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Integration of herbicide and pasture management for long-term control of vulpia

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

NSW Agriculture, Agricultural Research and Veterinary Centre, Orange NSW 2800

NSW Agriculture, Agricultural Research Institute, Wagga Wagga NSW 2650

Vulpia, Vulpia bromoides and V. myuros, is a naturalised winter growing annual grass with many undesirable attributes. In addition to low DM production and poor feed quality, it tends to suppress subterranean clover, Trifolium subterraneum growth and is extremely competitive with newly sown pasture. In recent years it has become a major component of pastures. Vulpia is resistant to the new grass herbicides, but the older chemicals used for winter-cleaning (simazine) and spraytopping (paraquat, glyphosate) have been useful for reducing vulpia incidence in pastures. However, results from both techniques have been disappointing over the longer term. A field experiment was set up to examine the reasons for this by evaluating spraytopping and winter-cleaning at two management levels over a range of environments.


The experiment was conducted at six sites located at Eugowra, Blayney, Bathurst, Beckom, Wagga Wagga and Holbrook. Sites varied in rainfall (450-850 mm AAR), soil texture and pasture composition. All pastures were subterranean clover based and two contained phalaris, Phalaris aquatica (cv. Australian). Four treatments were compared: paraquat, simazine, paraquat plus simazine, and untreated control; each at two levels of pasture management. Paraquat (0.1 kg/ha a.i.) was applied as a spraytopping treatment in the spring of 1989. Simazine (0.63 kg/ha a.i.) was applied in June 1990. The two levels of management were: (i) no amendments; (ii) addition of subterranean clover seed and superphosphate (9.1% P, 11.5% S). The experiment was replicated four times. Treatments were compared by counting plant densities in September 1990.


Averaged over sites and management levels, vulpia seedling numbers on the control plots were 6790/m2. Simazine (78% control) was more effective than spraytopping (46% control) in reducing seedling numbers. However, the results for simazine varied considerably. Where both chemicals were applied, control was increased to 85%.


The effect of management would be expected to increase over the longer term, and preliminary data currently being processed (13 months after simazine application) are indicating that vulpia seedling numbers are decreased on the higher compared to the lower level of management. The results suggest that even for the chemical providing best control (simazine), too many vulpia seedlings remain for the control to be long term in the absence of any other management strategy.


This research is funded by the Wool Research and Development Corporation.

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