Last fall I was wondering how late was to late. Full rate of credit extra and just a touch of 2-4d used to burn down an old hay field. Had a killing frost many times already and day time highs of mid 30's and lows in the upper teens. Waited for frost to melt off the grass then sprayed around 1 or 2 in the afternoon. That night froze again then snowed a few days later and stayed all winter. Things just started to green up here the past few days and the field I sprayed has a perfect kill. I was surprised that it burned down as nice as it did. It was a perfect test as it was only ten acres and had the chems and the sprayer needed to be cleaned for winter anyway.