Adjuvantes e assistência de ar em pulverizador de barras sobre a deposição da calda e controle de phakopsora pachyrhizi (sydow & sydow)

Abstract

To improve the spray coverage and reduce the productivity losses of soybean crop, this study aimed to evaluate the effect of adding adjuvants to the spray solution combined with or without air assistance on spray deposition, Phakopsora pachyrhizi H. Sydow & P. Sydow control, production losses (weight of 1000 grains) and soybean crop productivity (kg ha-1). Two experiments were conducted in the field with soybean crop, Conquista variety (season 2008/09). One of them was conducted in randomized block design with three doses of adjuvants associated with one cupric tracer. These treatments were also combined at two levels of air assistance on spray boom (0 and 29 km h-1), totaling 6 treatments and 4 replicates. Another experiment was carried out in the same place of the previous experiment in a randomized block design with 7 treatments: fungicide and two adjuvants in mixture with the fungicide, combined with two levels of air assistance on spray boom (0 to 29 km h-1), plus control, and 4 replicates. After spraying of the fungicide pyraclostrobin + epoxiconazole using different technologies, the soybean rust severity was evaluated by estimating the area under the disease progress curve (AUDPC) and soybean crop yield. Air assistance in maximum speed generated by a fan (29 km h-1), combined with the organosilicone adjuvant Silwet L-77 plus fungicide pyraclostrobin + epoxiconazole, contributed to improve soybean rust control increasing the productivity and weight of 1000 grains.