Clearly, one weed many have had trouble with in 2018 is ryegrass. Questions began months ago and continue today. Questions have ranged from tactics to burn ryegrass down before planting to how to control it in a standing corn crop. What has become abundantly clear is that glyphosate is no longer an effective burn down option for ryegrass.
One reason I feel more are having trouble with ryegrass this spring is because of the higher rates of dicamba used for burndown in Xtend crops. Those higher dicamba rates tankmixed with glyphosate are likely decreasing the effectiveness of glyphosate on ryegrass. Adding clethodim in with the glyphosate and dicamba tankmix has been the most effective way to control ryegrass in a burndown. The rate needs to be at least 12 ozs/A of Select Max.
The plant back to corn after that rate of Select Max is 30 days. Therefore fields that are to be planted to corn may want to go with a sequential application of Gramoxone instead. The sequential application provides best results when they are sprayed 7 to 10 days apart.
The question on how to control ryegrass in a standing corn crop really has no “sure fire” answer. If the corn hybrid is Liberty Link then Liberty at a quart rate can be effective. Please keep in mind when utilizing Liberty in corn applications in May is that air temperatures can be too cold for Liberty to be effective. In order to get the best ryegrass control with Liberty, try to pick a warm spell where temperatures are in the mid-80s and apply it during the middle of the day. The other option is Steadfast Q which can be effective on ryegrass even at cold temperatures. The catch is that some ryegrass in the state is ALS-resistant so Steadfast Q will not be effective in those cases.