Once the crop has shaded the soil, weed seed germination stops, and your crop has gained the edge on weeds and is less vulnerable to competition for nutrients, sunlight, and water. For weed management in soybeans, especially narrow-row soybeans, a rotary hoe can be an effective tool. Rotary hoeing should be done while weeds are still in the white root stage. Wait until daytime air temperatures are warm and soybean plants are not brittle, then drive perpendicular or diagonally to the rows. Avoid hoeing during the first week after soybean emergence when cotyledons may be shattered from plant stems.
Rotary hoes are subject to greater variability in effectiveness compared with sweep cultivators.
Speed is an issue when hoeing. Don't drive too slow. The best results while hoeing are obtained at 7 to 9 miles per hour. Many producers could face a weed-control problem this year, whether from wind affecting spray coverage, rain, or for other reasons. If you have had a chemical application strategy that has not worked as well as you wanted, change your strategy a little bit.