Italian ryegrass continues to be the most problematic weed in Kentucky wheat and no-till corn acres. Control of this problematic weed starts in the fall when the majority of our populations begin to emerge.  In our no-till corn acres, we have traditionally relied on spring burndown applications for control of winter annuals, including ryegrass. While this strategy is highly effective against most winter annual weed species, Italian ryegrass is now challenging this strategy as spring burndown failures increase on an annual basis. The use of a fall burndown and/or residual can be a step in the right direction for a complete management program for this problematic weed.

In our wheat acres, the adoption of pyroxasulfone-based products such as Anthem Flex, Fierce EZ, and Zidua has shown great promise for controlling fall-emerging ryegrass populations.   While this strategy has been successful, there are concerns that we are pushing ryegrass populations towards spring-emerging cohorts. Thus, we need to begin monitoring emergence of ryegrass populations in our wheat fields and implement programs that can capture control of this problematic weed at its peak emergence pattern.

The following data has been collected over the past year to help determine the best recommendations for controlling ryegrass starting in the fall for both wheat and no-till corn acres.   My recommendations for ryegrass control using this data and your knowledge of ryegrass emergence in your fields are at the end of this article.

Table 1. Visual ryegrass control in a Simpson County wheat field on June 10, 2025, following residual application timings of Anthem Flex and Fierce EZ. Population represents a mixture of a fall and spring emerging ryegrass population with a tolerance to spring applications of Axial Bold.  Spring applications of Axial Bold resulted in no change in ryegrass control in this trial (data not shown).

• Applications of Anthem Flex resulted in 87 to 93% control of Italian ryegrass regardless of timing of application. Both the “Pre only” and “Split” applications of Anthem Flex resulted in acceptable control at the end of the growing season.
• Applications of Fierce EZ resulted in 33 to 72% control of Italian ryegrass at the end of the growing season.
• ONLY the 6 fl oz of Fierce EZ applied 14 Days PrePlant was comparable in control to the Anthem Flex treatments.
• All split applications of Fierce EZ resulted in less than acceptable control of Italian ryegrass, regardless of the split ratio and/or the inclusion of metribuzin.

• Applications containing residual herbicide resulted in 55 to 83% control of Italian ryegrass.
• Treatments containing only glyphosate or paraquat applied in the fall resulted in 26 to 30 percent control of Italian ryegrass.
• The use of Command represents an option for field going to no-till soybean and alternative residual herbicide site of action for controlling Italian ryegrass.

• All treatments containing glyphosate or Gramoxone (paraquat) resulted in 86 percent or greater control in the spring.  These results are in contrast to the UKREC treatment, due to the difference in Italian ryegrass emergence at the two sites.
• The inclusion of a residual herbicide did not increase control of ryegrass in the spring, likely due to the majority of ryegrass emerging prior to the application on November 15, 2024.

Recommendation for The Fall of 2025

These are my recommendations for those farmers dealing with Italian ryegrass based on our research results

Recommendations for Italian ryegrass Control in Wheat

• Knowledge of the emergence patterns of ryegrass in your wheat field can be extremely beneficial in choosing an effective program for controlling Italian ryegrass.

• Fields with primarily fall-emerging populations of Italian ryegrass should be managed with either Anthem Flex applied PRE or Fierce EZ applied 14 Days Preplant.  It should be expected that some escapes will occur and an application of a Axial Bold can still be beneficial on populations still susceptible to this postemergence herbicide. 

• Fields with a mixture of a fall and spring emerging population should be managed with a split application of Anthem Flex.   The inclusion of metribuzin with the postemergence application of Anthem Flex can increase control of any ryegrass escaping the initial residual application.  Again, a late spring application of Axial Bold is still beneficial on populations that are still susceptible.

• It is NOT recommended to split application of Fierce EZ.

IMPORTANT REMINDER ABOUT DRY SOIL CONDITIONS and RESIDUAL HERBICIDES

• Regardless of whether you choose to use Anthem Flex, Zidua, or Fierce EZ; these residual herbicides must receive an activating rainfall shortly after application to successfully suppress ryegrass emergence. 

• The application of any of the three residual products to a dry soil seedbed followed by a heavy rainfall event can result in significant crop injury.

• Soil moisture conditions and rainfall forecast should be monitored closely when planning the timing of wheat planting and applications of residual herbicides for Italian ryegrass control.

Recommendations for Italian Ryegrass Control in No-till Corn

• Farmers dealing with a primarily early fall emerging population of Italian ryegrass can benefit from a simple fall burndown application of either glyphosate or paraquat (Gramoxone).

• The use of residual herbicides in the fall is the most beneficial for those farmers dealing with an Italian ryegrass population that has a mixed emergence pattern of both fall and spring emergence.

• Farmers dealing with a highly suspected or confirmed glyphosate-resistant Italian ryegrass population should apply a fall application of a tank mixture of paraquat (Gramoxone) plus either Boundary or Helmet MTZ.   We know that paraquat and metribuzin have synergistic activity on Italian ryegrass, thus the use of a residual premix with metribuzin will be beneficial.

• Regardless of fall applications, plan to follow up with a spring burndown application of either glyphosate or paraquat to control any escapes or spring-emerging plants. 

Recommendations for Italian Ryegrass Control in No-till Soybean

On acres rotating to full-season soybean, it is recommended to use Command as the fall residual herbicide.   Command represents an alternative herbicide site of action for control of Italian ryegrass and breaks the heavy reliance on group 15 herbicides for ryegrass control on wheat and corn acres.