Wimmera/Annual ryegrass

Wimmera/Annual ryegrass

Scientific name

Lolium rigidum

Strengths

• Vigorous growth.

• Drought tolerant.

• Tolerant of continuous grazing, heavy stocking, low soil fertility and some insect pests.

Limitations

• Can cause Annual ryegrass toxicity.

• Can be a serious weed in field crops.

Plant description

Plant:

A freely seeding, self-regenerating annual tussock grass. Strains highly variable re time of flowering, habit and tillering; habit varies from prostrate to erect. Fibrous root system. Flowers ~ mid October. Late types may be densely tillered, sprawling when mature.

Stem:

Up to 1 m high, red-purple colour at base extends upwards as plant matures; bent at nodes.

Leaves:

Rolled in bud; dark green, hairless, flat; lower surface shiny and smooth; >2mm wide.

Seedhead:

A spike up to 300 mm long; spikelets edge-on to the rachis and have 10-12 florets, latterly flattened.

Seeds:

Flatter and wider than other ryegrass spp. ~460,000/kg.

Pasture type and use

A productive, nutritious feed, it is well suited to a short term pasture phase in the wheat sheep zone. Tends to decline after a few years pasture and maybe replaced by barley grass/brome grasses. Useful for hay and for improving the productivity of saline land.

Where it grows

Rainfall

360 - 635 mm (>250 mm in WA).

Soils

Suits a wide range of soils. Thrives on high fertility soil and on low-lying “crabhole” country in the Wimmera region, VIC., where rainfall 380-510 mm. Tolerant of moderately saline conditions.

Temperature

Adapted to areas S of 30°S latitude.

Establishment

Companion species

Legumes: sub. Clover, annual medics, lucerne.

Sowing/planting rates as single species

1-3 kg/ha.

Sowing/planting rates in mixtures

0.5-1 kg/ha.

Sowing time

March/April.

Inoculation

Not applicable.

Fertiliser

Correct any nutrient deficiencies, especially N, P.

Management

Maintenance fertliser

For optimum growth Olsen soil P > 15; but tolerates low fertility.

Grazing/cutting

Cool season growth is maximised by autumn deferred grazing. Prolific growth in spring; remains edible during the seedhead phase and is valuable as standing hay. Undergrazing leads to dense population and a heavy demand on soil moisture; this weakens the stand. Phosphate fertilizer to encourage a legume contribution and grazing heavily in spring sustains a ryegrass legume pasture. Makes excellent hay/silage when grown with annual legumes.

Seed production

Seeds freely; matures rapidly in drought conditions.

Ability to spread

Will spread from seed.

Weed potential

A serious, vigorous weed in crops; seed is stimulated to germinate following cultivation. Seed retained well in hay.

Major pests

No information.

Major diseases

Relatively resistant to root-rotting organisms.

Herbicide susceptibility

Propyzamide, Glyphosate. Some varieties have developed herbicide resistance.

Animal production

Feeding value

High.

Palatability

Good, including seedhead.

Production potential

Reasonable winter growth; good spring growth.

Livestock disorders/toxicity

Main host of organisms causing annual ryegrass toxicity, a serious neurotoxic disorder often with fatal outcomes. Both hay and pasture may be toxic.

Cultivars

Group	Cultivar	Seed source/Information
Cultivars non-resistant to ARGT	“Wimmera” - actually a highly variable ecotype	AusWest Seeds
	Merriden	WA
Cultivars resistant to ARGT causing nematode, Anguina funesta	Safeguard	Valley Seeds
	Guard	AusWest Seeds

Denotes that this variety is protected by Plant Breeder’s Rights Australia

Author and date

K. Reed

September 2008