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Rainfastness for Postemergence Herbicides in Horticultural Crops

The following list was compiled by Katie Jennings, David Monks, Wayne Mitchem, and Roger Batts  from the Department of Horticultural Science, NC State University.  I had not seen such a list before and have had several questions on time from application to rain for several postemergence herbicide applications.  I thought this would be of interest to have on hand.

Rain or irrigation soon after application of postemergence herbicides can result in reduced weed control.  The following table is a guideline for the minimum time which should occur between application of postemergence herbicide and a following rain or irrigation.  In most cases, this information was taken from the respective herbicide label.  Follow all guidelines on the herbicide label.  This information is not to replace information on the herbicide label and is subject to change.

Herbicide                              Time

Aatrex                                    *

Aatrex Nine-O                         *

Aim                                        6 to 8 hours

Alanap                                   4 to 6 hours

Amine 4                                 *

Assure II                                1 hour

Atrazine 90 WDG                    *

Basagran                               4 hours

Betamix                                 6 hours

Bicep II Mangum                    *

Bicep II Magnum FC               *

Boa                                      30 minutes

Desicate II                             *

Defol 5                                  24 hours

Diuron 80 WDG                     *

Envoke                                 3 hours

Ethrel                                   *

Evik                                      *

Fusilade DX                          1 hour

Galigan 2E                           *

Glyfos                                  6 hours

Glyphosate Original               6 hours

Glyphosate                           6 hours  

Goal 2XL                              *

Gramoxone Extra                 30 minutes

Gramoxone Max                  30 minutes

Guardsman                           *

Harmony GT                        1 hour

Kerb                                     *

Lorox DF                               *

Maleic Hydrazide                   *

Matrix                                   4 hours

Orchard Master                     *

Permit                                  4 hours

Poast                                   1 hour

Poast HC                             1 hour

Poast Plus                           1 hour

Prep                                    6 hours

Pursuit                                 1 hour

Pyramin DF                          6 hours

Pyramin SC                          6 hours  

Reglone                               30 minutes

Rely                                     4 hours

Roundup Original and
     generic glyphosate           6 hours

Roundup Ultramax                2 hours

Roundup WeatherMax          2 hours

Sandea                               4 hours

Select                                 1 hour

Sempra CA                         4 hours

Sencor                                  *

Spin-Aid                              6 hours

Stinger                                6 hours

Touchdown                          6 hours

Touchdown 5                       6 hours

Touchdown Pro                    6 hours

UpBeet                               6 hours

*No information on rainfastness on label, allow at least 6 hours for these products.

(Bill Stall, Horticultural Sciences Department - Vegetarian 04-07)