Prototype Variable Rate Sprayer for Spot-Application of Agrochemicals in Wild Blueberry

Abstract

Abstract. Wild blueberry growers apply herbicides uniformly to control weeds within fields. The repeated and excessive use of herbicides in bare spots and blueberry plant areas that exist within fields has resulted in an increased cost of production and environmental contamination. A prototype variable rate (VR) sprayer was developed for spot-application (SA) of herbicides to the weeds. The boom was divided into 16 sections (0.76 m per section). The VR control system consisted of eight digital color cameras mounted on a separate boom in front of the tractor, a 20-channel MidTech Legacy 6000 controller, and two 8-channel VR controllers (VRCs) interfaced to a Pocket PC (PPC) via wireless Bluetooth®. Cameras were connected via USB cables to a computer. The cameras were capable of taking the images in real-time. Custom software was developed for processing the images to detect weeds in real-time. The triggering signals were sent to the VRC to open the specific nozzles where the weeds had been detected. The VR sprayer performed well and adequately sprayed propyzamide on red sorrel (Rumex acetosella L.) and flumioxazin on moss (Polytrichum commune) within the selected wild blueberry fields. Results of T-test from experiment 1 suggested that the percent area coverage of water sensitive papers in target and non-target areas after the flumioxazin application was significant indicating SA technique using VR sprayer accurately applied the flumioxazin on targets. SA from experiment 2 resulted in a 69% reduction in propyzamide use with 25 cm before and after target buffer and 28% cover of red sorrel.