Morpho-Molecular Identification of Fusarium equiseti and Fusarium oxysporum Associated with Symptomatic Wilting of Potato from Pakistan

Potato (<i>Solanum tuberosum</i> L.) is one of the emerging staple crops in Pakistan, with Punjab producing over 95% of the country's potatoes. Wilt is an emerging threat to the potato crop worldwide, including in Pakistan. We identified and characterized <i>Fusarium</i> species associated with potato wilt in Pakistan through morphological and molecular analyses. Samples were collected during the 2020-2022 potato seasons from five major potato-growing regions: Sahiwal, Chichawatni, Pakpattan, Kamalia, and Faisalabad. Morphological characterization, <i>internal transcribed spacer</i> (<i>ITS</i>) sequencing, specific <i>translation elongation factor 1-alpha</i> (<i>TEF</i>) sequencing, and phylogenetic analysis were used to identify six different <i>Fusarium</i> species: <i>F. oxysporum</i>, <i>F. equiseti</i>, <i>F. incarnatum</i>, <i>F. fujikuroi</i>, <i>F. annulatum</i> and <i>F. thapsinum</i>. Pathogenicity tests in a greenhouse revealed that <i>F. oxysporum</i> and <i>F. equiseti</i> were responsible for Fusarium wilt in all sampled regions, with <i>F. oxysporum</i> being more prevalent in wilted samples. This is the first report of <i>F. equiseti</i> on wilted potatoes in Pakistan. In vitro biocontrol tests using <i>Trichoderma harzianum</i> showed 89% inhibition against <i>F. equiseti</i> and 65% inhibition against <i>F. oxysporum</i>. These findings on <i>F. equiseti</i> will aid in developing future control strategies, including biocontrol measures for Fusarium wilt in potatoes.