A direct chemical application end effector was developed to directly apply chemical via a weed's vascular tissue by cutting the weed's stem and wiping chemical on to its cut surface. The end effector consists of two micro-pumps, a custom-designed circular saw with a DC motor, an applicator, a chemical tank, a flow controller, and a micro reservoir. The field robot, equipped with a computer and a 5-degree of freedom arm, controls the movement of the direct chemical application end effector. A direct chemical application end effector was tested to quantify the application dose and to examine the potential for controlling weeds. The average application dose of the end effector ranged from 21.89 mg to 56.18 mg per target, with a coefficient of variation (CV) range of 33.79-60.85%. Using the direct chemical application end effector, chemical was applied to two species of weeds, yellow foxtail (Setaria glauca) plants and velvetleaf plants (Abutilon theophrasti) as representative grass and broadleaf weeds, respectively. The majority of the weeds (90.9%) treated by the end effector showed symptoms of chemical application on the sixth day and was dead ten days after application although the end effector used only 22% of active ingredient of a broadcast application. The developed end effector may provide a solution to reduce chemical use in field application, to increase herbicide efficacy, and to limit the herbicide contamination in the environment by directly applying a minute amount of herbicide only to weeds. Published by Elsevier Ltd on behalf of IAgrE.
