Yes, I know, its June and we’re still talking about ryegrass. The unusually wet winter and early spring may have inhibited many sprayers from making timely PRE and early-POST applications on troublesome weeds like ryegrass.
Some populations have also survived the burndown application at planting, which has led to recent producer calls asking what can be done.
Nicosulfuron, found in Accent, may be an option for glyphosate-resistant ryegrass in corn, assuming it’s also not ALS-resistant. The label recommends postemergence applications on ryegrass under 6-8” for optimal control.
However, in late rescue applications we can use between 0.9-1.8 oz/A over corn less than 20”. Steadfast Q is a mixture of nicosulfuron + rimsulfuron that may have slightly better activity at 1.5 oz/A on corn under 20”, but in either of these options, mature ryegrass may only be suppressed at best.
This may at least give the corn a chance to reach canopy coverage and out-compete the grasses.
Applications of Liberty (glufosinate) may be an alternative option on Liberty Link varieties only. This isn’t often discussed because of the unfavorable cooler conditions often present when it’s needed for young weeds in early spring.
For best results, a tankmix of Liberty at 1 qt/A plus 1 lb/A atrazine must be applied during mid-day in full sun when temperatures are in the 80s. I wouldn’t expect control, but we may see a reduction in ryegrass seed production.
Use caution in fields where refuge corn is mixed in the population to make sure it has the LL trait.
Again, none of these are good options and, at this point, we may just have to live with it and expect a yield reduction. If you have ryegrass now, chances are, you’ll have it again next season, so I encourage you to plan accordingly this fall.