What Is Wrong With My Sword Beans?

Are the leaves yellowing, wilting and, dying?

Are there any mottled leaves?

Are the leaves curled and yellow?

Do the leaves have silvery pallor?

Are the leaves yellow, stems die back?

Are there singular, or closely grouped circular to irregularly shaped holes in the foliage?

Yellow leaves that wilt and die usually indicate Root rot. Several pathogens can be the cause of root rots. Poorly drained, overly wet soil promotes rot so choose well-drained sites and add organic matter to improve drainage. Remove and destroy infected plants.

Mottled leaves are caused by tomato spotted wilt virus (TSWV). There is no cure for infected plants. Remove and destroy all sword beans plants that have the symptoms. Viruses are spread by aphids and thrips so the best way of preventing the disease is to control these insects.

Distorted, curled leaves are caused by aphids. These insects cluster under leaves and on growing tips where they feed on plant sap. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Pale, silvery leaves, and petals are caused by thrips. They hide under leaves and inside flowers. Severely infested plant parts should be pruned off and destroyed. Control thrips by introducing lady beetles or lacewings. Insecticidal soap helps in severe infestations.

Stem borers are small caterpillars that cause stems to die back. As spring growth begins, you can easily spot borer-infested plants because the leaves look weak and sickly. The easiest control is to cut out and destroy infested plants as soon as you notice them.

Fall armyworm causes irregularly shaped holes in the foliage. Organic methods of controlling armyworms include biological control by natural enemies that parasitize the larvae and the application of BTK spray (Bacillus thuringiensis).

Sword beans are susceptible to soybean cyst nematodes, small plant-parasitic roundworms that attack the root of the plants. Affected plants become stunted, yellowed, and less vigorous. The best control is switching to resistant bean varieties. Rotate corn, oat, and alfalfa which are nonhosts and will significantly reduce the number of nematodes in the soil. When applied at planting, the effect of the nematicides may last long enough to provide an economic yield benefit.