Isolation and identification of a bacterial blotch organism from watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai).

Abstract

A study was carried out on the fruit rot of watermelon (Citrullus lanatus (Thunb.) Matsum. Nakai) in Ilorin, Nigeria between February and May, 2008. A large area planted to watermelon in Obbo-ille, a town near Ilorin, Kwara State was severely infected with both leaf and fruit blotches. Both diseases occurred together in all infected watermelon stands. Leaf and fruit samples were taken to the laboratory at the University of Ilorin, for investigation. A bacterial isolate identified asPseudomonas pseudoalcaligenes Stanier (= Acidovorax avenae) was recovered from both infected leaf and fruit samples. Koch’s postulates were performed on both samples using a suspension of the culture isolate. Symptoms were produced on artificially inoculated leaves and fruits and P. pseudoalcaligenes was also re-isolated. This organism was, therefore, identified as the causal organism of bacterial fruit and leaf blotch in watermelon in Ilorin, Kwara State of Nigeria.   Key words: Watermelon, fruit, leaf, blotch, Pseudomonas sp.