Avoid Resistant Lambsquarters in Your Field

No one wants a field to look like this, especially not their own.  The fact is, glyphosate-tolerant lambsquarters has become a growing concern for growers in the Midwest, and is becoming a weed to watch for growers in the Southwest as well. 

Lambsquarters escapes have been a red flag for growers across the U.S., especially the Midwest. Although it has not been confirmed resistant to glyphosate, several environmental factors affecting control have given it an advantage over the herbicide. Many growers are applying the herbicide too late, allowing lambsquarters to get too large, in order to time their application to other weeds. Lambsquarters is a competitive weed that has challenged growers for some time. The threat of it developing resistance to glyphosate adds pressure to keep it under control.

In the South, some are also seeing lambsquarters pop up. In an article in the Southwest Farm Press, Texas Extension Agronomist Todd Baughman, with the Texas Cooperative Extension at Vernon, warns growers that resistance in weeds is growing at an alarming level, and suggests Best Management Practices to combat it. 

He also discusses some of the many contributing factors to glyphosate resistance development, such as no crop rotation, no herbicide rotation, presence of a highly susceptible species, sole dependence on herbicides for weed control, reduced tillage, narrow-row planting (which eliminates option of in-season cultivation), more acres per grower, fewer herbicide modes of action, reduced use of soil-applied herbicides and reduced labor and equipment used in weed control programs.

Weed resistance management is the first step in controlling lambsquarters and other weeds. Syngenta recommends the following:

• Scout fields
• Use effective herbicides with different modes of action
• Use full rates
• Apply when weeds are small (less than 6 inches)
• Control weed escapes
• Avoid spreading seed through machinery or persons by thoroughly cleaning machinery and  clothing between fields
• Control weeds in fence rows and ditches

Click here for more thorough Syngenta recommendations on managing resistant lambsquarters.

Click here for a bulletin on lambsquarters control from Purdue University.