ManageMent guide foR italian RyegRass - Monsanto

italian
Ryegrass
ManageMent guide foR italian RyegRass
this document is intended to provide
information about this weed and guidelines
for control. as a tough-to-control weed,
knowledge about the biology and weed
control programs will help in management.
italian Ryegrass Biology
u Italian ryegrass is found in roadsides, ditches
and increasingly in fields. The plant is
palatable to livestock and produces forage.
However, Italian ryegrass has encroached
into fields, competing with wheat for
moisture and nutrients. Weed contamination
of harvested grain can cause considerable
price dockage. 1
u Italian ryegrass is distributed throughout
the U.S. It is widely adaptable to many
soils, but thrives on dark, rich soils in mild
climates. It does not withstand hot, dry
weather or severe winters, but can stand
fairly wet soils with good drainage. 4
u Italian ryegrass is an upright annual that
acts like a biennial or short-lived perennial.
It reproduces by seed and grows in winter
and early spring. Hairless seedling leaves
are shiny. The mature plant grows 1 to 4
feet tall. Terminal spikes are flat and
alternate along the stem. Long bristles
are on the spikelets. At least 10 florets
per spikelet differentiate Italian from
perennial ryegrass. 1
u Seeds are relatively flat and very light, so
they are easily transported by wind. They
are held reasonably tight to the flower
stem, and need some form of force to drop
them to the ground as individual seeds or as
part of the flower stem. 2
1 http://www.ipm.ucdavis.edu/PMG/WEEDS/italian_ryegrass.html
2 http://weedman.horsham.net.au/weeds/lolium_rigidum/lolium_rigidum.htm
3 Heap, I. The International Survey of Herbicide Resistant Weeds. Online. Internet.
May 15, 2008. Available www.weedscience.com.
4 http://plants.usda.gov/factsheet/pdf/fs_lopem2.pdf
5 http://www.ca.uky.edu/agc/news/2006/aug/ryegrass.htm
Weed environment
www.weedresistancemanagement.com
u Annual ryegrass is a prolific seed producer.
Italian ryegrass and wheat have similar
maturity, so without good control measures
the grass chokes out wheat in the field. At
harvest, seed is further dispersed across the
field by combines. 5
u As much as 85 percent yield loss has
occurred as a result of ryegrass competition
in wheat. One plant per square foot can
reduce yields by four percent. 5
u Widespread distribution of Italian ryegrass
and rapid, extensive development of
resistance may also be partly due to large
genetic variability in the species. 2
u When seed bank numbers are high and the
ryegrass becomes established early in the
growing season, problems occur. Ryegrass
produces large numbers of tillers and even
a low density of plants can return a mass of
seed to the seed bank. 2
u Glyphosate-resistant Italian Ryegrass
populations have been confirmed in
Mississippi and Oregon.

treatment Recommendations 1
Scout fields and control weeds throughout the season. Proper application timing protects yields, ensures correct use rate for
weed size and considers the impact of environmental conditions on performance.
Roundup Ready ® Corn 2*
u Start clean with a burndown herbicide or tillage.
Early-season weed control is crucial in corn to
maximize yield potential.
u Apply a preemergence residual herbicide such as
Harness ® Xtra or Degree Xtra ® , or other residual
herbicides at the recommended rate.
u Or apply a preemergence residual herbicide at the
recommended rate tank mixed with Roundup
WeatherMAX ® at a minimum of 22 oz/A in-crop.
u Follow either program with a postemergence in-crop
application of Roundup WeatherMAX at a minimum rate
of 22 oz/A.
u Tank mix other herbicides such as Accent ® , Equip ® or
Option ® to control emerged Italian ryegrass if you suspect
the ryegrass is resistant to glyphosate.
*Includes corn with Roundup Ready 2 Technology
Roundup Ready soybeans
u Start clean with a burndown herbicide or tillage. Tank
mixing with 2,4-D will help provide more effective
burndown control.
u An application of a residual herbicide will provide control
of a number of grass and broadleaf weeds in early season,
reducing the population of weeds that emerge and allowing
more focused control of tough-to-control weeds.
Minimize the Risk of Weed Resistance
u Start clean and control weeds early.
u Use Roundup Ready Technology as your foundation.
u Add other herbicides and cultural practices where
appropriate as part of the Roundup Ready Cropping System.
u Use the right rate at the right time.
u Control weeds throughout the season and reduce the
weed seed bank.
u In-crop, apply Roundup WeatherMAX at a minimum of
22 oz/A, and follow with a second application of Roundup
WeatherMAX if an additional flush of annual weeds occurs.
u Roundup WeatherMAX may be tank mixed with products
such as Select MAX ® , Assure ® II or Poast Plus ® if you
suspect the Italian ryegrass is resistant to glyphosate.
Roundup Ready flex Cotton and
Roundup Ready Cotton
u Start clean with a burndown herbicide or tillage. Tank
mix Roundup WeatherMAX with dicamba or 2,4-D
(consult label for plant back timing).
u Apply a preemergence residual herbicide, such as
fluometuron (Cotoran ® ) or diuron (Direx ® ), at the
recommended rate.
u In-crop, apply Roundup WeatherMAX at a minimum of
22 oz/A tank mixed with PARRLAY for residual control
of some grass and broadleaf weeds.
u Roundup WeatherMAX may be tank mixed with products
such as Select MAX, Assure II or Poast Plus if you suspect
the Italian ryegrass is resistant to glyphosate.
Rate your Risk, Know your options.
www.weedtool.com
u Answer 10 field-related questions
u Get your risk rating score
u Discover how to lower your risk
u Learn best practices for reducing general weed
resistance risks
Report incidences of repeated non-performance of any Monsanto branded herbicide to
your local Monsanto retailer or call 1-800-RounduP.
1This fact sheet is issued to clearly describe use recommendations permitted under FIFRA Section 2(ee) as not being inconsistent with product labeling, or is issued to highlight an approved use
from the product labeling. It is a violation of the federal law to use any registered pesticide product in a manner inconsistent with its labeling. Read and follow all precautions and use instructions
contained within the labeling. The applicable labeling for all products must be in the possession of the user at the time of application. Some recommended pesticide products are not registered in
all states. Check with the product manufacturer or your dealer for products registered in your state. The distribution, sale or use of an unregistered pesticide is a violation of federal and/or state law
and is strictly prohibited.
these recommendations are for all states except texas.
ALWAYS READ AND FOLLOW LABEL DIRECTIONS: Roundup Ready ® crops contain genes that confer tolerance to glyphosate, the active ingredient in Roundup ® agricultural herbicides. Roundup
agricultural herbicides will kill crops that are not tolerant to glyphosate. Harness ® brands and Degree Xtra ® are restricted use pesticides and are not registered in all states. The distribution, sale or use
of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. Check with your local Monsanto dealer or Monsanto representative for the product registration in your
state. Harness ® , Degree Xtra ® , Roundup ® , Roundup Ready ® , Select MAX ® , PARRLAY, and Roundup WeatherMAX ® are registered trademarks of Monsanto Technology LLC. All other trademarks are
the property of their respective owners.
© 2008 Monsanto Company 5F-8L-08-3138