Take a peek into the future of weed control – Aussie style. Imagine, if you will, pulling a cage mill behind your combine that "eats" chaff and seed tailings, then spits them out the back.
That's one of the harvest-time weed seed control concepts studied by researchers at the University of Western Australia. It was recently featured in Weed Technology, a Weed Science Society of America journal.
Yes, the machine – the Harrington Seed Destructor – was developed by a farmer. Ray Harrington, a long-time livestock and crop farmer in Western Australia, designed the trailer-mounted cage mill, with chaff and straw transfer systems. Powered by a diesel engine, the researchers claim it destroys at least 95% of annual ryegrass, wild radish, wild oat, and brome grass seed in the chaff fraction of harvest residues.
The harvest weed control system was studied in 25 large wheat fields over 10 growing seasons. Most of those weed species are attached to upright plants, allowing their harvest.
Up to 80% of annual ryegrass seeds, for instance, are typically cast aside as chaff and redistributed over the field. While that may be good as a cover crop, it may not be for other cereal grains or soybeans. Keep in mind that these weed seeds have a relatively short survival life in the seedbank.
Removing most of the weed seed lessens the risk of developing herbicide resistance – already a widespread problem "Down Under", particularly with ryegrass and wild radish. The researchers emphasize an integrated approach, teaming up harvest control with early-season herbicide control.
Only fields using that one-two punch reached the targeted low-weed density goal.
Harrington's Destructor was compared with three other harvest weed seed control method. Here's a quick look at them:
•Chaff collection cart: Pulled behind the combine, it collected weed seeds and other plant materials, to be burned or used as livestock feed. They still had to be piled at field-edge with the potential for being redistributed in the fields.
vWindrowed residues: In Western Australia, those windrows are typically burned. That likely wouldn't pass muster in the United States, let alone the Northeast.
vDirect-bale: A baler attached to the harvester creates bales of chaff and straw residue for livestock feed. Even the Australians found a limited market for them. Who wants to buy bales with high weed seed concentrations?