The use of air induction nozzles for herbicide application to sugar beet.

Abstract

Trials were carried out over a three-year period in Oak Park to compare airinduction with conventional nozzles for weed control in sugar beet. Two makes of low-drift nozzle (Bubble Jet and DriftBETA) were compared with conventional fans. All nozzles were used at a pressure of 3 bar. Two sizes (015 and 03) of each type of nozzle were used, to allow volumes of 110 and 220 litres per hectare to be applied. These nozzles were used to apply two-spray programmes to sugar-beet crops. In four of the weed control trials, tank mixes of products with some residual action (Progress, Goltix, Venzar and Debut) were used. In the other two trials, a contact-only spray (Betanal E) was used. The aim was to see how the nozzles behaved with contact-only sprays as well as those with more complex modes of action. Spray drift was also measured with the size 03 nozzles. Spray drift reductions from 37% to 64% were measured when the air-induction nozzles were compared with conventional fans. In general, the tank mix programme gave better weed control than the contact-only treatments. Within programmes, differences between the application methods were significant in two trials. In both of these, the conventional nozzles gave the best results. Looking at the mean results of the tank-mix trials, two trends were suggested: higher water volumes gave slightly better weed control, and the effect of the coarser sprays was slight. With the contact-only sprays, the decline in performance with the coarser sprays was more emphatic, and the lower volumes appeared to give slightly better control. It is concluded that in calm conditions conventional fan or cone nozzles should continue to be used, but that air-induction nozzles are a valuable fall-back when it is necessary to spray in a moderate breeze. In these situations, and with the normal tank-mix programmes, small nozzle sizes applying very low volumes should be avoided. Makes of air-induction nozzle which give very coarse spray should also be avoided.