Pest and diseases of pigeon peas

Pests

The biggest threat to pigeon peas are gram caterpillar, the red gram plume moth and the gram pod fly. There are no effective control methods against these pests. Thrips cause premature flower drop but there are chemicals that can control them. The caterpillar of the spotted borer can cause serious damage and the blue butterfly caterpillar and the gram caterpillar can also be troublesome. Leafhoppers and pod borers are of particular importance as  they cause seere leaf curling and are most likely the vector of a virus disease. In East Africa the bollworm, or gram caterpillar and the spotted pod borer can cause severe economical damage. Pulse beatles are a serious pest during the post harvest stage.

Diseases

The most important and widespread disease of pigeon peas is wilt. Fusarium oxysporum f. Sp udum, which is soil-borne and affects the plant at all stages of its development. Soil temperatures between 17-20°C (62-84°F) favour pigeon pea wilt and it is usually more prevalent in the later part of the growing season. A rotation of 3-5 years is required to free soil of infection.

Minor diseases of pigeon peas in India include a leaf slot cause by Cercospora indica, stem blight cause by Phytophtera cajani and stem canker Diphodia cajani. In addition a bacterial leaf spot and stem canker cause by Xanthomonas cajani is common during the summer in Maharashtra, when the relative humidity is between 80-90% and temperature between 24-31°C (75-88°F).

In the West Indies a collar rot and stem canker are serious, especially when pigeon peas are grown as a perennial crop. The causal organism is reported to be Physalospora cajanae, but it is similar to the disease that has also been ascribed to Diplodia cajani and Phoma cajani. Rust, Uredo cajani is also reported to be troublesome. In addition a root rot, Rosellinia sp., is sometimes a problem, especially when the crop is grown in soil where the roots of the previous crop remain. In Africa basal stem rot cause by Macrophomina phaseoli is of some economic importance. Leaf spots cause by Cercospora sp. and  Colletotrichum cajanae ¹ and downy mildew, Leveillula taurica, also occur in many areas where pigeon peas are grown and frequently reduce productivity.

Viruses

Several virus diseases affect pigeon peas, namely pigeon pea mosaic. it can cause almost complete crop failure. The vector reported to be an eriophyid mite, but recently it has been suggested that may be transmitted by nematodes.

1. Featured image: David B. Langston, University of Georgia, Bugwood.org – This image is Image Number 5076072 at IPM Images, a source for agricultural and pest management pictures operated by the Center for Invasive Species and Ecosystem Health, Colorado State University, USDA CSREES and the Southern Plant Diagnostic Network.