Identification and molecular characterization of Fusarium spp. causing wilt, root and crown rot diseases in green lentil in Yozgat province and determination of the reactions of some varieties

In the study conducted in lentil fields of Yozgat province during 2022–2023, surveys were carried out in 83 different lentil fields, and 679 diseased plants showing disease symptoms were used in isolation studies. Disease prevalence was determined as 100%, with an average disease incidence of 16.9% and a disease severity of 38.6%. The highest disease incidence and severity values were recorded in the districts of Yozgat Central, Sorgun, and Şefaatli. Among 723 fungal isolates, 95.4% belonged to the genus Fusarium; the most frequently isolated species was F. oxysporum (59.5%), followed by F. graminearum (15.8%), F. culmorum (10.2%), F. acuminatum (5.5%), and F. solani (4.4%). For morphological characterization of the isolates, colony color, conidia type, and size were examined. In molecular analyses, the ITS region was amplified by PCR, sequenced, and compared with GenBank data for species-level identification. Phylogenetic analyses showed that the isolates were genetically separated among species such as F. oxysporum, F. culmorum, and F. graminearum. In pathogenicity tests conducted under greenhouse conditions, the lentil cultivar 'Kayı-91,' known for its susceptibility to the disease, was used. The first symptoms were observed approximately 30 days after sowing, as yellowing of the lower leaves; in some isolates, disease severity exceeded 90%. Notably, isolates F. oxysporum (YBUFo4), F. culmorum (YBUFc1, YBUFc2), and F. graminearum (YBUFg1, YBUFg3) were classified as highly virulent. In contrast, F. acuminatum isolates exhibited low virulence. Based on the obtained data, the isolates were divided into five main virulence groups according to their disease severity levels. Field measurements revealed that plant height ranged from 28.0 to 39.7 cm, first pod height from 10.2 to 19.6 cm, and 1000-seed weight from 53.4 to 62.1 g. Due to the disease, flowering duration shortened, the transition to the generative phase accelerated, and reductions occurred in branch and pod numbers as well as total weight. The cultivars 'Yusufhan,' 'Işık,' 'Şahan,' and 'Bozok' stood out with both lower disease severity and reduced yield loss. In conclusion, morphological, molecular, and pathogenic data provide a fundamental source of information for both pathogen identification and determination of resistant green lentil cultivars.