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A survey of 116 districts of nine lentil growing states covering 603 farmers' fields revealed a range of 0.7-9.3% mean plant mortality at reproductive stages in different lentil growing states of the country. The overall mean mortality was 6.3%. The main pathogens found associated with plant mortality at this stage were Fusarium oxysporum f. sp. lentis (62.0%), Rhizoctonia bataticola (25.2%) and Sclerotium rolfsii (9.8%). The minor involvement of 1.8% was that of F. solani, F. chlamydosporum. F. equisetii, and R. solani. For the first time a national scenario of lentil wilt-root rot incidence at the crucial reproductive stage and their associated pathogens is reported here. [ABSTRACT FROM AUTHOR]

Lentil (Lens culinaris Medik.), the second most important rabi pulse crop of India, suffers heavy plant mortality due to wilt, root rot and collar rot at different stages of crop growth. Congenial soil temperature and moisture during early crop growth, winter rains and terminal drought favour invasion of the crop by many root-invading pathogens. The present study based on 265 samples from 76 districts of seven states of India revealed the involvement of 12 different fungi with the highest association of 30.8% of Fusarium oxysporum f. sp. lentis followed by 17.5 and 15.7% by Rhizoctonia bataticola and S. rolfsii, respectively. Percentage involvement of F. oxysporum f. sp. lentis and R. solani with lentil roots increased with the increase in crop age while that of R. bataticola decreased. S. rolfsii was found to be associated at maximum during the vegetative growth phase. It was further observed that F. oxysporum f. sp. lentis, R. bataticola. R. solani, S. rolfsii and Alternaria sp. were found universally associated at all moisture levels; F. oxysporum f. sp. lentis slightly increased with lower moisture availability while R. solani and R. bataticola were higher at high soil moisture. Other fungi found associated with wilted lentil roots were F. chlamydosporum, F. equisetii, Aspergillus, Penicillium, Helminthosporium, Rhizopus and Trichoderma species. The overall mean plant mortality was 3.5% up to 30 DAS, 7.7% between 30 and 90 DAS and 16.8% above 90 DAS. Similarly, it was 2% at low moisture, 18.5% at optimum moisture and 17.7% at high soil moisture. [ABSTRACT FROM AUTHOR]

Twenty four isolates of Fusarium oxysporum f. sp. lentis (Fol,) collected from different lentil growing areas of the Gangetic plain showed variation with respect to cultural and morphological characters. The extent of genetic diversity was evaluated using a set of 40 RAPD primers and 12 SSR primer pairs, out of which 25 RAPD primers and 9 SSR primer pairs revealed polymorphisms among the isolates. A total of 217 polymorphic fragments for the RAPD primers and 22 for the SSR primers were scored. Genetic similarity between each the isolates was calculated using the Jaccard similarity coefficient and cluster analysis was used to generate a dendrogram showing relationship between them. The isolates could be grouped into two subpopulations based on RAPD and SSR analysis. Results obtained indicate that there is little genetic variability among a subpopulation of Fol as identified by RAPD and SSR markers. Also, results indicated that the Fol isolates differ in their aggressiveness on the susceptible lines and that there is no apparent correlation between geographical origin and aggressiveness of isolates. [ABSTRACT FROM AUTHOR]