Abstract
A leaf spot bacterium was isolated from diseased leaves of Kaki pigeon pea (Cajanus cajan). The lesions were minute, necrotic and surrounded by a yellow halo, eventually coalescing to form larger area approximately 1 to 2 mm. in diameter. The bacterium is a Gram-negative bacillus, motile, forming butter-yellow, mucoid, and shiny colonies. The bacterium hydrolyzes gelatine, starch, fats, casein, and esculin. It also acidifies glucose, sucrose, and maltose but not salicin, and uses citrate and malonate. When artificially inoculated on healthy pigeon pea, bean (Phaseolus vulgaris) and pea (Pisum sativum), the characteristic lesions were reproduced in their original host only. On the basis of its biochemical characteristics and confirmation by recovery from artificially inoculated diseased pigeon pea leaves, the organism was identified as Xanthomonas campestris pv. cajani. This is the first record of the disease in Puerto Rico.