WILT DISEASE OF PIGEON PEA [Cajanus cajan (L.) Millsp.] CAUSED BY Fusarium oxysporum f. sp. udum

Variation in the expression of symptoms of pigeonpea wilt occurs at different levels. These levels include differences among fields, genotypes of pigeonpeas and pathotypes of the wilt causing fungus. Field incidences of the disease reported by Biswas et al. (2020) ranged from 4.50 to 26.00%. Anjad and Sanawad in Madhya Pradesh recorded the highest incidences. Pigeonpea wilt is widely distributed and occurs throughout most of the growing areas of pigeonpeas. Although, for this study, data from West Bengal and Madhya Pradesh were used, it was observed that means computed from site counts from both the states were closely related, thus underscoring the need to analyze site counts from various localized areas rather than interpreting data from states in general. In the greenhouse studies conducted by the author, wilt symptoms were least observed in plants of ICP 8863 and Richa. In the later study, symptoms in plants of ICP 9174 were less in the presence of a 60 isolate panel of the wilt fungus (Ravikumara et al. 2022). The two investigations identify the importance of the test context for resistance evaluation. ICP 8863 differed from the counted greenhouse data and thus extrapolations based on limited testing data are inadequate. Subsequent studies must incorporate coreartum checks and representatives of F. udum, clear delineation of reactions, and collaborative field and laboratory studies. Rational integration of pathogen management with pathogen diagnostic tools and disease risk assessment in the field may facilitate determination of resistant plant populations and better interpretation of resistance in the field (Sharma et al., 2016; Srivastava et al., 2023). In the meantime, improvement in resistant plant populations may be possible through integration of several complementary interventions. The desired effect, i.e. long term integration of stable host resistance with other management practices, may be attainable. Heterogeneity may exist across Fusarium wilt pathosystems, and, thus, it may not be valid to assume that integrating management practices across various Fusarium wilt pathosystems will not be effective (Dave and Ingle, 2021).  

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