Efficeincy of antagonistic microorganisms on control of bacterial wilt of tomato

Abstract

Antagonists, Streptomyces-15 and Trichoderma harzianum were selected from laboratory test on inhibition of Ralstonia solanacearum, the causal agent of bacterial wilt of tomato. The two antagonists were then evaluated for control of the disease in greenhouse. In each potted soil planted to tomato were inoculated with R. solanacearum at concentration of 2 x 108 cfu/ml at 5 cc/pot and with or without 3,000 eggs of root-knot nematode (Meloidogyne incognita) per pot. Treatments of antagonists, single or combined, composed of Streptomyces-15 cultured in peat moss and T. harzianum cultured in steamed sorghum grain substrate, each amended at the rate of 10 g/pot. The fungicide copper oxychloride was also used as a compared treatment. After 4 weeks, the results showed that T. harzianum gave better control of the disease than Streptomyces did. Combined treatment of the two antagonists produced greater disease control effect than single one. However, The presence of nematode reduced the efficiency of the antagonists. Copper oxychloride could not reduce wilting incidence of tomato. Treatments of the antagonists showed no effect on fresh shoot weight of tomato at 4 weeks.