Re: Dry time for 2 4 D
Amine 400 is a one dimensional herbicide of 2-4 D. A three way herbicide will yield much better results, i.e. Vessel, Trimec or Mec Amine D. If you have hard to kill weeds such as ground ivy and wild violets consider a better product such as T-zone.
4 hours is the usual window for being rainfast, many are pretty safe once dried.
Timing is important when applying herbicides, the best time is early Spring when weeds are actively growing and before the grass has ever been cut. The target weeds will have much more surface area absorbing the herbicide. Fall is also a good time for application as the plant will translocate the herbicide to the root.
Summer is pretty poor as the weeds will have a waxing coating and will not absorb the material well. As others have said, use a surfactant such as Li-700.
John Deere 2305, 62" deck, &47" snowblower.
JD X758 60" HC deck
Simplicity Conquest, 50" w/turbo bagger
Husqvarna , OE Tree Monkeyed 346XP, 346XP ported, 357XP x 2, 562XPG, 372XPG ported, 288XP Lite ported, 395XP
Jonsered 2159 ported
Echo PPT 266
Stihl 028 super, rebuilt and ported
Echo PPT-266 pole saw
Iron & Oak Commercial w/ log lift, hydro 4 way
Nielsen 100B for rakers
F250 8' box, 18' trailer w/5200 axels