The use of dye markers as a potential method of reducing pesticide use

Abstract

Colorants used as dye markers may allow better targeting of pesticide sprays and could offer the potential to reduce environmental pollution and overall levels of synthetic pesticide use. A series of experiments was set up to investigate the visibility of commercially available marker dyes, and also those derived from colorants developed for other industrial and scientific uses. Poor visibility and safety concerns with the other products led to effort being concentrated on the food dyes Acid Blue 9 and Acid Red 73. Both dyes gave good visibility on a variety of site types, being clearly visible when wet and dry, but fading within 21 days. However, experiments suggested that if relatively resistant weeds were treated, or low rates of some herbicides were used, dyes mixed with pesticides could reduce efficacy. The addition of 2 l ha-1 Acid Blue 9 (i.e. Dysol Turquoise at 2 per cent of final spray volume) as a marker dye may offer one immediate way of achieving better targeting, and hence some reduction in overall levels of pesticide use in UK forestry.