Lolium temulentum (Darnel Ryegrass)

Scientific name

Lolium temulentum  L.

Synonyms

Lolium temulentum Bertero ex Steud.

Common names

Darnel ryegrass, darnel, poison ryegrass

Family

Poaceae (Gramineae)

Origin

Countries in the Mediterranean region.

Naturalised distribution (global)

Lolium temulentum is widely naturalised in the subtropics and temperate regions of many countries in the world.

Introduced, naturalised or invasive in East Africa

Lolium temulentum usually grows in the same production zones as wheat and is considered a weed. In Kenya, it has been recorded in the wheat growing areas of Rift Valley, Narok. In Tanzania it has been recorded in Morogoro.

Habitat

Lolium temulentum infests wheat fields and other cultivated land.

Description

Lolium temulentum is a weedy annual grass. The plant stem can grow up to 1 meter tall. The flower is a large panicle ("ears"). The ears are light and upright and mature ones are black in colour.

Reproduction and dispersal

Lolium temulentum spreads as a contaminant of wheat seed, by people and by farm animals.

Similar species

The similarity between wheat and Lolium temulentum is so great that in some regions L. temulentum is referred to as true wheat (Triticum species). L. temulentum and wheat look alike until the ear appears and are distinguished as follows:

  • The ears on the real wheat are so heavy that it makes the entire plant droop downward, but L. temulentum, whose ears are light, stands up straight.
  • Wheat ripens to a brown colour, whereas L. temulentum turns black.
  • When L. temulentum matures, the spikelets turn edge ways to the rachis whereas the wheat spikelets remain as they grew previously.

Economic and other uses

Lolium temulentum grass can be used for fodder and for erosion control. However, these uses cannot compensate for this plant's overall negative impacts.

Environmental and other impacts

Lolium temulentum is a weed of wheat farmlands. Even a few grains of this plant will adversely affect crop quality. Its seeds are poisonous to people and livestock. It is very difficult to separate the seeds of L. temulentum from those of what and other small grain crops as they are similar in size and weight. L. temulentum can be a host to a variety of crop pests and diseases.

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Preventive measures such as sewing clean seed and preventing seed formation are important means of management. Hand weeding can control this species although this is difficult to undertake early because of the resemblance between this weed and the infested wheat crops. Chemical control is possible in barley and other crops from which it is easy to distinguish. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Biological control method unlikely to be investigated because of the fact that this species is closely related to valuable, forage grasses.

Legislation

Lolium temulentum has been declared a noxious weed in Kenya under the Suppression of Noxious Weeds Act (CAP 325). Under this act the Minister of Agriculture, can compel land owners who have such declared noxious weeds growing on their land to remove or have it otherwise removed. However, this species is not declared in Uganda and Tanzania.

Notes

In the New testament, in the parable of the Tares in the Gospel of Matthew: "Let both grow together until the harvest: and in the time of harvest I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them: but gather the wheat into my barn".

Lolium temulentum is also said to be one of the many ingredients in Mithradate, which is supposed to have been used by Mithridates VI on a daily basis to render him immune to poisoning.

References

CABI Invasive Species Compendium online data sheet. Lolium temulentum (darnel). CABI Publishing 2011. www.cabi.org/ISC. Accessed March 2011.

Government of Kenya (1983). The Suppression of Noxious Weeds Act: CAP 325 of the Laws of Kenya. 2nd Ed. Government Printer, Nairobi, 5 pp.

Schardl, C.L., Grossman R.B., Nagabhyru P., Faulkner J.R. and Mallik U.P. (2007). Loline alkaloids: currencies of mutualism. Phytochemistry 68 (7): 980-996.

USDA Plants Profile. Lolium temulentum. The Plants Database. plants.usda.gov/java/profile. National Plant Data Center, National Resources Conservation Service, United States Department of Agriculture, Baton Rouge, Louisiana, USA. Accessed January 2011.

Wikipedia contributors. "Lolium temulentum." Wikipedia, The Free Encyclopedia. Accessed January 2011.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke