A new bacterial disease of tomato in Viçosa, Minas Gerais state

Abstract

In 1991 it was observed a new disease of tomato in commercial plantations at the region of Viçosa, Minas Gerais State, Brazil. The disease shows up as necrotic lesions in leaves, either irregularly round or along leaf borders, initially small and increasing in size with age. These lesions are usually surrounded by a chlorotic halo. Drop exsudate tests indicated a bacterial etiology for the disease. From such lesions, it was consistently isolated a bacterium that gives rise to clear, opaque, regular, elevated and shinning colonies. Inoculations tests rendered HR in leaves of coffee, tobacco, bean and passion fruit as well as typical disease symptoms in tomato leaves. The bacterium is a single, regular, straight, Gram-negative, strictly aerobic rod, unable to use asparagine as sole C and N source, unable to produ-ce xanthomonadins, does not induce hipertrOphic growth in the host, produces a blue fluorescent pigment, grows easily in routine culture media and was positioned in the genus Pseudomonas, fluorescent group. Biochemical, staining and biological tests indicate the pathogen belongs to the species Pseudomonas syríngae pv. tomato,