Integrated Management Strategies for the Control of Serrated Tussock in Inaccessible Native Pastures

Summary

Background
Control of serrated tussock in native pastures is difficult as they are often located on steep and/or rocky ground with poor soils that make conventional control methods impractical. The main option now available to livestock producers is to manage the native grass infested areas in ways that enhance the competitiveness of existing desirable species. Understanding ways of strengthening native pastures against this disastrous weed is the thrust of this report.
Aims: 
This project aimed to find alternatives to this control practice by investigating which combinations of grazing management, herbicide use and broadcast sowing of pasture species, used in an appropriate sequence, provided the best serrated tussock management through a reduction in serrated tussock seedling establishment and reducing the adult serrated tussock plant herbage mass. 
Findings include:
• Minimising any disturbance that creates niches for seedling recruitment of serrated tussock and which reduces competition from desirable perennial grasses, is the primary requirement for preventing invasion by serrated tussock.
• Defoliation significantly reduced the competitive ability of the native grasses.Microlaena stipoides, found typically on lower slopes, was a more aggressive competitor for serrated tussock than Austrodanthonia spp. common on upper slopes.
• On upper slopes, active grazing tactics (rests to maintain >1.5 t DM ha 1) and the application of herbicide in ways (e.g. spot spraying with fluproponate) that minimise disturbance resulted in the more competitive pastures.
• On the lower slopes, maximum pasture competitiveness was achieved in ungrazed paddocks and paddocks that were actively grazed (rests to maintain >1.5 t DM ha 1) where serrated tussock was spot sprayed with fluproponate.
Conclusions 
Serrated tussock can be controlled, but it takes 3D’s: diligence, deliberation and (minimal) disturbance.  The weed is not the sole focus of a serrated tussock management program; pasture and animal health are of equal importance. Stock type and management need to be considered and this may be relatively simple changes such as reducing mob numbers by combining mobs, or fencing areas off to create more paddocks, to more complex changes such as changing an enterprise from fine wool to fat lambs.