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Siratro
(Macroptilium atropurpureum)

Sirato - illustration  
  • perennial twining legume
  • for wide range of reasonable soils
  • combines with tall grasses
  • not tolerant of constant heavy grazing
  • easily frosted
  • susceptible to leaf diseases.

Macroptilium atropurpureum (DC) Urban - 1 flowering and fruiting vine; 2 flower; 3 seed.

Siratro grows well in moist, subtropical or tropical climates with 800-l,500 mm rainfall, and on a wide range of reasonably drained soils. It grows best in summer and early autumn, being slower than the desmodiums or glycine in the spring. Its leaf is burnt by light frost, while more severe frosts will kill the plant back to the crowns.

It has persisted well under dry conditions and under moderate grazing pressure due to its deep and well developed root system.

Whilst very successful when superphosphate was cheap, Siratro has now lost favour to the less demanding legumes such as the stylos. However, it remains a highly productive species able to fix large amounts of nitrogen and pass this quickly to the companion grasses.

Siratro is moderately resistant to reasonable grazing pressure once well established. Although it declines under constant heavy grazing, it can persist if occasionally spelled to seed in autumn. This helps to maintain soil seed reserves necessary for natural seedling regeneration.

Siratro establishes readily from seed and plant nodulates well with native rhizobium.

Bean fly can attack late-planted seedlings unless seed is treated. Its susceptibility to halo blight limits its use in areas with certified bean seed production, while in higher rainfall areas, siratro is devastated by leaf blight.

Because leaf rust has become a serious problem, reducing yields markedly, a rust-resistant siratro, cv. Aztec, has been released.

Aztec siratro is worth planting in legume mixtures with stylos and Wynn cassia on better soils.

Creator: Ian Partridge
Date created: 07 April 1998  Revised: 15 January 2003
 

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