What’s New in the World of Weed Control?
By Keana Boere, Intern Extension Agrologist, Tisdale
Herbicide-resistant weeds are increasing the pressure for new weed control options. Below are several new innovations in weed control, some of which are still being developed while others are commercially available.
Physical impact mill attachments on combines provide harvest weed seed control. Commercially available models include the Integrated Harrington Seed Destructor, Seed Terminator and the Saskatchewan-produced Redekop Seed Control Unit. Impact mills work by crushing and destroying weed seeds before they exit the combine with chaff and residues. This destruction prevents the seeds from germinating, eliminating them before they become weeds. One limitation with impact mills is that weed seeds need to be retained on the plant until crop harvest so they pass through the impact mill. The impact mill is over 95 per cent effective at destroying weed seeds that enter it.
The X-Steam-inator is a non-selective form of weed control that kills weeds using high temperature steam generated from electricity. This technology is still being evaluated for large-scale field operations, and commercial scale prototypes are currently not available.
Autonomous weeding robots use sensors, cameras, and GPS to move through fields day or night, with no human operation. Lasers, small sprays of herbicide or small spinning blades are used to control weed seedlings. Sensors identify weeds from crops using leaf shapes or leaf reflectance; some can pull GPS data of seeding history to determine if a crop was planted in that exact location or if a weed has emerged. Large-scale use of these robots is still in development stages, but models are available for low-acreage, high-value cropping systems, like vegetable production.
Precision spraying technologies, like Weed-it, increase the efficiency of herbicide applications by only applying herbicide to detected weeds in a field. This reduces the amount of herbicide being used and allows for a more economical application of a diverse herbicide mix. While it could be argued that this technology on its own may only serve to delay herbicide resistance, used in combination with other weed control options it creates another tool in the toolbox. Precision spraying technologies are commercially available with different application modes including spot spray, dual spray and full coverage.
Biological weed control methods have been successfully used for years. Well-known examples involve using natural enemy insects for control of invasive weed species. Biopesticides are also being developed using natural weed pathogens and phytotoxins. Bioherbicides, biofungicides and bioinsecticides are all being investigated. These products could lead to new modes of action or herbicide selectivity to help with herbicide resistance problems.
RNA Interference technology uses RNA to silence key weed genes. Weeds will either die or become more susceptible to herbicides and other control methods when exposed to RNA. Very specific RNA sequences are used, so specific weed species can be targeted. Traits will need to be developed for a wide variety of weeds to control different species. This idea is still very much in its infancy but will likely be developed into a spray.
More technologies are being researched involving drones and genetic engineering, but their economic feasibility and efficacy varies, so an integrated weed control plan will still be required. There is potential, however, for more integrated control options to become available to producers in the future.
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