Managing Italian Ryegrass Escapes In Corn

DR. TRAVIS LEGLEITER

LEXINGTON, KENTUCKY

Italian ryegrass escapes are again a common site in Kentucky no-till corn fields. This scenario is unfortunately becoming more of a common site in Kentucky.  While the majority of ryegrass in our corn fields was controlled with fall and spring burndown and residual applications, there seems to still be some “clumps” of ryegrass still existing in many fields. There are also some fields with overwhelming amounts of escapes as well. 

The current question is what do we do now?  Especially in most cases where the corn is already emerged and ryegrass plants well on their way to reproduction.  Unfortunately, once corn emerges our options become very limited.  The first thing a grower or consultant must know is what herbicide tolerance traits are in the corn hybrid planted.  Below are recommendations for managing ryegrass escapes based on the herbicide tolerance traits in the corn hybrid.  These recommendations are based on research conducted at the University of Kentucky Research and Education Center in 2022 on ryegrass escapes that ranged from 12 to 52 inches in height with an average height of 31 inches (Data available in Figure 1).

 Roundup Ready Hybrids

Nicosulfuron is about the only option in this scenario.  We found in our 2022 study that the addition of rimsulfuron or an HPPD inhibitor such as topyralate provided marginal increases in control.  Unfortunately, in this scenario, suppression rather than control should be the expectation. 

Recommendation:

• 1.5 oz Steadfast Q 
  or
• 3.4 fl oz Katagon
•  

Roundup Ready & Liberty Link Hybrids

Glufosinate does surprisingly well on large ryegrass plants and appears to be one of the better options for ryegrass escapes if you have a Liberty Link Corn Hybrid.  The addition of nicosulfuron (Accent Q) and/or an HPPD inhibitor (topramezone or tolpyralate) did not necessarily increase control, but may be included to provide an additional site of action.

Recommendation:

• 21 fl oz Liberty Ultra
  or
• 32 fl oz generic glufosinate (Interline, Cheetah, Forfeit, Surmise, etc.)
  
  Optional tank mix partners*
• Accent Q (nicosulfuron)
• Steadfast Q (nicosulfuron + rimsulfuron)
• Impact (topramezone)
• Shieldex (tolpyralate)

*Products such as Katagon (nicosulfuron + tolpyralate) and Sinate (glufosinate + topramezone) offer convenient premixes.  See Figure 1 for performance of these products.

Enlist Corn Hybrids

Enlist corn hybrids offer not only glyphosate and glufosinate tolerance, but also tolerance to quizalofop (Assure II) offering an additional option for ryegrass control.   If you have an Enlist corn hybrid we would recommend the use of Assure II at 12 fl oz/A plus glufosinate and/or nicosulfuron at the rates mentioned in the above sections.   ∆

DR. TRAVIS LEGLEITER

UNIVERSITY OF KENTUCKY