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Pasture density reduces the establishment and regeneration of vulpia

A.R. Leys, P.M. Dowling, and B. Plater

Agricultural Research Institute, Wagga Wagga NSW 2650
Agricultural Research and Veterinary Centre, Orange NSW 2800

In recent years vulpia, Vulpia bromoides and V .myuros, has become an increasingly common component of subterranean clover, Trifolium subterraneum, based pastures in southern Australia. A recent survey in southern and central NSW identified the general deterioration of improved pastures as the major factor responsible for the increase in vulpia (Leys and Dowling, unpublished data). Because of this a field experiment was undertaken to investigate the effect of (i) subterranean clover (SC) density, and (ii) a mixture of SC and annual ryegrass (RG), Lolium rigidum, on the establishment, seed production, and regeneration of vulpia.


Four pastures (three SC densities and the SC/RG mixture) were established at Wagga Wagga with two densities of vulpia, V.bromoides, at two soil fertility levels (low = unamended paddock fertility; high = lime and compound fertilizers added so that soil fertility was not limiting SC growth). Low, medium, and high SC densities were obtained by sowing 1, 25, and 100 kg/ha SC cv. Junee in small plots (2 m by 6 m) on 21 May 1990. The SC/RG mixture was established by sowing 25 kg/ha SC plus 20 kg/ha RG.


SC and RG plant densities which had established by August 1990 were: low SC, 142 plants/m2; medium SC, 496 plants/m2; high SC, 1,846 plants/m2; SC + RG, 677 + 708 plants/m2. Averaged over vulpia densities and fertility levels, the medium and high SC densities reduced vulpia dry weight in October 1990 by 50 and 77%, respectively, when compared to the low density. The same treatments reduced vulpia seed production in November 1991, by 51 and 77%, respectively. The mixed SC/RG pasture reduced vulpia dry weight and seed production by 80%, when compared with the low SC density. Reductions in vulpia were generally greater in the high fertility treatments, and these differences are likely to increase with time.


These results support our contention that the growth and seed production of vulpia can be dramatically reduced by competitive pastures. Wintercleaning with simazine, or spraytopping in the spring, are also very effective for the control of vulpia, and an integrated management system utilising competitive pastures, livestock, and the judicious use of herbicides, is the key to long-term control of vulpia.


This project was supported by a grant from the Wool Research and Development Corporation.

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