Ryegrass

The ryegrass is a perennial herbaceous plant of the Poaceae family. What are the dormancy breaks of ryegrass and the main control levers?

Description

Common names: perennial darnel, English ryegrass, common ryegrass, cheatgrass.

See:

Italian ryegrass
Perennial ryegrass (English ryegrass)

Ryegrass is favored by large-scale cropping systems with short rotations and winter crops.

Its seed production is significant (around 300 to 1500 seeds per plant). Its SDR (seed decay rate) is also quite high: 98% of seeds become unviable for germination after 3 to 5 years.

Italian ryegrass and English ryegrass are two types of forage grasses that mainly differ by their life cycle, growth rate, and primary uses.


	Italian ryegrassLolium multiflorum	English ryegrassLolium perenne
Life cycle	Biennial plant, often grown as an annual, meaning it has a shorter life cycle (one to two years). It is generally sown for a quick harvest.	Perennial plant, which can last several years. This makes it a longer-cycle grass, suitable for permanent pastures.
Growth rate	Fast growth, offering multiple cuts from the first year, making it suitable for short-term crops.	Growth is slower than Italian ryegrass, but it regenerates well after cutting and grazing.
Production	Produces abundant forage with high nutritional value and good dry matter yield.	Although yield is slightly lower than Italian ryegrass, it is valued for its resistance and longevity.
Use	Ideal for temporary pastures and as a green manure, often sown as an intercrop or after a main crop to enrich the soil.	Suitable for permanent pastures and long-term grazing systems. It is a grass that offers good forage quality with stable production over time.

Weed control

Development conditions

Ryegrass is a problematic grass weed in cereal systems. Some factors favor it:

Soil composition: with less than 30% clay (sands, chalks, silts). A real asset is the earthworm anecic type that produces clay from limestone, iron and organic matter.
Structure: poor soil structure (crusting/compaction/regular tillage/possible lack of CaCO3 and/or organic matter). This may be linked to loss of clays, detachment of calcium ions and thus a too low active lime content (not enough carbonates). These factors are reinforced by tillage (which destabilizes soil structure). However, note that no-till favors surface decalcification, a main factor in the disintegration of the clay-humus complex and clays;
Mineral imbalance: ryegrass indicates a problem of insoluble bases (Ca, K, Mg) but generally also a mineral imbalance with K<Mg. The K/Mg ratio can be unbalanced if there is too much potash or not enough Mg. Often, if this ratio is above 2, it favors RG. Micro-plot tests can be tried with 1 bag of gypsum per 100 m², also feasible with magnesium oxide.
An excess of nitrogen in the soil (which can be linked to over-fertilization due to tillage).
Soil conditions (moisture and temperature) and the year's climate. Especially in spring, which can influence dormancy break: dormancy is stronger (grass has more difficulty emerging) if spring has been wet and cool (this is mainly true for black-grass but also for RG).

In the short term, an application of magnesium can be considered to combat the ryegrass problem.

In the longer term, carbonate application will create favorable conditions to facilitate the action of earthworms.

Control levers

Dense Cover crops;
Limited tillage: grasses like ryegrass and black-grass are sensitive to soil disturbance. By avoiding soil disturbance, their emergence is reduced. Thus, seeding speed should be adapted to avoid overworking the soil (6 km/h or less). A seeder suitable for No-till is necessary. Disc seeders are clearly superior to tine seeders in this regard.
- No soil disturbance is the most effective technique against ryegrass seed germination.
- Then, in tillage, plowing is the second most effective, provided it is not repeated within 5 years.
- Then, shallow tillage is the least effective in ryegrass control;
Species diversity in Crop rotations;
Incorporate perennial species in permanent cover (alfalfa/clover/bird's-foot trefoil);
Correct mineral balance with applications of magnesium (dolomite/carbonate/magnesium oxide). It is possible to test within plots by spreading a bag of gypsum (Gypsum=CaSO4) on 100 m² well delimited and a second test with magnesium oxide;
No-till under cover;
Collecting straw chaff at harvest;
Rotation 2-2 (winter-winter/spring-spring);
Delay sowing date, accompanied by a false seedbed, to eliminate an initial emergence,
Chemical control is based on a program combining three active ingredients: flufenacet, prosulfocarb, and chlortoluron. These active ingredients are mainly root-acting and therefore do not require a specific adjuvant. However, they require good soil moisture to be effective and should be applied before grass emergence ideally or at a young stage at minimum.
Resistant ryegrass establishes itself in highly favorable environments, to continue to "correct". A reflection conducted with Brazilian agronomists, based on the hypothesis "nothing better than a grass to fight grasses". Against resistance phenomena of wild ryegrass, sowing a cover of Italian ryegrass can help support the soil during restructuring. To be combined with magnesium carbonate application to raise the level (1 to 2 t/ha). Initial trials showed a risk level decrease from 70 ryegrass/m2 to 35/m2.

Prerequisites

Regulation: the use of Chlortoluron is possible until 02/28 and at the tillering stage of plants. It is also legally prohibited on drained soils and reserved for varieties tolerant to its use.
For good selectivity: it is imperative to have well-buried seed (at least 2 cm) and thus a regular sowing. Heavy rains (>20mm) within 3-4 days after application can increase lack of selectivity.
Compensate losses: it is possibly recommended to increase seeding density to compensate for potential losses related to these (very strong) autumn programs.
Product doses: should be adjusted according to soil types. In heavy soils, higher doses can be used. Lower doses are preferred in free-draining soils.

Sources