I applied this product in October as recommended and it was followed by a good soaking rain, so I felt good about the timing of the application. It worked very well at providing pre-emergent control of annual bluegrass, as I did not see a single plant sprout this year. However, since the primary reason I purchased this product was to control lawn burweed, I am very disappointed in the results. I had more lawn burweed this year than in previous years. There were lots of other annual winter weeds that sprouted as well, so I am not happy with the end result. It also stains everything yellow, including my spray tank.