First, be sure you are using a three way at full maximum rate. Be sure to calibrate carefully...try to hit between 100 and 110 percent of the max rate. Be sure to include a spreader or surfactant. You might want to spike it with some triclopyr. Or add some Octane to the mix. I tried some Ace three-way in late March on yellow rocket, and on the same weed four feet away about 10 days later, turned out to be cold both times and remained cold. Both treatments are having an effect...more later, with photos.