I planted 4-4.5 acres of soybean 2 months ago and they're about 20-24" tall as of right now. But thought i had killed everything in the field prior to spreading seed but i was wrong. Bought the cheap soybean seed and they're not RR. Local co-op told me I could mix Poast with Prime oil to get rid of the crabgrass, some other weeds, can't remember all that were on gallon jug. Has anyone used this method before and did it work?

poast is pretty pricey. I use the generic, clethodim. It's not the exact same chemical, but it works and it's a lot cheaper. It will definitely kill crabgrass. If you have a broadleaf weed problem also, poast or clethodim won't help. Also, if you have other stuff planted with the soybeans, you need to do a little more research to be sure the herbicide won't kill the other stuff

I used Post Plus and Prime Oil at recommended rates . Only made the crabgrass sick, didn't get a good kill. Tried it more than once too.

Only planted soybean in this field, no mix. I might just spend the $$ and try it out.

Poast plus sucks. Use clethodim with a quality ph lowering surfactant.

I agree and concur.