Ação de produtos químicos in vitro e in vivo sobre Clavibacter michiganensis subsp. Michiganensis, agente causal do cancro bacteriano do tomateiro

Abstract

An experiment was carried out to evaluate the in vivo and in vitro sensibility of a Clavibacter michiganensis subsp. michiganensis isolate (Cmm) to the products kasugamicyn cloridrate, fulusulfamide and oxytetracicline. In the in vitro tests, the inhibition formed around the discs of filter papers soaked with the chemicals was evaluated, for concentrations of 0, 1, 10, 100 and 1000 mg mL-1, 24 h after the installation of the experiment. In the in vivo evaluation, two experiments were installed under greenhouse conditions, with tomato plants cv. Ângela Hiper and two methods of inoculation: leaf spray and stem injury. In both experiments, the plants were sprayed with 0.06 mL L-1 of kasugamicyn chloridrate, 0.025, 0.05 and 0.075 mL L-1 of fulusulfamide and 0.40 g L-1 of oxytetracycline, twice before and twice after the inoculations, at intervals of 5 to 7 days. The incidence of diseased leaves (inoculation by leaf spray) and the severity of the symptoms in the plants inoculated by stem injury was evaluated. The Cmm isolate was in vitro sensitive to kasugamicyn chloridrate, fulusulfamide and oxytetracycline in the respective concentrations of 1000, 100 and 10 mg mL-1. Only the oxytetracycline promoted a lower incidence of diseased leaves in the plants inoculated by leaf spray. None of the chemicals had success in the disease control (inoculation by stem injury). The fulusulfamide, in all concentrations, was toxic to the leaves of tomato plants.