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COMPETITION BETWEEN RAMPION MIGNONETTE (RESEDA PHYTEUMA L.) AND WHEAT, BEANS, FESCUE AND SUBTERRANEAN CLOVER

R.S. St John-Sweeting, H.A. Reimers and E.D. Carter

The University of Adelaide, Department of Agronomy and Farming Systems, Roseworthy SA 5371

Abstract

Rampion mignonette (Reseda phyteuma L.) is a new weed to South Australia, being first found in vineyards at Clare in 1986. A replicated split plot factorial trial was conducted to ascertain the competitive effects between rampion mignonette and wheat, faba beans, subterranean clover and grass pasture. The results of the trial indicated that rampion mignonette is primarily a weed of bare ground and so is unlikely to become a major weed of broadacre crops and pastures in the South Australian dryland farming system.

Keywords: Competition, Crops, Pastures, Weeds, Rampion mignonette and Reseda Phyteuma.

Four species of Reseda existed in South Australia, R. luteola, R. alba, R. lutea, and R. odorata until the discovery of Reseda phyteuma at Clare in 1986 (5). Other than a temporary outbreak at Nagambie, Victoria in the mid 1980?s the outbreak at Clare is the only other known occurrence of rampion mignonette to have occurred in Australia (1). In 1990, it was estimated to have colonised 38 ha of vineyards (2). The aim of this study was to ascertain the potential of rampion mignonette to compete with wheat, faba beans, subterranean clover and grass pasture of the South Australian dryland farming system.

Methods

The trial site was located 2 km East of Clare, (150 km North of Adelaide, South Australia) on crusty red duplex soils with surface gravel in an area with a mean annual rainfall of 659 mm, predominantly of winter incidence. The trial was conducted in a pasture paddock adjacent to vineyards which had previously been grazed by sheep and horses and was known to have had an even cover of rampion mignonette. The site was fenced to exclude grazing animals and rotary hoed on 3 June, 1992 to incorporate vegetable matter and mignonette seed and to produce an even and friable seed bed.. The trial was a split plot design where the factor plants (wheat, bean, clover and grass) were randomly assigned to the whole plots and the factor treatments were randomly allocated to the subplots. The trial was replicated six times. Each replicate contained four plots, two crop and two pasture. The two crops were wheat, Triticum aestivum L., `Machette and faba beans, Vicia faba L., `Fiord . The two pastures were subterranean clover, Trifolium brachycalycinum L., `Clare and tall fescue, Festuca arundinacea L., `Demeter . Twenty six main plots 1.7 m wide and 10 m long were sown on 17 June, 1992 using a Connor Shea three point linkage ten tyne drill with 15 cm row spacings. The wheat, faba beans, subterranean clover and tall fescue were drilled to 5 cm, 5 cm, 1 cm and 1 cm depth and sown at 60 kg/ha, 150 kg/ha, 20 kg/ha and 18 kg/ha respectively. Buffer plots of wheat were sown at each end of the trial. After emergence, four fixed 0.5 m2 quadrats were randomly located in each plot. The quadrats were aligned 1 m along the rows and 0.5 m across the rows containing three sown rows. The wheat, beans, clover, grass and other weeds were hand weeded from the assigned fixed quadrats on the 28 July, 29 September and 20 October, 1992. Other weeds were hand weeded from assigned fixed quadrats on the 18 August, 8 September, 20 October and 11 November, 1992. Rampion mignonette seedlings were counted on the 2 December, 1992. Data was analysed by two way analysis of variance using Excel 5.

Results and discussion

Table 1. shows the establishment level of rampion mignonette seedlings on the 2 December, 1992. These results indicate that rampion mignonette is a poor competitor with winter annuals and is a weed of disturbed bare ground. The removal of weeds may also affect subsequent germinations however the weeded crop or pasture areas, where crop and pasture remained, did not show increased germinations levels. Increased germinations on bare soil may be due to higher soil moisture and temperature levels. Light and CO2 in the soil may also be affected by the bare surface conditions.

Table 1. Mean number of rampion mignonette seedlings / m2 at 2 December, 1992.

TREATMENT

Crop
Wheat

Crop
Bean

Pasture
Clover

Pasture
Grass

Crop or Pasture
with rampion mignonette*
and no other weeds (weeded).

0

0

0

0

Crop or Pasture
without rampion mignonette
and no other weeds (weeded).

0

0

0

0

Bare fallow ground with the
Crop or Pasture removed,
with rampion mignonette
and no other weeds (weeded).

100 a

84 ab

64 bc

47 c

Crop or Pasture
with rampion mignonette *
and other weeds (mainly ryegrass).

0

0

0

0

* Rampion mignonette did not establish in these plots.
Means followed by different letters are significantly different. l.s.d. = 23 (P=0.05).

This supports findings reported from the Crdoba region of Spain where rampion mignonette is regarded as a summer weed germinating in spring and growing through the summer and mainly infests bare ground between sunflowers (4) and that rampion mignonette mainly grows in olive groves in the south of Spain and not in annual crops (L. Garcia-Torres, pers. comm.). In Europe, it is found mainly in vegetable crops, more rarely in cereals and on wasteland (3).

Conclusions

The results indicate that rampion mignonette is a weed which colonises bare ground. Rampion mignonette did not establish under growing winter annuals and so therefore is unlikely to have potential to become a major weed of broadacre crops and pastures in the South Australian Dryland Farming System. Rampion mignonette has the potential to compete with grapevines and reduce grape yields because it is common practice to maintain bare ground under grapevines during the late spring and summer.

Acknowledgments

We thank members of the Wine Industry particularly Jim Barry Wines and gratefully acknowledge the support, both financial and in kind of the South Australian Animal and Plant Control Commission, the former National Key Centre for Dryland Farming and staff of I.A.M.A.

References

1. Carter, R.J. 1993. Proc. 10th Aust. and 14th Asian-Pacific Weed Conf. Melbourne. pp. 505-509.

2. Cooke, D.A. 1991. The Sth Aust. Naturalist. 65, 62-63.

3. Hanf, M. 1984. In: The Arable Weeds of Europe with their seedlings and seeds. BASF Ltd, London.

4. Hidalgo, B., Saavedra, M. and Garcia-Torres, L. 1990. Weed Res. 30, 309-318.

5. St. John-Sweeting, R.S., Carter, R.J. and Reimers, H.A. 1992. Proc. 6th Aust. Agron. Conf.
Armidale, p.603.

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