Sphere medic

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 This is an acid-soil-tolerant annual medic of mid-season maturity. Because of its rooting system it has the potential to yield later into spring than many other annual legume species.
Area of adaptation Areas of the Central West Slopes and Plains, Southern Slopes and Riverina where soils have become too acid for barrel medics to successfully nodulate and fix nitrogen.
Min. average annual rainfall 350 mm (winter-dominant rainfall).
Advantages
  • Tolerates acid soils (although not as tolerant as murex medic).
  • Tolerates redlegged earth mite.
  • More indeterminate in flowering (can stay green longer than other annual legumes with a similar flowering time).
  • Large-seeded; large cotyledons; excellent seedling growth.
  • Excellent winter production.
  • Good tolerance of the foliar diseases that normally affect sub clover.
  • Good tolerance of Phytophthora root rot.
Disadvantages
  • Susceptible to bluegreen aphid.
  • Will not tolerate waterlogging.
  • Germination is impaired under deep residues of dry material.
  • Hard-seed content is too high to sow as a monoculture.
Soil requirements Suits pH(Ca) range 4.8–8.0. It is not suited to deep sands or poorly drained areas.
Varieties Orion
Sowing rates:
- as only species 8 kg/ha
- in mixtures 4–5 kg/ha
Sowing time Autumn
Companion species Use with subterranean clover on suitable soils where cropping is a regular part of the rotation. Use murex medic and sub clover where adequate rainfall allows the introduction of murex.
Inoculation Inoculate seed with group AM inoculant.
Major nutrient deficiencies As for all medics, requires adequate levels of available phosphorus. Sulfur levels should also be monitored.
Main insect pests At the seedling stage, sphere medic tolerates redlegged earth mite — it is more tolerant of redlegged earth mite than any current sub clover or barrel medic. However, redlegged earth mite may still attack the flowering medic in spring and cause flower abortion and seed-set reductions.

Orion has not been bred for resistance to bluegreen aphid and has similar susceptibility to that of the medic varieties Santiago and Jemalong.

Main diseases Orion is resistant to spring blackstem (Phoma medicaginis).
Management This species has large seeds and needs higher seeding rates than some other medics. Light grazing can commence after the 5–6 true-leaf stage. It can be grazed hard in winter without detrimental effects.

Hard grazing post-flowering will reduce seed yields. Grazing needs to be carefully controlled. The large pods are in an accessible position on the soil surface and are attractive to sheep. Large quantities are readily eaten and do not escape digestion.

A light incorporation of pods into the soil can reduce ‘pod theft’ by stock and assist in breaking down hardseededness.

Livestock disorders of particular note Can cause bloat in cattle.
Additional tips Orion is particularly sensitive to herbicides containing MCPA.
Further information

Acknowledgments

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

Photo: Mary-Anne Lattimore, NSW Agriculture, Yanco.