ABSTRACT Guava wilt is a destructive disease threatening guava cultivation in India, with complex aetiology and high economic implications. The disease is widely prevalent in major guava‐growing regions of Punjab and poses a significant threat to orchard productivity because of its progressive nature and difficulty in management. The present study aimed to elucidate the diversity of Fusarium species associated with guava wilt in Punjab. Surveys conducted during 2021–2024 recorded characteristic wilt symptoms, including leaf yellowing, drooping, twig drying and death of trees in severe cases. A total of 76 Fusarium isolates were obtained from diseased plants and characterised based on cultural and morphological traits. Considerable variability was observed in colony colour, mycelial growth, sporulation rate and spore dimensions. Pathogenicity assays on guava seedlings confirmed all isolates to be pathogenic, with disease severity ranging from 6% to 67%. Molecular identification using rDNA internal transcribed spacer (ITS), transcription elongation factor ( tef‐1α ) and RNA polymerase 2 ( rpb2 ) regions produced fragments of 502, about 580 and 980 bp, respectively. Sequence analysis of 12 representative isolates revealed the presence of three species of Fusarium associated with wilt, namely F. falciforme (seven isolates), F. solani (four isolates) and F. oxysporum f. sp. psidii (one isolate). Phylogenetic analysis confirmed their taxonomic placement. This study provides the first comprehensive evidence of coexistence of multiple Fusarium species contributing to guava wilt in Punjab, highlighting the need for integrating morphological and molecular tools for accurate pathogen diagnosis and the development of integrated disease management strategies against this devastating disease.
Negi et al. (Sun,) studied this question.