Evaluation of motorised knapsack mistblowers for fungicide application in coffee, 1: The Holder Supra 75 mist blower

Holder Supra 75 motorised knapsack sprayer was found to consume 1.8 litres of fuel per hour compared with the manufacturer fuel figure of 568 ml/hr. The revolution per minute (R.P.M.) of the engine was found to be 5500 compared with the manufacturer's figure of 5000 R.P.M. The speed was constant throughout the tests. This is considered as an essential quality for the sprayer in order to maintain uniform rate and droplet spectrum. The original 4 nozzles which had no vortices produced very course spray mists which were found to be less effective in spray penetration and distribution than the mists produced by the two nozzles with vortices. Therefore, the original 4 nozzles without vortices should not be used for fungicide application in coffee. The olumes (610 l/ha and 677 l/ha) emitted by the two nozzles (size 1.2 and 1.5 mm respectively) with vortices gave satisfactory spray application. Good penetration, distribution and even coverage of the sprayed material on all positions of coffeetrees were achieved by placing the tip of the spray hose at one (1) metre from the aimed target. Air speed of 34.4 (km/hr), air volume of 176.2 : 10 exponent 4 (cm3/min) and droplets in size range of (61-58 microns and 103-231) microns which were also measured at the same distance (one metre from the tip of the spray hose), are the mechanical and physical performance of the machine under test, which contributed to this efficient spray application. Therefore, it can be concluded that both mechanically and physically, the sprayer under test in an efficient equipment for fungicide application in coffee