Greenleaf desmodium

Greenleaf desmodium
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NOTE: The information in this Agnote must be read in conjunction with Introduction to selecting and using pastures in NSW, which covers information on areas of adaptation, sources of variability, species mixtures, and important issues related to animal health and the conservation of native vegetation.

Pasture type and use	Viny, creeping, twining and climbing spring/summer/autumn producing tropical legume for grazing.
Area of adaptation	Moist subtropical north coast, on fertile deeper well-drained soil out of reach of heavy frost.
Min. average annual rainfall	1100 mm (summer-dominant), Far North Coast.
Advantages	Its climbing habit and vigorous warm-season growth helps it to smother weeds. Combines well with tall-growing tropical grasses and other twining tropical legumes to build up a big bulk of high-quality feed, which can be used by cattle in the warmer months. Used as stand-over feed to help fill a late autumn/winter feed gap.
Disadvantages	Not as hardy as atro; requires soils that are more fertile with good moisture-holding characteristics. Succumbs to continuous heavy grazing. Slower to establish than most other viny tropical legumes. Twining and climbing habit could compete with native species in some situations.
Soil requirements	Does best on fertile well-drained soils that have adequate depth and moisture-holding capacity. It can tolerate acid soils that have a pH(Ca) down to around 4.5.
Varieties	Greenleaf
Sowing rates:	as only species Rarely sown alone. in mixtures - 0.5–1 kg/ha is usually adequate in a mix with more than three other species, but can be sown at up to 2 kg/ha if the cost is not too high.
Sowing time	October to January is best, but try to avoid hot, dry summer spells.
Companion species	Usually sown on warm hill sites with other twining tropical legumes (atro, glycine and axillaris) and grasses such as setaria, Rhodes grass and green panic.
Inoculation	Special inoculum for Desmodium intortum.
Major nutrient deficiencies	Varies with soil type, but phosphorus, sulfur and molybdenum are the most likely nutrients to be required.
Main insect pests	Amnemus weevil larvae can damage roots.
Main diseases	Greenleaf desmodium has some resistance to legume little leaf and root knot nematode.
Management	Seedling growth is slow and initial grazing should be light, aiming only to prevent grass dominance. It is susceptible to overgrazing, and needs sufficient spelling from heavy grazing. Do not graze too severely, so that there is plenty of vine and some leaf remaining to allow good regrowth. The more leaf left on the plant, the faster the regrowth. Aim to retain at least 15 cm height of material in order to achieve maximum production and persistence.
Livestock disorders of particular note	No livestock disorders encountered.
Additional tips	To ensure successful establishment, competition from existing species must be eliminated and seed sown no deeper than 10 mm with good soil/seed contact. Rolling will assist. (One pass with a large off-set disc is a common method of seedbed preparation.) Erosion risk is less if a registered herbicide and ‘reduced cultivation’ techniques are used. It is not suited to oversowing into existing swards. Germination of machine-harvested seed is usually adequate due to scarification during harvesting and cleaning.
Further information	Cameron, DG 1984, ‘Desmodiums’, Queensland Agricultural Journal, Sept.–Oct. 1984, Queensland Department of Primary Industries.

Acknowledgments

Advice on livestock health disorders was provided by Dr Chris Bourke, Principal Research Scientist, NSW Agriculture, Orange. His contribution is gratefully acknowledged.

Photo: Warren McDonald, Former Technical Specialist (Pastures), NSW Agriculture, Tamworth