Source: landwirt.com
The hybrid ryegrass (Lolium boucheanum) has become a problem in some grassland regions. It is not winter hardy and is essentially a forage crop.
Hybrid ryegrass is only suitable for intensive field forage production, where it can produce yields of 150 dt dry matter and more. It can form strong clumps that grow up to one meter tall. However, it is undesirable in permanent grassland, as it displaces all other grasses, especially during late use.
High reproduction potential
The hybrid ryegrass is a natural cross between German ryegrass (also called English ryegrass) and Italian ryegrass (also called Italian ryegrass).
Compared to Italian ryegrass (Lolium multiflorum), hybrid ryegrass (Lolium hybrid) is somewhat more winter-hardy. Its widespread distribution is not usually due to targeted seeding, but primarily to its high self-seeding capacity.
Hybrid ryegrass is a fast-growing overlying grass with two typical characteristics. It lacks a pronounced winter dormancy, allowing rapid growth in areas exposed to foehn winds and especially in early spring. This puts other grasses with pronounced winter dormancy at a competitive disadvantage. In addition, this overlying grass is highly competitive, which, with appropriate fertilization, will ultimately displace all other grasses (not just the underlying grasses). Furthermore, hybrid ryegrass has a high seed-borne propagation potential.
The grass only achieves a high fodder value when used intensively and very early, with the "bastard" ultimately remaining alone. When using it, the farmer is forced to adapt to its growth rhythm, otherwise it will immediately become overripe.
Due to its origins in the Atlantic climate zone with warm, humid summers and mild winters, hybrid ryegrass has a low winter hardiness. It thrives only in mild climates and does not tolerate compacted soils or south-facing locations well.
After harsh or snowy winters (snow cover for more than three months), it becomes severely weakened, causing it to overwinter, and the stands to initially appear sparse in the spring. However, due to its high seed-bearing potential, it usually regenerates even after overwintering damage.
The main threat of winter damage is snow mold infestation. This is especially true if the hybrid ryegrass grows too tall into the winter, as is often the case after foehn winds in late autumn, when growth spurts are still present. The resulting gaps are then usually filled with dandelions, common meadow grass, creeping buttercup, or white clover.
Prefer cocksfoot or perennial ryegrass
In permanent grassland, hybrid ryegrass tolerates no competition. Furthermore, due to its rapid growth, hybrid ryegrass ages quickly, meaning it lacks flexibility in use. In terms of harvesting time, it's essentially a "minute grass." If the optimal mowing time cannot be met due to weather conditions, the hybrid quickly begins flowering and then quickly becomes woody.
For intensive use of permanent grassland, perennial ryegrass should be preferred, as it is less competitive as an undergrass and is less susceptible to winter damage. Furthermore, most varieties are turf-forming, forming a dense turf, especially when grazed.
In harsher or drier locations, cocksfoot (late varieties) has also proven very effective as a leader grass. It is less nitrogen-demanding and can also tolerate four to five uses. If the location is too moist for cocksfoot, meadow foxtail should be encouraged as a leader grass instead of cocksfoot. Meadow foxtail forms turf and tolerates frequent mowing, but is a pure mowing grass and only of limited suitability for grazing. Furthermore, it is the first of all grasses to flower and becomes woody very quickly in spring. Therefore, the first growth should be used in a timely manner so that subsequent growth develops sufficient leaf mass.
Therefore, only a single-grass cut or silage cut is possible in spring. Generally, it is important to ensure that grassland mixtures do not contain hybrid ryegrass (even in overseeding mixtures). Invasion through seed dispersal can only be prevented or mitigated by dense turf. Once hybrid ryegrass has taken root, it will repeatedly attempt to establish itself through its intensive seed production. In favorable locations, intensification by using it five or six times before flowering is conceivable in order to exploit the yield potential. Together with Ladino white clover, this would essentially be a type of field forage crop. However, since hybrid ryegrass can only develop its yield potential with intensive fertilization and early use, it is often considered a nuisance weed on farms with medium use intensity, contributing to the development of unstable grassland.
Combating it is difficult
Direct control of hybrid ryegrass is difficult and only possible with the Rotowiper stripping method using glyphosate (e.g., Roundup Ultra). Immediate reseeding is required to fill the gaps. In favorable locations, perennial ryegrass (early, mid, and late varieties) and possibly late cocksfoot varieties, as well as some white clover (tall varieties), should be reseed. For this purpose, reseeding mixtures with a strong emphasis on ryegrass or cocksfoot, for example, are recommended. The variety descriptions should be followed.
Another option would be reseeding, possibly using a reversible rotary harrow. This creates an ideal seedbed and prevents dead soil from being brought to the surface. The competing seed potential, which is primarily contained in the top 2 cm of soil, is largely buried. Reseeding also offers the opportunity to re-establish the weakly competitive meadow grass as the most important undergrass. Separate sowing (sowing the meadow grass first, followed by the remaining seed 14 days later) has proven effective. A fine-crumbly seedbed and rolling the seed with a profile roller are important.
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