Rain Needed For Herbicide Activation
Here is a 2007 ISU study which cites a 1997 UI site. The chart tells it all.
Bottom line - 1" for full control of foxtails. 1/2" gives 85-90% control. Up to 1/4" shows about 50% control.
So, it looks like 1/2" gives most of the results but for full results we need an inch.
Re: Rain Needed For Herbicide Activation
Thanks for the link Jim. I had my corn sprayed a week and a half ago with Roundup and Resolve Q. Some of our beans were sprayed last week with Roundup and Classic. I am already seeing a few weeds starting to emerge in the corn. Our last rain was May 6th if you don't count the five minute shower yesterday that yielded less than a tenth.