Another pretty weed is giving nightmares to minimum till farmers in Alberta.
White cockle, usually found in pastures and forages, appears to have jumped to cereals and oilseeds planted in fields under minimum tillage.
“I was really surprised when I heard about white cockle being a problem in cereals and oilseeds,” said provincial weed specialist Dan Cole.
He reports that farmers in north-central and northeastern Alberta are having serious problems with the weed.
Bonnyville crop specialist Jay Byer said infestation is particularly bad around Lac La Biche, where some forage seed crops are being rejected because of weed seeds.
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“If you can’t sell that as alfalfa seed, that’s a big loss,” Byer said.
More than half of Alberta’s counties and municipal districts report problems with white cockle, but it is a minor problem in Saskatchewan, where reports are scarce. Manitoba also has relatively few reports of problems with the weed.
White cockle is a biennial. It germinates and produces a rosette in the first year, then overwinters and flowers the following year.
If it’s there you’ll know it, said Cole.
“It’s a very showy weed because it makes the field very white.”
Traditionally the weed has only been a problem for perennial forage growers and pasture keepers because yearly tillage kills white cockle before it can seed.
Cole said the weed tends to appear one year after seeding a forage, especially if a cover crop is used.
The spring after forage seed is planted the crop is small and grows slowly, so the weed can advance and overtake forage plants. It is also seen in forage crops and pastures that are poorly managed, Cole said.
If gaps appear in the forage canopy, white cockle will move in to fill the space.
Byer said local studies suggest white cockle infestations are 10 times worse in minimum-till fields than in traditionally cultivated crops.
Cole added that only one chemical treatment, Target, seems to be effective against white cockle. Others are being tested by researchers and farmers in Bonnyville and Wetaskiwin.
Chemical harmful to crop
But Target kills legumes, so growers have few choices if the weed infests those crops, Cole said.
Plowing the field and re-seeding a perennial forage probably won’t do the trick, because the weed is most aggressive in newly planted forages.
“You may have to live with it until you can squeeze it out,” said Cole.
The plant is not poisonous and has good protein while small, but it tends to reduce yields in infected fields.
And it’s hard to leave alone, Cole said. “It looks awful with that showy white flower.”
Researchers are hopeful a new chemical will offer control for minimum-till farmers so white cockle does not become a lasting headache.
