Cover crop weed control

By James Hoorman, Hoorman Soil Health Services

A new study by Purdue University, Dr. Bill Johnson shows the benefits of cover crops for weed control.  Cover crops are known to control grasses and marestail, but Dr. Johnson wanted to document other weed control benefits.  For example, can you control weeds with out residual herbicides?  What other weeds do cover crops control? 

Dr. Johnson found residual herbicides may not be needed if crop residue is high enough to suppress marestail and annual grasses weeds.  For other broadleaf weeds, the cover crop residue was not enough to suppress broadleaf weeds. The cover crops plus residual herbicides were 100% effective at controlling weeds in his trials.  Cocklebur was a problem weed which required the full rate of herbicide plus the cover crop residue to control it.

Dr. Johnson discovered several other important weed facts about cover crops.  Planting green or planting soybeans into cereal rye later had a much higher success rate than terminating the cover crop early. … Continue reading