When fall management fails to eliminate a red clover cover crop what are the options to manage it ahead of soybeans? Ideally one should plant the field to corn and take advantage of red clover’s nitrogen credit (The Ontario corn nitrogen calculator credits it for as much as 73 lbs N/ac). Planting corn also provides more herbicide options (Banvel II, Marksman, Callisto and Engarde, to name a few) that will control volunteer plants.
If you want to plant soybeans instead, managing the clover prior to seeding will be a priority, especially in non-GMO (IP) soybeans where there are no effective methods for control once the crop is out of the ground.
Below is a summary of red clover control with pre-plant soybean herbicides from 3 trials conducted at the Elora Research Station in 2004.
Figure 1 The ineffective control of red clover with a pre-plant application of 2,4-D Ester
What if I have clover in emerged non-GMO (IP) soybeans?
If red clover is not controlled prior to planting, it is near impossible to manage the clover in an emerged bean crop. My experience has been that red clover is very tolerant to Basagran (bentazon) and Pinnacle (thifensulfuron). Reflex (fomesafen) and Blazer (acifluorfen) provide the most foliar burn to clover but at best all that you can hope for is that the volunteer clover is set back and the soybean canopy closes and shades the volunteers out. I’ve seen variable results with Classic (chlorimuron-ethyl), but I wouldn’t expect anything more than some stunting.