by Mike Plumer, University of Illinois Extension

Establishing Ryegrass

Fields need to be weed free when the ryegrass is seeded. In the fall, winter annuals are becoming established and are very difficult to see. Henbit, chickweed, cheat, downy brome and winter annual barley can become very competitive with the germinating ryegrass. If the field has a history of winter annuals, a low rate herbicide application before planting will ensure a clean field and quick start for the ryegrass. Select a field that will not have winter wheat in the rotation.

No-till drilling will give the quickest stand of ryegrass with a reduced seeding rate and seed depth should be ¼ to ½”. Broadcast seeding with an airflow spreader allows ryegrass to be mixed in fertilizer and gives a uniform spread of the seed and fertilizer. This reduces the time and expense that drilling requires. The main drawback is that emergence is weather dependant and requires 3-5# more seed per acre. Fertilizer buggy seeding requires that everything be double spread to ensure that the ryegrass seed is uniformly distributed due to the difference in weight between the fertilizer and the seed.

Date of Seeding

The rule of thumb is as soon as possible after crop harvest. From Interstate 64 south, the seeding dates that have worked are September 1 to October 15th. Plantings after the October 15th date are subject to problems with stand loss, slow growth, and less winter hardiness. Earlier seedings may get too large and reduce the winter hardiness. Drilling the ryegrass ensures quicker germination and emergence (often 7-10 days compared to broadcast), better root development, quicker stands in poor field conditions, improved winter hardiness, and therefore allows for a later planting date and lower seeding rates. The addition of 30# Nitrogen/ A. at planting greatly increases the vigor of the ryegrass seedlings, significantly increases the top growth and establishment, and is recommended when seedings are delayed to October 15th or later. This nitrogen fertility can be part of the fall fertilization program if diammonium phosphate is used and the nitrogen component is very little additional cost.

Seeding rates for drill establishment are 15-18#/A. Broadcast seedings need to be 18-20#/a and increased to 25#/A by October 15th or later.

Growth and Development

If the interest is in having a ground cover for the winter, then the ryegrass must be established before October 1st and needs 30#nitrogen/ acre. After this date most ryegrass will not develop more than 2 or 3 leaves going into winter. The stand may look thin and poor, but will develop roots all winter and grow rapidly in the spring. It has been observed that October planted ryegrass may only have 2 leaves by December, but measured root development has been 10-14” deep in fragipan soils. So long as the roots are not frozen, some development occurs during the winter.

By April 9th it has been observed that most of the root growth in depth has occurred. Rooting in first year no-till fields has been in the 28 to 31” range for fragipan and claypan soils. After 3 years of no-till crops and ryegrass cover crops each year, rooting has been 45-52” deep. At this time top growth is normally 5-8”.

Ryegrass Control

Control of the ryegrass cover crop is best done when the plant is small, 4-8” in height. That means the first part of April. While one herbicide application can work, the herbicide program should plan for two applications. Annual ryegrass has the ability to regrow since it has such a large root mass. Even though it is small it requires full rates of herbicides. Low rates will often stress the plant making it more difficult to control. The early killing of the cover crop makes control easier, reduces the amount of residue to plant into, doesn’t have too much residue that impairs soil dry down and allows for significant decomposition of the ryegrass residue and the release any nitrogen or nutrients to the system. More mature ryegrass may take several years to completely decompose. It is important to not let the ryegrass go to seed or it may create additional control problems in the future.

In corn production, apply 2-3 pints/a of glyphosate with ammonium sulfate and surfactant in early April. At planting time or before emergence, use 1.5-2 pts/a of glyphosate with 1.6- 2#/a. atrazine and other residual chemicals. Princep and Basis Gold have shown good activity on annual ryegrass. After the crop emerges, escapes can be controlled with labeled rates of Accent, Steadfast, Beacon, Option, or Northstar.

In soybean production, it is still recommended that the first spray be done in early April and to use a glyphosate product at the rate of 2-3 pts/a with ammonium sulfate and surfactant. The use of Roundup Ready seed makes controlling escapes much easier. At planting time, the use of a burn down product like glyphosate, Gramoxone plus Sencor, and other products normally gives very good control. Sencor has shown good residual activity on ryegrass. After the crop emerges, escapes can be controlled with Fusion, or Post Plus. Glyphosate can be used in RR soybeans.

Conclusion

The use of annual ryegrass requires good management and timing. It must be seeded on time and it must be sprayed on time. Late planting reduces the effectiveness and amount of soil benefits. Late spraying can result in poor control, more residue that is slow to break down, potential for reduction in subsoil moisture and a negative effect on crop yields and increased costs.

Potential benefits are significant changes in soil properties, improvement in soil conditions to allow greater crop rooting, increased soil tilth and water infiltration, better soil aggregation, and potential for increased crop yields.