Problems in controlling Italian Rye-grass tend to be more restricted to specific areas compared with the more widespread problems with Black-grass.
Particular ‘hot spots’ include Essex, Kent & Yorkshire. The reasons for increasing problems with rye-grass are:
- Rye-grass has been widely sown in the past for grazing or conservation and those old sown populations have almost certainly given rise to the current infestations in arable crops. Sowing rye-grass for amenity purposes (e.g. conservation headlands) may pose similar risks.
- Increase in autumn sown crops, especially cereals and oilseed rape, which greatly favour rye-grass due to its early autumn emergence pattern.
- Earlier autumn sowing – in 1975 only 5% of winter wheat was sown in September; in recent years this proportion has increased to 50%.
- Herbicide resistance – resistant rye-grass is widespread (in 33 counties) although the impact tends to be less pronounced than with black-grass. Cases of severe resistance do occur and are likely to increase.