During the last few weeks, I have received a few inquiries about controlling bermudagrass prior to planting various row crops. An established stand of bermudagrass can be very difficult to manage. When dealing with bermudagrass burndowns, glyphosate rate and time of application are crucial. Here are a few points to consider:
1. When applying glyphosate in the spring, when is the best time of application? Generally, later applications are more effective after the bermudagrass has greened up and is actively growing (Figure 1).
2. Can bermudagrass be effectively controlled with 1 application of glyphosate? What rate of glyphosate should be used?
In previous UGA research, the most effective control of bermudagrass occurred when 3 applications of glyphosate @ 2 lb ai/A were applied (Figure 2). Obviously, this program would have to be implemented the year before planting a spring row crop.
I hope you notice that a single application of 4 lb ai/A of glyphosate applied in May was not very effective (38% control).
3. Growers who are relying on spring applications of glyphosate only will almost certainly have to follow up in-crop with 1 or 2 applications of a postemergence grass herbicide, such as Select or Poast (only in labeled broadleaf crops), or glyphosate (only in labeled GR-crops).
Consequently, those extra herbicide costs should be included in their budget plans. Additionally, it might take a few years of fighting before optimum bermudagrass control will be obtained.