The ecology and management of the "take-all" weed Polymeria longifolia (Peak Downs curse) in cotton

Project Aims
Background
Research Undertaken
Research Proposed
Research Publications
Researchers
Project Support

Project Aims

This PhD research has four broad aims. These were:

1. To survey the distribution, spread and potential control of P. longifolia by a mail survey and to establish its relationship to crop management practises, soil type and seasonal conditions.

2. To quantify the competitive impact of P. longifolia growth on cotton yield.

3. To examine the biology and ecology of P. longifolia

This was undertaken by investigating the phenology of the plants
e.g. emergence, vegetative and reproductive growth;
the role of seeds and rhizomes in reproduction and spread;
seed germination and dormancy;
the influence of rhizome size on regrowth and,
the influence of defoliation, water and nitrogen application
on the regrowth of glasshouse and field populations of P. longifolia

4. To elucidate the principles for controlling P. longifolia based on an understanding of the weaknesses of the weed and other aspects of its ecology.

Background

Weed control costs the Australian cotton industry $50 million annually. One of the most competitive and difficult to control weeds, which is likely to become more serious under current management practises is P. longifolia . It belongs to the 'take-all' group of weeds, so named because of their perennial, rhizomatous habit and ability to smother the ground and take all the nutrient and water resources available in the soil. Although ranked as one of the ten major weeds of cotton, virtually nothing is known about its ecology or how best to control it.

Research Undertaken

Research for the above aims was undertaken in the 1996/97 and 1997/98 cotton growing seasons and concludes with limited trial work this season (1998/99). This included the following points which have been numbered to correspond to the aims above.

1. The completion of analysis of mail survey results has occurred. A draft chapter of the mail survey has been prepared.

2. An investigation into the competitive impact of P. longifolia on cotton is now complete. This trial was conducted over the two seasons 1996/97 and 1997/98. The data from this trial awaits analysis.

3a. Two seasons of life cycle studies have been completed in the field. These were conducted at two sites at two locations (Colly Farms Ltd., Collarenebri and Auscott Ltd., Moree) over the1996/97 and 1997/98 cotton growing seasons. These trials have established baseline biological data for the plant e.g. phenology, density, dry weight, flowering, seed production, seedling emergence and patch size change. The analysis of data from these trials is under way.

b. The modes of reproduction have been investigated in two glasshouse trials with another seed germination trial continuing. The analysis of data from these trials is under way.

c. An experiment to determine the water and soil nutrient use of P. longifolia was conducted over the 1997/98 season. Processing of the data is continuing.

d. Observations on the phenology of P. longifolia in uncultivated areas have been made since October 1997 and will continue through this season. Data analysis is under way. These populations will be compared to 'in field' areas in an effort to determine the factors that favour the growth of P. longifolia

4. Two field experiments to determine the affect of herbicide application on P. longifolia growth and cotton yield were conducted during the 1997/98 seasons. Processing of the data from the defoliation trial conducted in 1996/97 is continuing.

Research Proposed

A field experiment to determine the factors that favour the growth of P. longifolia in an uncultivated area has been initiated and is continuing. These factors are defoliation, water and nitrogen application.
A glasshouse trial to determine the affect of these factors on glasshouse grown P. longifolia has been planned and will be conducted this season.
A trial to determine the affect of herbicide application on rhizome and shoot growth has been planned and will be conducted this season.

These trials will allow observations on the rhizome growth of P. longifolia, an area needed to 'round out' the thesis. They will also help in elucidating the principles for management of P. longifolia.

Research Publications

A partial summary of the results has been recently published in The Australian Cottongrower, September-October 1998 issue, pp. 37-43. and the Proceedings of the 1998 Australian Cotton Conference, pp. 187-192. A poster outlining some results of my thesis was presented at the 1998 Australian Cotton Conference.

Researchers

Assoc. Prof. Brian Sindel (Project Leader) Senior Lecturer in Weed Science Division of Agronomy and Soil Science School of Rural Science and Natural Resources University of New England Armidale NSW 2351	Telephone: (02) 6773 3747 Fax: (02) 6773 3238 Email: bsindel@une.edu.au
Stephen Johnson (PhD Student) Division of Agronomy and Soil Science School of Rural Science and Natural Resources University of New England Armidale NSW 2351	Telephone: (02) 6773 2196 Fax: (02) 6773 3238 Email: sjohnson@une.edu.au
Assoc. Prof. Robin Jessop (Co-supervisor) Assoc. Prof. in Crop production Division of Agronomy and Soil Science School of Rural Science and Natural Resources University of New England Armidale NSW 2351	Telephone: (02) 6773 2505 Fax: (02) 6773 3238 Email: rjessop@une.edu.au

Project Support

This research was funded by the Cotton Research and Development Corporation (CRDC).

The project was based at the Division of Agronomy and Soil Science , University of New England, Armidale, NSW and involved collaboration with Colly Farms Ltd., Collarenebri, Auscott Ltd., Moree and researchers at the Australian Cotton Research Institute.

Global UNE Links:

Weed Science Group

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