Measurement of spray drift with hand held orchard spray applications

As part of the series of studies being carried out within the current EU fu nded project SMT4-CT96-2048, field trials were performed to measure the pot ential for applicator and bystander exposure from pesticide applications to tree crops. The study was done in the Algarve region of Portugal, with the collaboration of the regional agricultural service, with a mature orange c rop, height 3.5 m and planting distance 2.65 x 7.0 m. The applications were made with a hand held lance with an adjustable nozzle and an intended appl ication rate of 1000 1/ha This technique is still one of the pesticide appl ication methods employed in the region. The tracer Sunset Yellow was used a t a concentration of approximately 2 g/l, to apply to a total area of 650 m (2) (35 trees) for each trial area. Spray drift was collected on vertical a ir liness and also filter paper placed on the ground, to measure both airbo rne drift and drift fallout, using methods based on the ISO draft protocol. The data indicate that on average, 6.2 Vha was being deposited on the grou nd at a distance of 10 m downwind of the treated area. The proportion of th e applied volume still airborne at 10 m downwind was 0.33 to 2.05 %, and at 20 m 0.1 to 0.56 %. Both deposited and airborne spray drift data can be us ed to extrapolate to potential bystander exposure.