438RR Roundup Ready® Alfalfa

  • Scientific name: Medicago sativa
  • Roundup Ready® Alfalfa
  • Unsurpassed weed control
  • Great forage yield potential
  • Superior forage quality
  • High multifoliate leaf expression
  • Germination salt tolerance
  • Excellent winterhardiness and persistence
  • Perfect 30 out of 30 Wisconsin Disease Rating Index
  • Available only in 50 lb bags

Quantity is per pound. Example: 1 = 1 lb, 2 = 2 lbs, 3 = 3lbs, etc. This is pure seed, not a live plant.

SKU 438RR Categories ,


Min. to Max. Annual Precipitation


Average Max. Height

438RR Roundup Ready Alfalfa is one of the latest roundup ready varieties that is a cleaner, high quality alfalfa. performs well over a wide range of conditions. Produces great forage yields and has a very fast recovery after cutting. Used for commercial hay, beef and dairy producers. REQUIRED to have a Monsanto royalty number in order to purchase.

438RR Roundup Ready® Alfalfa is not available for purchase on our website. You can, however, call us directly and order. Before we can ship Roundup Ready® alfalfa (Medicago sativa) you must have a Monsanto royalty number. Call us at 435.283.1411 and we will help you through the process – it is not difficult.

438RR (Medicago sativa) is one of the latest generation Roundup Ready® alfalfa varieties that lets you produce cleaner, higher quality alfalfa for greater profit potential. The simplicity and improved crop safety of using one herbicide with the widest window of application available, enables you to be in control instead of Mother Nature. 428RR alfalfa performs well over a wide range of environmental conditions and is adapted to all areas where 3, 4 and 5 fall dormancy varieties are planted. 438RR alfalfa also features a disease index rating of 30/30 and high multifoliate leaf expression for improved forage quality. Whether it’s for great forage yields, superior forage quality, or very fast recovery after cutting, 438RR alfalfa is the choice for commercial hay, beef and dairy producers who want to take advantage of Genuity Roundup Ready technology.

438RR Roundup Ready® Alfalfa is resistant to glyphosate herbicide which can be used to provide weed control. Roundup Ready alfalfa can provide high quality, weed-free forage with excellent crop safety and minimal harvest restrictions. The introduction of Roundup Ready alfalfa provides a new option for weed management in alfalfa. 438RR Roundup Ready® Alfalfa incorporates genetic resistance to the herbicide glyphosate (Roundup, Touchdown, Glyphomax, etc.) into the alfalfa plant. Similar to other Roundup Ready crops on the market today such as corn and soybean, a single bacterial gene that modifies 5-enolpruvylshikimate-3-phosphate (EPSP) synthase has been inserted into the alfalfa plant to allow resistance to glyphosate.

EPSP synthase is present in most plants and is an enzyme essential for protein synthesis and normal plant growth. When glyphosate is applied to susceptible plants it blocks EPSP synthase preventing the production of essential amino acids and the plant dies. However, in plants that are Roundup Ready, a modified EPSP synthase is unaffected by glyphosate and allows the plant to continue growing. There is little or no crop injury associated with glyphosate application and Roundup Ready alfalfa.

Importance of Weed Management

Alfalfa forage composition as affected by weeds can have significant impacts on protein content and overall feed quality (Cords 1973). Weed management in alfalfa is critical during stand establishment to ensure successful plant population. Alfalfa seedlings establish slowly and are very sensitive to competition for limited resources. Weed competition during establishment will reduce alfalfa seedling vigor and potentially reduce the alfalfa plant population, which can affect crop yield and quality throughout the life of the stand. In Pennsylvania, Stout et al. (1992) demonstrated that controlling weeds during the establishment year reduced stress on alfalfa, increased seedling weight and leaf numbers, and ultimately increased yields the following year. Leaf number and leaf content in alfalfa hay are direct indicators for digestibility, crude protein, and relative feed value (Kuehn et al. 1999). In addition, successful weed seed production during alfalfa establishment will potentially increase weed seed reserves in the soil, contributing to future infestations.

Once alfalfa is established and is successfully into the forage production period (after the first harvest), well managed alfalfa stands are generally vigorous and aggressive enough to compete well with later emerging weeds. In fact, over 95% of weed control in a healthy established alfalfa crop can be attributed to the alfalfa’s competitive nature. Thus, careful weed management during the establishment period of alfalfa is essential for maximum returns from an alfalfa crop over the life of the stand.

  • To maximize 438RR Roundup Ready® Alfalfa (Medicago sativa) production for yield and quality, weed management should be addressed. The most critical time for weed management in alfalfa is during establishment.
  • Yield longevity of an alfalfa stand depends on successful initial establishment of the crop since all subsequent harvests are dependent on initial stand density.

Stand Establishment

To maximize the benefits of 438RR Roundup Ready® Alfalfa, apply glyphosate at the 3 to 5 trifoliate stage. Weeds should be less than 4 inches tall. If weed problems persist, an additional application of glyphosate can be made up to 5 days prior to harvest. An initial glyphosate application is necessary at the 3 to 5 trifoliate stage to remove the small percentage of glyphosate-susceptible alfalfa plants that are present in the new seeding.

Stand Removal

Roundup Ready alfalfa removal prior to crop rotation is similar to conventional alfalfa varieties. Growth regulator herbicides such as 2,4-D and dicamba are the most common herbicides for removing alfalfa prior to crop rotation in no-till conditions. Deep tillage is also effective for removing established alfalfa stands.

Alfalfa (Medicago sativa) is an important perennial forage crop used around the world. Alfalfa is the fourth largest crop, in terms of acreage, grown in the United States behind corn, soybeans, and wheat. Unlike annual cropping systems, alfalfa management differs greatly due to its perennial habit of growth. The alfalfa crop will remain in the field for several growing seasons and will be harvested several times each season. Management will not only affect the first harvest of the crop, but will affect subsequent harvests within the life of the stand.

RR Alfalfa Ratings:

Bacterial Wilt Highly Resistant (HR) 5*
Fusarium Wilt Highly Resistant (HR) 5*
Verticillium Wilt Highly Resistant (HR) 5*
Anthracnose-Race 1 Highly Resistant (HR) 5*
Phytophthora Root Rot Highly Resistant (HR) 5*
Aphanomyces-Race 1 Highly Resistant (HR) 5*
Pea Aphid Highly Resistant (HR)
Stem Nematode Moderately Resistant (MR)

*Based on the Wisconsin Disease Rating Index. This is a 1 to 5 ranking with 5 being the best.

Fall Dormancy 4.0
Winter Survival 1.0 (Excellent)
Salt Tolerance Germination
Root Type Tap
Recovery After Cutting Very Fast

*** Click on the “Quick Plant Facts” tab for more information or visit: Weed Management for 438RR Round Up Ready Alfalfa

For more variety options click here: Alfalfa

Helpful Links

Additional information about this product can be found on the academic websites linked below.


Many plants have more than one common and scientific name. We've listed a few of them below.

  • 438RR Roundup Ready® Alfalfa
  • Medicago sativa

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Right: Company founder Lloyd and his wife Paula Stevens in a wildflower seed production field circa 1977

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