I have been getting several questions on the best options for spring removal of alfalfa in no till fields. While fall applications have been shown to be most effective, logistical reasons inevitably occur which require spring removal in some fields. Many of the same herbicides used in the fall are also effective in the spring and are listed in table 1 along with rate ranges and plant-back restrictions for field corn. Note that the expectation should be for reduced control compared to fall timings, but results will vary considerably based on the stage of development of the alfalfa and temperature after application. As a rule of thumb, the longer one waits to spray a field, the better the control should be as plants will have more leaf area, will translocated more herbicide to the crown/root, and the temperature will be warmer so more herbicide will be absorbed into the plant.

 

Few studies have looked at spring timings, but one from Michigan State found spring applications of 2,4-D or dicamba provided 83% and 94% control one month after treatment, respectively. If roundup ready alfalfa is trying to be eliminated, obviously glyphosate should be avoided from the tank-mix. Many studies throughout the United States have shown the effectiveness of other herbicides (specifically the ones listed in table 1) at removing alfalfa. Future management plans for the fields should also be taken into consideration, as these could prevent any yield loss from alfalfa even if plants are not all killed by the early season treatments.

  ¹ Note that product labels vary in the amount of glyphosate that they recommend for removal of alfalfa, with some listing a maximum rate of 0.75 lbs ae/A. Others may allow for greater than 1.5 lbs ae/A, but will not allow the forage to be harvested or grazed. Please read the label carefully before application.