SPRAYING 101 | OPTICAL SPOT SPRAYING MAKES SENSE
Optical Spot Spraying Makes Sense Tom Wolf, PhD, P.Ag. Tom Wolf grew up on a grain farm in southern Manitoba. He obtained his BSA and M.Sc. (Plant Science) at the University of Manitoba and his PhD (Agronomy) at Ohio State University. Tom was a research scientist with Agriculture & Agri-Food Canada for 17 years before forming AgriMetrix, an agricultural research company that he now operates in Saskatoon. He specializes in spray drift, pesticide efficacy, and sprayer tank cleanout, and conducts research and training on these topics throughout Canada. Tom sits on the Board of the Saskatchewan Soil Conservation Association, is an active member of the American Society of Agricultural and Biological Engineers and is a member and past president of the Canadian Weed Science Society.
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Site-specific treatments have long been a goal in agriculture. It makes sense to provide inputs or treatment at rates that reflect the local situation. To a large degree, those capabilities have been available for fertility and seed inputs for some time, with input zones reflecting soil types or topography. But the sprayer world has not seen as much site-specific treatment. The reasons: pest maps are time-consuming to generate and their usefulness may be short-lived; weeds are fairly ubiquitous, and it usually makes sense to treat an entire field; and sprays are relatively inexpensive compared to fertilizer or seed. When it comes to spraying, we need to redefine site-specific. While traditional zone maps (corresponding to, say soil type and/or elevation or slope position) allow unique treatments on a scale of acres, new sensors have allowed sprayers to basically leapfrog this approach and treat each square foot uniquely. These sensors identify plants directly and create an immediate treatment response. The idea, and technology, has been around agriculture since the early 1990s, with Concord DetectSpray and later Trimble WeedSeeker. For various reasons, these never became widespread. New cutting-edge technologies are about to change this. WEEDit is an optical spot spraying (OSS) system manufactured in the Netherlands by Rometron (https://www.weed-it.com/), and has been available on the market for several years. It is widely adopted for use in Australia and South America, is now making inroads in North America. WEEDit spray booms contain sensors placed at one-metre intervals. These scan the ground