Weed management in several areas of the province has been challenging.  Weather has prevented herbicides from being applied and from being activated. Early weed control remains critical for maximum yield, despite the weather.

Dr. Swanton at the University of Guelph has shown that corn plants have the ability to “see” weeds. To compete with weed pressure, corn plants reallocate resources within the plant by increasing shoot biomass and reducing root biomass.  The change in shoot to root ratio has been changed for the remainder of the season and translates to irreversible yield loss.   

What should you do?  For those who have not yet applied herbicides, do so as soon as possible. Producers who have herbicides applied but they have not been activated may wish to consider a contact herbicide to control emerged weeds. Herbicides applied will activate with a significant rain event. 

Emerged weeds significantly decrease yield early in the growing season.  Irreversible yield loss increases over time with weed competition. For maximum yield potential, weeds require management as soon in the growing season as possible. 

Shawn Winter, CCA-ON, Maizex Seeds Product Development Manager
Twitter: @SWinter_Maiz