Abstract

Ten different equipments were tested and the fluorescent tracer method was used for determination of deposited spray drift. Measurements were carried out both in the field and in laboratory studies where three wind velocities, 1.0, 2.5 and 4.0 m/s were used at different working pressures. In the field artificial collectors (filterpapers) were placed at 2.5, 5.0, 10.0, 15.0 and 20.0 m downwind and parallel to the driving direction. A wind tunnel was utilized in the laboratory studies and measurements took place at 2.5, 5.0, 10.0 and 15.0 m from application point. Droplet size measurements were carried out with the Malvern Particle Sizer for different nozzles and at different pressures. The volume percentage consisting of droplets less than 100 μm was recorded and used as the dependent variable for fitting a linear regression model. By fitting sample values to various curves it was found that either the linear (Y=a+b*X) or the exponential (Y=a*e(b*X) (a>0)) curve would give the best correlation. The differences recorded in spray drift deposits for the equipments tested could mainly be attributed to differences in volume percentage less than 100 μm. One exception was the CDA sprayer (Micromax) which in spite of having the smallest amount of droplets less than 100 μm resulted in relatively high spray drift deposits. It was verified that old recommendations, not to spray in strong winds (more than 3-4 m/s), reduce the pressure and to take relative humidity and temperature in consideration, are still valid. Furthermore it is of outmost importance to choose equipment and nozzle sizes which facilitates spraying with a low volume percentage of droplets less than 100 μm. It is felt that improvement of the hazardous drift situation could fairly easy be implemented. But the devices for measuring temperature, relative humidity and wind velocity must be accessible for every spray operator. Another way or complementory way of reducing winddrift is further development of various kinds of windproof sprayer. The last 5-10 years of research work in spray application has prooved that the biological effect can be improved by reducing the droplet size to achieve higher quality deposits. This will doubtlessly increase drift hazards unless adequate steps are taken. The littereture review revealed that contamination of the spray operator mainly occures during: - handling of concentrated pesticides - cleaning of blocked nozzles - cleaning/emptying of spray tanks and equipment. Further development and/or increased usage of following systems ought to efficiently contribute to the reduction of the mentioned hazards: - Closed filling systems - Dosage equipment for direct injection of the pesticide into the water, close to the nozzles - Self cleaning nozzles

Keywords

vindavdrift; avsättning; sprutor; bekämpningsmedel; exposition; kontamination

Published in

Rapport - Sveriges lantbruksuniversitet, Institutionen för lantbruksteknik
1987,
ISBN: 91-576-3142-5
Publisher: Institutionen för lantbruksteknik, Sveriges lantbruksuniversitet

Permanent link to this page (URI)

https://res.slu.se/id/publ/125645