Controlling thistles in corn
Thistles are sometimes called “emotional weeds”. It’s not because they feel anything, but because they can spark some strong reactions when spotted in a field.
Classified as noxious weeds in Ontario,1 Canada thistle and sow thistle are incredibly strong competitors for moisture, nutrients and light. Even small populations can reduce crop yields significantly – Manitoba Agriculture reports one study showing that a mere 14 Canada thistle shoots per square metre can reduce wheat yields by 38%.2
Why are they so difficult to get rid of? Mostly because they’re built for survival.
Controlling thistles in corn – indeed in any crop – requires a multi-year approach and a strong focus on an integrated pest management plan that uses multiple modes-of-action to slow resistance, particularly if you’re growing glyphosate-tolerant corn.
An effective control plan starts with managing thistle top growth to lessen crop competition and prevent seed production. Using herbicides with systemic activity can also help to diminish the plants’ undergound energy stores over time.
Lontrel™ XC herbicide from Corteva is a Group 4 systemic product that translocates throughout the plant for more effective, long-lasting thistle control.
Thistles are tenacious survivors and difficult to control for a number of biological reasons. A multi-year, multi-crop, multi-herbicide approach can help weaken the extensive underground root system and energy storage, but annual efforts to control top growth is key to protecting corn yields.
*Do not apply Lontrel XC to sweet, seed or popcorn.
**Tank mix designed only for glyphosate-tolerant corn hybrids.
1Ontario Ministry of Agriculture, Food and Rural Affairs. Noxious weeds in Ontario. http://omafra.gov.on.ca/english/crops/facts/noxious_weeds.htm
2Manitoba Agriculture, Canada thistle information page. https://www.gov.mb.ca/agriculture/crops/weeds/canada-thistle.html
3Alberta Agriculture and Forestry. Canada thistle Pest Selector page. http://www.agric.gov.ab.ca/app107/loadPest?action=display&id=69