Comparing Spray Gun and Spray Boom Applications in Two Ivy Crops with Different Crop Densities

Abstract

Flemish greenhouse growers predominantly use handheld spray guns and lances for their crop protection purposes despite the heavy workload and high risk for operator exposure associated with these techniques. These spray application techniques have also shown to be less effective than spray boom equipment under many conditions. Handheld spraying techniques are less expensive, however, and they are more flexible in practical use. Many growers also erroneously believe that high spray volumes and pressures are needed to assure good plant protection. The aim of this work was to evaluate the spray deposition, penetration, and uniformity between a manually pulled horizontal spray boom as compared with a spray gun under controlled laboratory conditions. In this study, we evaluated six spray application techniques, i.e., three spray boom and three spray gun techniques. In general, the deposition results were comparable between the spray boom and the spray gun applications. The spray boom applications, however, resulted in a more uniform spray distribution. At the plant level, the spray distribution was not uniform for any of the techniques used; the highest deposits were observed on the upper (or adaxial) side of the top leaves. Using spray guns at a higher spray pressure did not improve spray penetration in the canopy or deposition on the bottom (or abaxial) side of the leaves. Of the different nozzle types tested on the spray boom, the extended range flat fan XR 8003 gave the best results. Crop density clearly affected crop penetration and deposition on the bottom side of the leaves.