I learned many things at Crop Production Week, but the thing that slapped me in the head was how widespread herbicide resistant weeds are becoming.
It started with Eric Johnson’s cautionary tale about Palmer amaranth, which has been described by some American agrologists as the perfect weed. Of course, that does not mean it’s an attractive, short and easy to eradicate weed. Instead, it means it’s a horrible, resistant, seed-filled and enormous beast.
Johnson, an Agriculture Canada researcher who spoke at the Sask-atchewan Soil Conservation Association’s conference last week, provided advice on glyphosate resistant weeds creeping onto the western Canadian landscape. Kochia was his main focus.
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Glyphosate resistant kochia appeared first in Kansas about five years ago, and was discovered in Alberta in 2011. Today, there are several suspected populations in southern Alberta and Saskatchewan.
Glyphosate resistant kochia is bad, but wait until you take a gander at this amaranth horror. The plants are enormous, looming over crops. They come in male and female varieties (very fertile) and you can’t kill them, at least so far.
Glyphosate resistant Palmer amaranth started in southern U.S. cotton crops several years ago and quickly became a nightmare. It spread to Wisconsin, Illinois, Missouri, Kansas, Nebraska, Ohio and southern Michigan, and as of late last week, it looks like it has also arrived in Iowa.
Johnson said — get this — hand weeding amaranth is the only solution in some southern cotton fields. Can you imagine trying that with kochia? And kochia is not as big as amaranth.
Amaranth would likely not survive up here. It loves hot weather as well as nitrogen and lots of water, which unfortunately is stuff that cotton plants are also pretty interested in. But it is moving north.
However, waterhemp, a cousin of amaranth, seems to have seeped into Manitoba on the floodwaters coming in from the northern United States. There’s a nasty surprise.
Western Canadian farmers still have options to battle the glyphosate resistant weeds emerging here, although Johnson warned there are no new chemicals in the pipeline. In other words, what you have is, well, what you have. Tank mix, include dicamba and attack that kochia. If you see waterhemp, kill it now. Southern cotton farmers don’t have those options, and they are paying for it.
