Geographical distribution, morphology, and phylogenetic analysis of Fusarium proliferatum, the causal agent of olive wilt in Pothohar, Pakistan

A disease survey of olive (Olea europaea) orchards was conducted across the Pothohar region, covering 32 locations in the Attock, Chakwal, Jhelum, and Rawalpindi districts. Disease incidence was recorded at five locations in Chakwal and Rawalpindi during 2020 and 2021. Pathogenic fungal isolates were analyzed for morphological characteristics, with spore dimensions ranging from 2.89 µm to 14.03 µm and colony pigmentation varying from white and pink to indigo and pink-indigo. The Fusarium proliferatum isolates were tested for pathogenicity against olive, eliciting disease severity ranging from mild to severe, with no significant differences observed within each virulence group. Molecular analyses of the isolates, including PCR amplification of the ITS region, Sanger sequencing, and phylogenetic analysis, confirmed their identity as F. proliferatum. These isolates exhibited the closest genetic relationship to those from Glycine max (soybean), Triticum aestivum (wheat), and Panax ginseng (ginseng). These findings highlight the growing threat of Fusarium wilt to olive production in Pakistan and emphasize the need for targeted disease management strategies to mitigate its impact on the local olive industry. This study represents the first report of F. proliferatum causing olive wilt in Pakistan.