Control of heavy weed pressures show value of residual herbicides in Minnesota

Published on: 11:39AM Aug 04, 2009
While Minnesota corn growers started the season off well by averting the planting delays seen by much of the Midwest, the cold weather and lack of rain after planting has allowed for some difficult weed control challenges. Lambsquarters has been voted “Weed of the Year,” by retailers and growers who have been battling its presence in fields across the state. Due to a colder than normal spring, the lambsquarters had not yet germinated when growers cultivated their fields, which left thousands of seeds to take root alongside the crop. Growers who chose a post-emergence herbicide that combined glyphosate with residual control found a convenient way to manage the heavy weed pressures.
Using a residual herbicide provides extended control of lambsquarters and other prevalent broadleaf weeds in Minnesota like waterhemp and ragweeds. Now, after a week of above average temperatures and some rain, the corn is rapidly growing toward canopy and growers who used residual herbicides are satisfied with the length of weed control they’ve seen. Conversely, for growers who chose glyphosate alone, which provides no residual control, the heavy weed pressures seen this year may prompt them to rethink their 2010 herbicide plans to achieve season-long weed control.

As the corn crop in Minnesota neared complete canopy,
residual herbicides still held back heavy weed pressure.
Photo taken late June 2009, LaSalle, MN.