I've always heard, and tried to follow, the thought of spraying roundup in the middle of the day or early afternoon. But now I'm in a pickle. I'm needing to spray my fields but we're working 7 days. The question is how late in the day, maybe even into the evening, can you spray and expect a good kill? I've never sprayed after dark but that may be the only time available this year.

Spraying during “banking hours” 9-5 is always best. Spraying at night is fine so long as you don’t have a temperature inversion. You can get a drift retardant at your local Coop that helps reduce drift issues

Spray when you can. Why would you get a poor kill by spraying after dark?

Also spraying with a boom is much better than a broadcast nozzle if that’s an option

Kill is not an issue. Risk of drift and off target damage. I’ve killed fruit trees spraying at night

The reason I've always thought it better not to spray after dark comes from hay-making days years ago. If we had to work hay after dark, we would always stop when the dew started forming. I didn't know how the plant would absorb the spray if there was dew on the plants. There is no worry about overspray killing something I want to keep in the areas I need to spray.

If you are concerned about dew just bump your rate a lil

Same question was asked not long ago. IIRC, 257weatherby says spray anytime (I assumed in daylight hours) with glyphosate. He ain't never lied to me and he deals with these chemicals daily. It's what's wrong with him