First Report of Die-back Disease of Onion (Allium cepa L.) Induced by Fusarium equiseti (Mart) Sacc in Nigeria

Abstract

In October 2015 and 2016, onion plants of Barke Aliero exhibiting characteristic symptoms of dried leaves beginning from the tip, abnormal protrusion, root discoloration and curling of the stalk from tip was observed in Kebbi State, Nigeria. In both cases, disease was very severe on seedlings, and disease incidence was 50% or more in most farmer’s fields. Diseased tissue was cut from advancing margin after sterilization and placed in agar plates. The Fusarium sp. isolated routinely from diseased tissue was identified at International Mycological Institute (IMI) Egham, London as Fusarium equiseti (Mart).Microscopic examinations showed the presence of septate (5-7) marcroconidia with tapered apical shape and aseptate microconidia. Pathogenicity test using Fusarium equiseti (IMI No. 604243) isolated from the roots and leaves of diseased plants showed typical symptoms. Three inoculation methods used confirmed multiple soil borne inoculum transmission after the Koch postulate.