older leaves turning yellow and wilting, an overall decline in plant vigor is apparent?

Are there wet, sappy areas on the bark of the main trunk, which may crack?

Are the leaves curled, distorted, and yellow?

Are there any clusters of dark brown or black insects relieved by red wing veins and markings on the abdomen?

Are the leaves discolored, foliage may be webbed?

Are the leaves and twigs covered with small, armored insects?

Are the leaves yellow, branches, and leaves are covered with small bumps?

Tar spot is a fungal disease caused by Rhytisma acerinum. As maple leaves develop to full size, light to yellowish-green spots develop in the infected areas of the leaves. The area becomes yellow, with numerous small, raised, black spots forming within the yellow area. Rake up and destroy leaves in autumn to reduce the amount of inoculum for the following spring. In nursery settings, protective fungicide applications may be warranted as leaves develop in spring.

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. Any commercial fungicidal spray will protect your plant from further infections.

These symptoms indicate fungal disease Verticillium wilt. Verticillium infects a wide range of plant species. Destroy all infected plants, as there is no cure. Prevent problems by presoaking seed in a 10 percent bleach solution.

Larvae of flatheaded borers tunnel beneath the bark, causing wet, sappy areas on the bark of the main trunk. Boring may kill limbs or entire trees. Providing proper care and protecting landscape plants from injury will make them less attractive to the borers. Avoid pruning spring-summer while adults are active. Properly dispose of infested wood material, as beetles may emerge from logs and attack nearby plants.

Distorted, curled leaves are caused by aphids. These tiny insects can vary in color, green, pink, black, gray to completely white. They 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.

Both nymphs and adults of boxelder bugs remove plant fluid from newly developing leaves that may result in distortion of the foliage. Severely infested foliage may appear chlorotic (yellow). In addition to foliar feeding, boxelder bugs may also damage flowers, tender twigs, and seeds. n application of a registered insecticide formulation for non-edible ornamental trees or shrubs directed to the foliage can be made in early summer when nymphs are exposed and feeding on seeds and other soft host plant tissue.

Spider mites are known to cause problems for box elder trees. You can control spider mites by spraying plants thoroughly with water 2-3 times a day for several days. For severe infestations, spray plants with insecticidal soap or pyrethrin.

Small, armored insects on leaves and twigs are armored 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.

Soft scales are known to attack box elder trees. 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.

Notched edges on leaves are usually caused by insects - Fuller rose beetles. This small, grayish-brown beetle has a cream-colored stripe on each side of its body. It feeds on foliage usually at night time. Larvae usually feed on roots. You can handpick the adults as they hide in foliage during the day. The application of sticky substances at the base of the plant should prevent adults from climbing up the plant. Introduce parasitic nematodes to the surrounding soil to control larvae.