Most labels tell you to apply early morning or late evening to void extreme heat. So the manufacturers apparently say it doesn’t matter.

 

It think if you apply it correctly there is only so much that you’ve applied that will be taken up. Keeping it wet with dew wouldn’t make it uptake more in most cases. It’s a usually a case of temperature when it’s discussed or labeled. Something will work better cooler/hotter or cause less damage and stress.

now, there are plenty of things you can apply that when used with a MSO or oil type, it will help adhere to the blade longer. Those instances it does help concerntrate the full spray into the plant rather than have run off.