Control of Alternaria solani and Xanthomonas vesicatoria in tomato by Pycnoporus sanguineus formulated extract

Resumo

The continuous use of pesticides protecting plants against diseases can result in several damages due the environmental pollution and food residues. Thus, it is necessary the search for new plant diseases control technologies. The objective of this study was to evaluate the in vitro antimicrobial activity against Alternaria solani and Xanthomonas vesicatoria and the control of early blight and bacterial spot on tomato plants, using stable formulation, as soluble powder, from Pycnoporus sanguineus. To determine the shelf life, the soluble powder was kept at 40 ºC during 0, 60, 120 and 180 days and assayed with five concentrations (0, 50, 100, 150 and 200 mg L^-1). When the shelf life and the best concentrations were defined, it was evaluated the time-interval of spraying of seven, 14 and 21 days. As control treatments were used the fungicides azoxystrobin (200 mg of active ingredient – a.i mL^-1) to early blight and oxychloride (400 mg a.i. mL^-1) to bacterial spot. There were no in vitro antifungal and antibacterial activities from extracts. The calculated concentration of P. sanguineus extract for the best control of diseases was 130 mg L^-1, with 24 months of shelf live to soluble powder. In vivo, the P. sanguineus extract gave the same control of fungicides to early blight and bacterial spot, with values up to 79.31% of disease reduction, with spraying at seven days. These results show that the aqueous extract obtained from P. sanguineus soluble powder formulation, can protect tomato plants against early blight and bacterial spot, probably by resistance induction.