Over the past several days, I’ve noticed several corn fields that are over-due for postemergence weed control. I expect these fields will get sprayed this week and stop the yield loss that is occurring. While it is too late to optimize yield in some of these corn fields, time is still available to protect soybean yields from weed competition. Considering that the weather forecast for the next week is generally hot and dry, it’s time to start planning and making postemergence applications in soybeans. The heat will make weeds grow faster and dry conditions will increase their competition for soil moisture, making every day count. Some research suggests soybeans can lose 1% of their yield per day after weeds reach the stage when they start to compete. Of course, the actual yield loss depends on several variables such as weed density and species. Nevertheless, weeds often begin to compete with soybeans by about the V3 or third trifoliate leaf stage. Under dry conditions, this competition could begin earlier. So, don’t delay and start making postemergence applications to protect soybean yields.