End of Project ReportTrials 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
