The best way to keep tabs on how well your herbicide and hybrid program is working is to monitor crops and keep records on the dates and weather conditions at the time of spraying and around that application timing. In years of poor crop prices and dismal cropping conditions, some key inputs in farming are thrown out the door such as better crop seed and weed control. However, these two inputs alone substantially make or break a farm in the long run. Good, clean, high-germ crop seed is most important. Seed will determine your stand, plant vigor and yield.
Weed control done now affects the farm for years, sometimes decades.
Some weed species produce an amazing number of viable seed. Minnesota studies done back in the late 1940s did weed-seed counts on 24 different plots across four locations that found 98 to 3068 viable weed seed per square foot down six inches deep in the soil. On a per acre basis, this weed seed bank is between 4.3 million to 133 million seeds in the upper plow layer. Weed escapes can add substantially to this weed bank.