Kansas State University weed specialist Sarah Ganske is urging farmers to keep a watchful eye for next year’s weed problems as they bring in this year’s harvest.
Ganske, a K-State Extension weed scientist, said growers should use time in the combine or grain cart to scout for weed escapes, or weeds that survived this year’s control program, and to improve equipment-cleaning practices.
“We often don’t think about weed management in the fall,” Ganske said. “But actually, it’s an important part of the cycle of having good weed management programs across all your acres.”
Producers can learn a lot about weed control as they move through fields at harvest, Ganske said. Identifying which species survived and where they are located can help growers predict future weed pressure, identify potential herbicide resistance and determine whether to adjust herbicide programs or add fall cover crops such as cereal rye.
Pigweeds, including Palmer amaranth and waterhemp, remain among the most troublesome weeds. Ganske also listed morning glories and velvetleaf as concerns. Hophornbeam copperleaf is a newer problem, particularly for corn producers because it emerges later in the season.
Weed escapes often occur in low spots where the crop is less competitive, on headlands that experience more traffic and disturbance, and along fence rows.
Those patterns can help farmers identify areas of differing productivity and determine whether zone management is needed. For example, growers could increase herbicide rates or change products in certain parts of a field rather than treating every acre the same.
Sudden changes in the size or location of weed patches should raise a red flag. Growers should take note when a weed patch changes in size or appears in an unexpected location, Ganske said, as those areas could indicate problems that require closer attention.
While scouting for problem areas, growers also should consider how to avoid moving weed seeds from one field to another.
Ganske recommends planning harvest so heavily infested or potentially resistant fields are harvested last or at the end of the day, when there is more time for thorough cleaning. Cutting around weedy patches can help prevent combine plugging and limit the amount of weed seed entering the machine.
Cleaning equipment between fields is critical to reducing the spread of weed seeds. Most seeds accumulate in a few areas of equipment, so focusing on those spots can have a significant impact.
Rainy days during harvest can provide an opportunity for more thorough equipment service and cleaning. Ganske also advised growers to check grain cart tires, which can pick up seeds, and to ensure tillage and planting equipment is not dragging weed parts from one field to another.
Source: Kansas State University, "K-State weed specialist urges fall scouting to get ahead of next year’s weed problems"