Ultra-targeted spraying could one day give growers more weed control options while sharply cutting herbicide use, according to research summarised by the GROW (Getting Rid of Weeds) network and reported by CropLife. The question matters most for non-GMO corn and soybean growers, who have fewer post-emergence herbicide options than farmers using herbicide-tolerant traits; University of Wisconsin-Madison weed scientist Dr Rodrigo Werle says resistance has already pushed some to rethink their production systems.
The trial used the ARA sprayer from Swiss company Ecorobotix, a camera-guided system that uses artificial intelligence to identify weeds plant by plant and treats only a 2.4-inch-by-2.4-inch area where it detects one. A "safety zone" feature leaves a buffer around crop plants and holds fire when a weed is too close.
That buffer led researchers to test whether such precision could allow a non-selective herbicide such as glufosinate to be used in conventional row crops without unacceptable damage. Current labels and regulations do not permit this, so the work was a research trial of the concept only.
The results depended heavily on a strong base of residual herbicides: fields with robust pre-emergence programmes did better whatever post-emergence strategy followed, because targeted spraying then only had to deal with the few weeds that escaped. Combined with stronger pre-emergence programmes, precision application saved 64% to 83% of post-emergence herbicide. Ragweeds, velvetleaf and grass weeds were controlled, and crop injury stayed minimal regardless of herbicide or sprayer setting.
Weeds growing right inside the crop row were deliberately left untreated to protect the crop, a reminder that integrated weed management is still needed. Researchers caution that wider adoption depends on regulatory change and more field validation, but say targeted systems could help growers preserve existing herbicides and use less of them.
Photo: Amada44 / Wikimedia Commons (CC BY 3.0)
Source: CropLife
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