DEVELOPMENT OF A TRIGGER-ON INDICATOR FOR A WEED SENSING SPRAY UNIT

Authors: Siemens, Mark; Hulick, Donald; JEPSEN, BILL - GROWER

Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2007
Publication Date: 5/15/2007
Citation: Siemens, M.C., Hulick, D.E., Jepsen, B. 2007. Development of a trigger-on indicator for a weed sensing spray unit. Crop Management. Online Peer Reviewed Journal of Applied Crop Science doi:10.1094/CM-2007-0515-01-BR.

Interpretive Summary: Intermittent spray systems that automatically spray only when weeds are present have been commercially available since 1992 and can significantly reduce herbicide usage by 50-90% as compared to broadcast applications. The Weedseeker® (NTech Industries, Ukiah, Calif.) is one such system that traditionally has been used to spot spray weeds in orchards and along road sides, but has seen increased adoption for use in controlling weeds on large acreage cereal grain farms. A major drawback with the design for use on the wide boom, multi sensor unit sprayers commonly used on these farms is that it is difficult for the user to see when one of the spray units is actively spraying. This is problematic since each sensing unit is calibrated independently and if one of the sensing units is calibrated when the sensor is over a weed, the unit will not detect weeds of similar size or smaller when spraying. To overcome this problem, a simple, low cost trigger-on indicating device was developed to provide the operator with visual feedback. The design is an electronic circuit that detects when the Weedseeker® unit is spraying and then activates a super bright LED that can be seen from the operator's cab. The performance of the device was evaluated in 2006 on a 3,000 acre commercial farm near Heppner, Oregon. The units performed reliably over the 150 hour use period and were well received by the operator. The indicator lights were readily visible by the operator, even during intense daylight. The design requires no modification to the Weedseeker® unit and can be built for $18.23 each. A circuit diagram and parts list is provided so that operators interested in this technology can make the device. This device will help increase the adoption of herbicide use reducing intermittent spray systems on large acreage farms.

Technical Abstract: Although the Weedseeker® (NTech Industries, Ukiah, Calif.) spray system that automatically sprays only when weeds are present has been commercially available since 1992, a major drawback with the design is that it doesn't provide any feedback to the user when one of the spray units is actively spraying. This is problematic, particularly on wide boom, multi sensor unit sprayers since each sensing unit is calibrated independently and if one of the sensing units is calibrated when the sensor is over a weed, the unit will not detect weeds of similar size or smaller when spraying. To overcome this problem, a simple, low cost trigger-on indicating device was developed and field tested. The design centers around the small, LED light provided on the rear of the Weedseeker® sensor unit that turns on when the spray solenoid valve is activated. The device developed utilizes this light source to activate a phototransistor which in turn activates a super bright LED that can be pointed toward the operator's cab. The performance of the device was evaluated by installing 40 units on a spray boom and then operating the sprayer to control weeds on 3000 acres of commercial farmland near Heppner, Oregon, during 2006. The units performed reliably over the 150 hour use period and were well received by the operator. The indicator lights were readily visible by the operator, even during intense daylight. The design requires no modification to the Weedseeker® unit and can be built for $18.23 each. A circuit diagram and parts list is provided so that operators interested in this technology can make the device.