Synergism between Heterodera cajani and Fusarium udum attacking Cajanus cajan

Abstract

During a survey along thc Aligarh-Delhi road in Uttar Pradcsh, certain fields of pigcon pea, Cajanus cajan (L.) Millsp. showed severe wilt symptoms while the incidence of the disease in other nearby fields was not severe even though thc same local variety was grown in all the fields. Soil and root samples collectcd from the fields (of pigeon peas) were processed by appropriate laboratory procedures and the nematodes Tylenchorhynchus vulgaris Upadhyaya ct al., Helicotylenchus indicus Siddiqi and Hoplolaimus indicus Sher were found. The wilt fungus, Fusarium udum Butler was recovered from roots of plants from fields with severe and mild wilt. The cyst nematode, Heterodera cajani Koshy was found only in those fields where there was a high incidence of wilt. Laboratory experiments were undertaken to establish the role of these nematodes in relation to the scverity of disease development.