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Banana Xanthomonas wilt is primarily spread by lance flies in the genus Silba through banana inflorescence in Ethiopia

Birtukan Getahun: Wolaita Sodo University

<div><span>Banana <em>Xanthomonas</em> wilt (BXW) caused by <em>Xanthomonas</em> <em>campestris</em> pv. <em>musacearum</em> (Xcm) is an important disease of banana. Insects feeding on wounds resulted from abscission of infected flower and/or bract can possibly transmit the bacterium to healthy plants. This study was conducted to identify insect vectors and floral morphologies attributed to inflorescence infection on banana plants. Insects were collected and identified by genus from flowers of Pisang awak ‘Abesha muz’ and Cavendish genotypes in fields across southern Ethiopia in 2016. The presence of Xcm on insects was determined by isolating bacterial colonies in semi-selective media. Infectivity tests were conducted by inoculating Xcm suspensions on flowers and pseudostems of 30 plants of each genotype in field and green-house, respectively. Lance flies in the genus <em>Silba</em> were frequently associated with Xcm feeding on wounds from which the male flower and bract had abscised. Inoculation of these sites with Xcm produced infection on Pisang awak and ‘Abesha muz’. Cavendish plants with persistent bracts and flowers apparently, however, remained healthy. When inoculated at the pseudostems of plantlets, BXW was produced regardless of banana genotypes. Manifestation of the first symptom through inflorescence inoculation took 40 days, exceeding by far the 60 days record on plantlets inoculated on pseudostems. This study demonstrated that the spread of BXW primarily occurred through the male flower wounds by insects.</span></div>