Hybrids listed in this publication may be of acceptable maturity for southern Wisconsin and sandier, warmer soils in central Wisconsin. Hybrid trials are also conducted in Iowa, but these focus on the drier, warmer western and southern portions of that state. Early spring seedbed preparation followed by one or two shallow cultivations, just before planting sorghum will kill several generations of weed seedlings and give sorghum a chance to get ahead of the weeds. Timely cultivations of sorghum planted in 20-inch or wider rows during the early growing stages are highly important. Sorghum planted in narrow rows can not be cultivated, but it is a highly competitive crop and can dominate many weeds.
Several herbicides are available to compliment cultural and mechanical practices.
Other perennial weeds such as Canada thistle, milkweed and hemp dogbane should be suppressed the year before sorghum is planted. Several selective herbicides can be used in sorghum. Atrazine can be applied as a preplant incorporated, preemergence or postemergence herbicide. Application rates are similar to those used in com, as are the concerns of atrazine carryover. If crops other than com will be planted next year, do not use atrazine in sorghum.