Italian Ryegrass
Italian ryegrass is present on a small number of farms however, growers who have Italian ryegrass have found this weed extremely difficult to control. In farms where it is present it should be treated as seriously as blackgrass as both have similar biology and a high risk of developing herbicide resistance. Italian Ryegrass has:
Figure 1. Italian Ryegrass headed out
Controlling Italian Ryegrass on your farm
- Every farm should employ a zero tolerance policy with Italian ryegrass.
- Careful observation and vigilance around bio-security will allow hand rogueing of any plants (before seed set) entering the farm thus preventing seed return and further populations.
- Where hand rogueing is not possible crop destruction before seed set will prevent seed build up. This area should be taken out of crop production for 4-5 years to eliminate the weed from the field/farm.
Figure 2. Distribution of Italian Ryegrass
Italian Ryegrass Facts
- It has an early autumn emergence pattern, between September and November.
- Seeds have a short dormancy (< 7 years).
- Seed numbers decline rapidly (80% per year) when buried, and seeds do not emerge from >5 cm depth.
- Obligate cross-pollinating – high risk of developing herbicide resistance.
- If left uncontrolled, Italian rye-grass can produce up to 200 seeds but isolated plants up to 1,000 seeds per plant.
- Herbicide resistance is confirmed in Ireland to both ACCase (eg. Axial, Falcon, Stratos Ultra) and ALS (eg. Pacifica, Broadway, Monolith) herbicides
- Suspect herbicide resistance in both wild types and cultivated varieties.
Italian Ryegrass: Identification
- Flattened spike heads with spikelets on their edge arranged alternatively on the opposite side of the stem.
- Short awns on the spikelet.
- Ligule is short (1-2 mm) and blunt.
- Leaves rolled in shoot.
More information on Italian ryegrass identification can be found below:
Figure 3. Italian Ryegrass Identification