By Dave Nicolai and Tom Peters et.al
While it is too late to control weeds in row crops this year, there is still time to limit weed seed production and prevent additions to the weed seedbank. Combine harvesters are notorious for spreading weed seeds. Hand-pulling or mowing weed patches are some of the last lines of defense before harvest.
Surveys of Private Pesticide Applicators (Figure 1) across Minnesota show that although a smaller percentage of respondents report they harvest weed areas separately (5 to 10%), a growing percentage of respondents report hand-pulling weeds as part of their weed management program (39% in 2024, the highest percentage reported since 2017). Taking some extra time now through these tactics can pay dividends for weed management in the upcoming years.
Weed biology is important
Know the biology of the weeds you are trying to control. Although waterhemp can produce 250,000 to one million seeds per plant, over 95% of the seed bank can be degraded in 4 years if waterhemp is prevented from producing seed and replenishing the seedbank during this time. The giant ragweed seed bank is degraded even faster, with over 95% degraded in just 2 years. However, a few weed escapes can produce enough seed to replenish the seedbank and negate past weed control success.
Source : umn.edu