Management of Fusarium udum Causing Wilt of Pigeon Pea

Pigeon pea [Cajanus cajan (L.) Millsp.] is one of the important legume crops in India, and more than 100 pathogens such as fungi, bacteria, nematodes, and viruses attack this crop, and among which the vascular wilt pathogenic fungus Fusarium udum is economically extremely damaging. Seedling and adult plants show the symptoms of fusarium wilt with yellowing and drying of leaves followed by whole plant wilting. Wilted plants can be easily recognized in the field with wilt patches. Wilt occurs at the seedling stage of plants but is mainly seen at flowering and podding stages. This disease causes significant loss in all the major pigeon pea-growing areas all over the world. Being soilborne, the pathogen enters the plant through the roots and reaches the xylem vessels along with the water transport system and subsequently reaches the stem and foliage. The incidence and severity of the disease along with understanding the host-pathogen interaction are of great concern. There are many traditional strategies as well as chemical and biological approaches for managing the wilt disease in pigeon pea. Lesser emphasis on the traditional strategies and increasing ecological, economic, and social problems arising with excessive application of chemical pesticides emphasize the need to understand molecular interactions between the host and the pathogen and application of biotechnological techniques along with biological approaches for managing Fusarium udum in pigeon pea fields. Also, there is a limited understanding of the inheritance of fusarium wilt resistance in pigeon pea which is greatly affecting crop improvement programs. In this chapter, we have discussed important strategies from traditional to biotechnological with their impact on the management of wilt disease in pigeon pea. We have also discussed the environmental factors such as soil type, temperature, and nutrient availability which have been shown to affect Fusarium population.