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Declaring war on waterhemp -even in Ontario

August 28, 2009
By AgWeb/FarmJournal

Aug. 27, 2009 -Waterhemp is becoming a bigger concern for growers in the US Midwest, and is also appearing in fields in Ontario. Of vital importance is to identify this weed, which is resistant to four herbicide classes.


August 27, 2009

Pam Smith

I’m riding shotgun with Aaron Hager, University of Illinois extension weed specialist. We’ve been out weed watching. This generally consists of Hager swerving off the road occasionally to do an inspection of some curious looking weed.

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Today, we pass a perfectly lovely and weed free field of soybeans—except for a small strip of waterhemp near the field entrance. “This weed was run over and missed getting sprayed,” says Hager, as he examines the offenders. “But this one got hit with glyphosate and survived.”

There is official weed “CSI-type” protocol to officially determining if a weed is resistant. Hager can’t say for sure if the weeds are resistant to an herbicide without growing out the seeds from the weeds and exposing them to various herbicide tests in a greenhouse setting. New diagnostic tests are helping speed this process, but they must still done in a lab setting.
However, there are field symptoms in this field to watch for when it comes to detecting weeds that might be resistant to herbicide. Typically resistant infestations start as patches often found along field edges or near the field entrance.

  

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