The role of cymoxanil and famoxadone in the management of bacterial spot on tomato and pepper and bacterial leaf spot on lettuce

Abstract Cymoxanil and famoxadone, the components of Tanos 50DF ® (25% a.i. of each product, E.I. du Pont de Nemours and Company, Wilmington, DE) were evaluated alone, together, and in combination with copper hydroxide and/or mancozeb for the control of bacterial spot on tomato and pepper, and bacterial leaf spot on lettuce. Neither Tanos nor its components alone had in vitro inhibitory activity against the copper-insensitive and copper-sensitive species of Xanthomonas evaluated. However, there was a synergistic interaction between copper hydroxide and Tanos in reducing the growth of a copper-resistant strain of Xanthomonas perforans . It appears that both components of Tanos are required for synergism since the addition of only cymoxanil or famoxadone to copper hydroxide did not induce significant reduction of bacterial populations in comparison to copper hydroxide alone. Increased disease control was not obtained on plants in greenhouse trials. In most of the greenhouse trials, the mixture of copper hydroxide and mancozeb combined with Tanos tended to induce similar level of disease control in comparison to different mixtures containing copper hydroxide, cymoxanil and famoxadone indicating that mancozeb might not be necessary in the management of copper-tolerant strains of Xanthomonads.