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Weed Scientist Works To Identify "Mystery Weed"
A Canadian weed scientist has been working diligently to identify a "mystery weed" discovered last summer in canola fields southeast of Winnipeg.
  Gary Martens of the University of Manitoba received calls about the purple weed mostly from southern Manitoba but also from as far away as Alberta. Farmers were worried that the tough-to-kill new weed might spread rapidly.
  The weed has some characteristics of wild mustard and some of canola, which made identification difficult.
  "By comparing chromosome counts, we've determined it's a species of wild mustard," Martens told FARM SHOW. "It has nine pair of chromosomes, which indicates it's wild mustard and not a species of canola. It also appears to be resistant to some herbicides."
  Here are some of the characteristics that contributed to solving the riddle of the "mystery weed".
  It has some hairs on its stem but not as many as wild mustard. It stands upright, like hairless-stemmed canola, and does not have the wide spreading branches of wild mustard.
  Unlike canola, which sometimes gets a purple "suntan" on its south side, the weed is purple on both sides. With pods smaller than canola, its seeds look more like wild mustard.
  The weeds appear to have come from fields where canola is grown continuously and where farmers use the same herbicide continuously, he says.
  It does not appear to be affected by common herbicides used to kill wild mustard in canola, such as DuPont's Muster.
  Because of that, Martens recommends using an integrated approach to controlling the weed.
  "Rely less on herbicides and more on cultural practices," he says. "For example, use a heavier seeding rate than you normally do. In the case of wheat, which you might seed at less than 2 bu. per acre normally, use approximately 3 bu. per acre in areas with adequate moisture.
  "Make sure fertilizer is placed so that it feeds the crop rather than the weeds. In other words, band fertilizers at seeding whenever and wherever possible.
  "Always start with clean seed and pick a variety that's competitive. Plant a taller variety rather than a semi-dwarf variety wheat, for example.
  "Tank mix herbicides such as 2,4-D, MCPA or dicamba.
  "If possible, collect chaff at harvest time and feed it."
  Contact: FARM SHOW Followup, Gary Martens, Room 222, Agricultural Building, University of Manitoba, Winnipeg, Canada R3T 2N2 (ph 204 474-8227; fax 7528).

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1999 - Volume #23, Issue #2