I've been reading some other threads to try to get ideas but, I'll just put it out there: I've got a bunch of weeds where I keep my equipment, and the owner of the lot asked me to take care of the weeds. I usually do just tree treatments, and not herbicide applications so I'm not extremely knowledgeable on the subject. The weeds are sunflowers and Whatever this is. Tried to look it up online and in my books, couldn't find it. I'm in northern Colorado. Anyway, he wanted me to use a soil sterilant and just be done with it (it's about a 1 acre flat gravel lot with clay soil, no trees or water around). I don't feel real comfortable with the soil sterilant so I was thinking of doing a pre-emerge in the late winter, and then put two application of Roundup Promax down later in the season when needed. What are your opinions? What would be a good pre-em to use in this situation? Very much appreciate any help.