Revista Brasileira De Herbicidas 2011; 10(3): 277-290
Control of Ipomoea nil using tip centrifugal machine of spraying in different volumes of the application with and without adjuvant
The incorporation of tools related to the technology of application of pesticides is inevitable for a sustainable agriculture. We tested the efficiency in the control of Ipomoea nil in initial after-emergency with diuron + hexazinone, in two volumes of application (20 ha-1 and 40 L ha-1), with or without the addition of adjuvant, using peaks of rotating and hydraulically spraying, comparatively. Other two assays had been carried to compare the volumetric distribution of solution and the diameter of the drops produced for the hydraulical and rotating peaks. The percentage of necrosis in the leaves of I. nil plants increased progressively, in two volumes, with or without the use of adjuvants. The rotating peak did not differ from the hydraulically peak how much to the effectiveness. The use of rotary peak decreased coefficient of uniformity (SPAN) in relation to hydraulic peak, indicating the production of drops with greater uniformity. The distribution of the droplets produced by the rotary nozzle provided uneven distribution pattern in relation to the control peak (TT110.01 a 40 L ha-1), due to lower volume of solution used. The peaks spacing was greater with the use of vegetable oil to the volume of 20 L ha-1. The association of the adjuvants to diuron + hexazinone provided to increase the diameter of the drops, with similar efficiency between the two tested volumes. The lower volume of application of diuron + hexazinone (20 L ha-1) in I. nil control can be used, because it provided similar efficacy to the higher volume. The use of adjuvant organ silicone (0.025 % v/v) and vegetable oil (1.0% v/v) may be recommended in the spray system with rotating tip allows for increasing the diameter of the droplets, reducing problems with drift, allowing the use of lower application volume (20 L ha-1), increasing the potential for overlapping droplets on the target.
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