It is common to overseed Couch grass with perennial ryegrass to improve its appearance, increase its wear tolerance and to protect the grass once it enters dormancy. The idea is to maintain this grass cover over the cool season months, and then remove it once temperatures begin to increase in the Spring. This then allows the underlying couch to grow.
Improvements in perennial ryegrass breeding have led to ryegrass becoming much more heat tolerant and so it tends to hang on once temperatures increase. This has meant getting a smooth transition has become Increasingly problematic. This is a concern as couch requires around 100 days without ryegrass competition to achieve maximum performance.
This residual ryegrass can often be seen as clumps of ryegrass over the playing surface.
In recent years chemical management has become accepted practice and issues associated with ‘’clumpy ryegrass’’ have increased correspondingly. A herbicide application in early Spring should provide nearly 100% control of the overseeded perennial ryegrass within 21 days after treatment, but the same chemical options applied to clumpy ryegrass often only gives 50-60% control.
The speed of transition using chemicals also plays a role in deciding when to apply these. A faster acting chemical can be applied later into the Spring, whilst slower options like Kerb, (which takes up 8 weeks to work) you apply much earlier in the season.
Herbicides from slowest to fastest removal of perennial ryegrass: Kerb, Tribute Selective, Coliseum, and Recondo Herbicide which is a Monument Herbicice alternative.
