Abstract
A new bacterial disease characterized by spots on the leaf, petiole, flower and peduncle of the florists'' geranium (P. .times. hortorum) was incited by Pseudomonas cichorii. An isolate from geranium was pathogenic to cabbage (Brassica oleracea var. capitata), cauliflower (B. oleracea), chrysanthemum (Chrysanthemum morifolium), and a weed host, prickly poppy (Argemone mexicana). The causal organism produced a green fluorescent pigment on King''s medium B and was arginine dihydrolase negative and oxidase positive, which identified it as P. cichorii. In greenhouse experiments, cupric hydroxide, cupric hydroxide with S, and basic copper sulfate, when used singly or in combination with mancozeb, were moderately effective in controlling Pseudomonas leaf spot on P. .times. hortorum cultivars Heidi and Ringo plants.

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