Ryegrass, Italian


Italian ryegrass is an annual or biennial ryegrass that has become a problematic herbicide resistant weed in several states. It is considered a high concern herbicide resistant weed in Mississippi. While it is not native to the US, it is present in every US state. Some varieties of Italian ryegrass are sometimes planted as a companion crop for alfalfa, or in other seed mixes. See resources below for herbicide recommendations. Integrated weed management recommendations include:

  • Prevent entry by ensuring that all feed, seed, and equipment entering the property are free of ryegrass seed
  • Do not allow patches of Italian ryegrass to grow along ditches, fence lines, or other border areas; control them before they spread to the fields
  • Vary the effective herbicide sites of action (at least two) in tank mixes and change them up between seasons to decrease the chance of selecting for resistant populations

Herbicide Resistant Populations:

  • Group 1 (ACCase inhibitors)
  • Group 2 (ALS)
  • Multiple resistance: Group 1 + 2
  • Group 9 (glyphosate)
  • Multiple resistance: groups 1, 22 and 9
  • 10 (Glufosinate)
  • 15 (long chain fat acid inhibitors)
  • Multiple resistance: groups 1, 2, 9 and 22
  • 22 (PSI Electron diverters-paraquat-)

IWM Management:

Italian ryegrass is a problematic weed in cereals, grass seed crops, and grain crops planted no-till.  It can result in significant yield losses if this weed is not controlled. Farmers in the US struggle to manage this weed, particularly in areas where Italian ryegrass has evolved herbicide resistance.

To search for alternative or complementary weed management tactics to herbicides, an USDA-NIFA funded project started in 2016 at two locations: College Station, TX and Newport, AR. The experiment evaluated the performance of different IWM strategies in a long-term field trial. This study included crop rotation, comparing continuous wheat, with wheat-fallow (TX) or wheat-soybeans (AR). Strategies targeting weed seeds included Harvest Weed Seed Control treatment (windrow burning) as well as tillage in the form of disking after harvest. The combination of different IWM tactics, together with natural seed predation and common chemical options, resulted in a drastic reduction in the weed seed bank after four years.

In this video you will find the preliminary results from this large-scale field trial done in Texas. Final results will be discussed in future posts.

Researchers: Dr Muthu Bagavatiannan and Dr. Jason Norsworthy

Edits: Kara Pitmann and Mark VanGessel

Video: Claudio Rubione



USDA Plant Profile for Italian Ryegrass

Italian Ryegrass Management in Soybeans – Purdue University

Glyphosate-Resistant Italian Ryegrass Management Tips – Jason Bond, Mississippi State University

Italian Ryegrass in Wheat and Small Grains – Washington State University