The utilization of graded poly then e bags for meas urement of spray throught put is current practice among technicians and farmers. It s us e is very simple, basically, the liquid sprayed from one nozzle is collected during a period equivalent to run 50 meters. The volume collected is indicated on a scale printed on the bags with gives the spray volume in 1/ ha directly. Free sample of these plastic calibrators are distributed for promotional purpose by the pesticides companies. Five bags of each of 6 different brands were checked. Water at 20°C was filled in to the level of 100 1/ha, 250 1/ha and 400 1/ha. These volumes were meas ured in a standardized measuring cylinder and the actual spray volume calculated. Positive and negative errors of measure ment were found in all graded polithe ne bags. The largest error was 35,2% higher than the indicated mark. Considering these results one can recommend more accuracy in manufacturing such a device. It is also suggested modifications in printing graded scale and operating instructions.
calibration; sprayer; pesticide application