African love grass (Eragrostis curvula)

Alan Broughton

African love grass, a native of eastern Africa between Tanzania and the Cape of Good Hope, is a serious weed extending from South Australia to Queensland. It quickly colonises infertile acidic sandy soils and can form pure stands. It is a perennial grass, dormant in winter and only palatable to livestock in spring before it starts sending up flower spikes. Seeds are viable for up to 20 years, but the young seedlings are poor competitors, and establishment is dependent on the absence of other plants. Overgrazing is a prime factor in its development.

In some regions it has been declared a prohibited weed, which means landholders are obliged to take steps to eliminate it. However methods often advocated by control officers are counter productive. Spraying with herbicides kills the plants but creates the perfect seedbed for mass germination of seedlings, with the result that farmers can spend huge amounts on herbicides with no long term advantage.

The best control method is prevention. Seeds are spread in hay purchased from an infected property, by the movement of vehicles (roadside mowing has quickly extended affected areas), and by animals via dung, coats and feet. In the absence of these spreading methods new seedlings are generally restricted to the immediate surrounds of established plants. Of utmost importance in vulnerable soils is livestock management – a sound rotation policy that allows pastures to recover after grazing leaving no bare patches will produce a dense pasture that helps keep African love grass out. When infestations are small each plant can be dug out as soon as it is noticed – the plants are quite distinctive when the flower heads appear and easily seen. Plants should not be permitted to set seed. Removal requires monitoring between November and April each year, at least once a month, in order to be successful. In sub tropical areas the season is extended.

For large well-established colonies the following control program can be used. It is advisable to experiment on a small scale to monitor the results. Once a control program has been decided upon it should be carried through fully, otherwise the expenditure will be wasted.

• Remove livestock as they will eat out all the competition
• Fertilise the soil according to the results of a soil test; commonly lime and phosphorus are needed
• Burn the patch in autumn or winter, as soon as fire restrictions have ended and the tussocks have enough flammable material
• Direct drill a dense crop of oats or cereal rye with subterranean clover; tall varieties are preferable to create more shade
• Slash the crop at maturity to create a thick mulch (if desired the crop can be headed first, but if left the seed drop will germinate again in the autumn)
• Consider direct drilling a summer crop of brassicas, sorghum or millet into the mulch
• If the tussocks are still alive, consider ploughing them and the summer crop in as a green manure and sowing oats or rye again in the autumn.

Severe infestations in areas where African love grass is no longer declared a prohibited weed are best managed as pastures. The grass sustains large herds of wild animals in Africa. There are some important management practices that can make good use of the weed and eventually lead to its decline.

Fertilise the land with minerals (lime, rock phosphate, trace elements) or biological products (compost, worm castings). This will increase the palatability and nutrition of African love grass, and at the same time increase the ability of other species to compete. Some researchers have found this to be very effective.

Keep African love grass young. It may be advantageous to burn the mature patches in autumn or winter to create fresh growth in spring. Graze before flower heads are produced with large numbers of animals over a few days; repeat the grazing several times over summer to prevent seed setting. If the grass gets away it can be slashed, unless the seed is mature.

Remove stock during the African love grass dormant season (generally from mid autumn to mid spring) to allow winter grasses to establish.

Rotational grazing is essential, otherwise stock will remove all the competition.

Goats are very effective at control. They are the only animals that eat the mature plants, including the seedheads. The viability of the seeds is destroyed in the digestive system, in contrast to the case with other animals.

This African love grass management strategy can be used for other unpalatable perennial grass weeds such as serrated tussock, rat’s tail grass (Sporobolus indicus), spear grass and wire grass (Aristida species). The often recommended hard grazing method is counter productive, as it completely eliminates competition. With all such weeds the most successful control method is to create favourable conditions for the better grasses rather than to attack the weed.

A useful resource with various control options is African Lovegrass – Interim Best Practice Manual, published by East Gippsland Landcare Network, edited by Darren Williams.