Answer:
1) Control fall-emerged marestail before the winter with a fall burndown. If fall seedlings are not controlled, they overwinter and are more challenging to control in the spring. If planting a cereal rye cover crop, 2,4-D and dicamba may be used.
2) Control all horseweed prior to cash crop planting. Effective POST options are limited, especially in soybean.
3) Use multiple effective herbicide modes of action (MOA). Vary MOAs in tank mixes and between applications. Using herbicides with different MOAs prevents selection of weeds resistant to certain herbicides like glyphosate or ALS.
4) Target marestail under 5 inches tall when they are most susceptible to herbicides. Scout early and regularly.
5) Include residuals at planting to prevent late-spring emerging horseweed plants.
6) Shade out spring marestail with winter annual crops or cover crops, narrow row spacing, or high seeding rates.
7) Hand-remove mature marestail before flowering, before it has a chance to produce and disperse its seeds.
8) Include corn or small grains in rotation, to increase herbicide options and compete with marestail for sunlight. Small grains and alfalfa also allow for mowing and harvesting as control options.
Step-by-step explanation: