Recent burndowns that are targeting Palmer amaranth with paraquat are working quite well on that weed. Unfortunately, that is not the case on some grass weeds like barnyardgrass, junglerice and crabgrass. Once those grasses get 4” or more in height paraquat often struggles to provide good control. This can be offset somewhat by applying full rates and making those applications of the evening. However, even then at times control is not ideal.
Even with the poor grass control with paraquat, it still should be the “go-to” for burndown at planting as the crop must emerge clean of Palmer amaranth. A plan to manage those escaped grasses should include an early POST application that consists of clethodim. About 15% of the junglerice populations in the state is glyphosate resistant thus the reason for clethodim. Glyphosate can be tankmixed with the clethodim which should do nothing but improve the grass control. However, be sure to not tankmix in dicamba with clethodim or clethodim + glyphosate as that often will result in very poor grass control.