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Weed Sensing Sprayers Show Potential for Use in Eastern Washington Fallow

Posted by Blythe Howell | July 8, 2020

I discuss current research with a weed sensing sprayer in the YouTube video titled, “(09) Lydia Fields: Weed-IT Systems for Chemical Fallow”. Weed sensing sprayers function in real time through detection of differential reflectance, facilitated by near-infrared light. These sprayers are equipped with sensors on the spray boom that emit both red and near-infrared light. Chlorophyll in plants effectively absorbs red light, while reflecting near-infrared light. This creates a ratio that the sprayer uses to differentiate between bare ground, stubble, and plant material.

When a weed sensing sprayer detects a weed in the field, a signal triggers the opening of a solenoid valve at the nozzle. The opening solenoid causes for an increased functional rate of herbicide to be released from the nozzle in a spot spray fashion over the detected weed.

This technology has the potential to improve Eastern Washington fallow weed management in a few major ways:

Economic savings can be improved through use of a weed sensing sprayer in fallow. Spot spraying action effectively reduces the overall amount of herbicide dispensed without sacrificing optimal weed control.

Diversification of herbicide modes of action, and not relying on broadcast applications of glyphosate for weed control, is possible by using weed sensing spray technologies. The economic savings associated with using a weed sensing sprayer will allow farmers to explore the use of different herbicides and hopefully move away from solely using glyphosate. This will also combat the development of glyphosate-resistant weeds in eastern Washington fallow systems.

Improved weed control has been observed in weed sensing sprayer trials when compared to broadcast applications. In specific cases, the increased functional rate applied by the weed sensing sprayer in a ‘spot’ treatment results in improved control of problem weed species. However, this is dependent on both the herbicide used and the weed stage.

You can read about the results from two of last year’s field studies with weed sensing sprayers at the following:

The future of chemical fallow management is exciting! Be on the lookout for more information on weed sensing sprayers from WSU on the Wheat & Small Grains website.


For questions or comments, contact Lydia Fields via email at lydia.fields@wsu.edu.

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