How long does it take for herbicide to stay on before the rain?
It has been difficult to find a good time for burndown applications this spring because of the weather.Delayed field work can affect the efficacy of burndown herbicides.If you keep an eye on the weather forecasts and find windows of optimal conditions for herbicide applications, you can assure the best results.
Recommendations on how much time must be spent between application and subsequent rain are included in the labels.The rainfast period is when there is a lot of rain.
Good growing conditions are the basis of the herbicide rainfast ratings.Poor conditions may require a longer interval between application and any rain to ensure adequate herbicide translocation within the weed.Any amount of rain soon after spraying can have an effect on weed control.When it rains before it's rainfast, the performance of the herbicide will be reduced.
There are questions about the effects of temperature fluctuations on the performance of burndown herbicides.Depending on the target weed, the likelihood of decreased weed control will vary.Glyphosate performs well under a wide range of temperatures.When the temperature is 60-75F, the best performance occurs.
The growth of weeds slows when the temperature is less than 60F.The rainfast period is increased and the start of symptoms is slowed.If the temperature is less than 40F, don't applyGlyphosate-based herbicides.It is advisable to avoid spraying if a severe frost is predicted.Control may be reduced if the weeds are damaged or stressed.
Waiting for better weather conditions is the ideal solution.If weed size or other circumstances dictate that the field be treated now, select a herbicide with excellent efficacy on the target species.When plants are actively growing, reduced rate treatments are more likely to provide acceptable control.
See the 2020 Guide for Weed, Disease, and Insect Management in Nebraska for more information.
If you're planting 2Xtend soybean, burndown application of Engenia/FeXapan/XtendiMax should only be made.