Five trial results detailed in Final Report.

The question is asked - Why grow Pima in A ustraha? There are different answers. The most obvious is the economic consideration, then there is the challenge of doing something new and different. For the sake of this discussion the economic considerations will be outlined. then the management/agronomy of Pima will be compared to Upland and advantages and disadvantages of Pima will be put forward.

Murata Vortex Spinning is a spinning technology of the future. It differs from previous air-jet spinning in that it can spin 100% Upland length cotton at speeds of up to 400 m/min. Furthermore the yarn quality is comparable to ring spun yarn quality. However, to achieve these outputs the fibre must be long and uniform in length. The aim of this project was to evaluate Australian cotton in terms of short fibre and nep content, and how these properties effect spinning on the Murata Vortex Spinner (MVS) in terms of yarn quality and spinning efficiency.

The 1997-98 cropping season in southern Queensland was characterised by a severe, sustained and damaging outbreak of H. armigera. This situation arose as a result of a combination of factors. Helicoverpa attacks most of the crops grown in the Darling Downs agroecosystem, and successive generations can occur where seasonal

conditions are favourable, and control poor, or ineffective. There is a high dependence on insecticides for the management of heliothis in all crops. This over-reliance on insecticides has led to declining efficacy of registered insecticides because of resistance in H. armigera, resulting in more frequent field control failures,increasing pest densities, and increasing costs of control.

The impact of the 1997-98 season on the economic viability of most crops resulted in a widespread realisation within the fanning Ccommunity that a change in the current approach to heliothis management was needed to ensure a farming future in this region. Under greatest threat was the grains industry because it is highly

dependent on 'old' compounds for heliothis management(eg. carbamates). There were also increasing concerns about environmental and human health hazards associated with increasing insecticide use.

In 1998-99 this project was initiated to develop a regional management approach for heliothis on the Downs.

Reflecting the mixed cropping system of the region, the project was jointly funded by the GRDC and CRDC. After consultation with growers, consultants, researchers and funding bodies, two pilot study areas were defined, and a draft strategy developed. The two study areas were on the limbourfloodplain and the other

between Brookstead and CGcilPlains. The Jimbour floodplain area is predonxinantly a dryland grain production region with smaller areas of dryland and irrigated cotton. The Brookstead-CecilPlains area produces predominantly irrigated cotton and grains with smaller areas of dryland grain crops and cotton. Strong local support for the project was expressed at initial grower meetings in each of the areas.

The regional management strategy for H. armigera is based on the theory that it is a local and recycling population of the pest that drives the spring-sumrner build up in pressure. A strategy that targets bottlenecks in the population development will result in a reduction of the overall H armigera population, reducing pest

densities and the frequency with which chemical control are required. Flowing on from the lowered pest pressure and reduced insecticide use would be a reduction in the level of insecticide resistance in the population, and consequently greater opportunity for the use of biological insecticides (eg. Bt and NPV), and other IPM options.

For many years the insect pest management research conducted by the Entomology Team at QDPI Farming Systems Institute, Toowoomba has relied on makeshift spray equipment for the application of pesticides. The investigations carried out included evaluation of biopesticides (Gemstar and Bt), insecticide interactions with beneficials, insecticide efficacy, pest exclusion studies and spray application evaluation. While the various researchers have achieved a great deal with the available equipment, there is scope for safer, more reliable and time efficient methods to conduct much of this research. This is very important as we strive to conduct our research under practical field conditions, and expand our research program related to the development of Best Practice and IPM in cotton. Insect and weeds researchers at ACRI have pioneered the design and construction of two high clearance multi-spray rigs and identified the most appropriate features for this equipment. Our proposal is to draw on the experience gained in the construction of the previous two spray units, and build a third unit for the QDPI Farmimg Systems Institute Toowoomba based research. The spray rig will be light weight and transportable on a tandem trailer so that it can be readily moved to various research locations on the Darling Downs and elsewhere as required.

With the creation of the CRC for Sustainable Cotton Production, weeds

research took focus to the development of sustainable, low input, cotton weed management systems for low weed pressure situations.

Since 1998, Mr Charles has concentrated on the development of a sustainable management strategy for cotton, focussing primarily on nutgrass ecology and management. The nutgrass management strategy that was developed, combined herbicides, cultivation and rotation crops and has shown that a dedicated approach to nutgrass control will allow cotton production and high yields on

nutgrass infested land, while controlling the weed population. The research, on what is considered to be the world's worst weed has resulted in a number of publications and the development of a nutgrass management package, "Controlling nutgrass in Cotton" with CRC support.

The scope of the project has been expanded over the last couple of years. 'The project is now working closely with the CSIRO cotton breeding team, bringing expertise in weed management into the evaluation and development of herbicide tolerant, transgenic cotton varieties. This season the project is working with 2,4-D tolerant, Roundup Ready and BXN (bromoxcynol tolerant) cotton varieties.

In the late 1980s and early 1990s, Verticillium wilt was the most widespread

and important disease of cotton in Australia. The widespread adoption of

CSIRO cultivars with resistance to Verticillium wilt has effectively reduced the

incidence and importance of the disease in recent years'. In California, where

there are several different and more virulent strains of the pathogen, the

repeated use of resistant cultivars resulted in the selection of more virulent

strains and an effective breakdown in the level of cultivar resistance to the

disease. For this reason it is of great importance to monitor the incidence of

Verticillium wilt with repeated cultivation of a resistant cultivar.

Black root rot is caused by the soil borne fungus Thielaviopsis basicola, which

causes disease in over 137 species of plants (Honess at a1. , 1994). T basicola

survives for long periods in the soil as resistant resting spores. The wide host

range and resistant resting spores make T. basicola almost impossible to

eradicate from soil. Infection of cotton is favoured by soil temperatures below

20'C. Research in the USA has shown that severe disease symptoms result

when the population of the black root rot fungus reaches 100 spores per grain

of soil. Populations of 600 to 700 spores per grain of soil are commonly

observed in Australian cotton fields.

Black root rot contributes to seedling loss caused by the seedling disease

complex. Stand losses of 30% or more have been recorded. Seedlings affected

by black root rot are stunted and slow growing and crop maturity is delayed. In

California black root rot was regarded as a minor disease 30 years ago but is

now considered to be more serious than Verticillium wilt (Note: the defoliating

strains of Verticillium in the USA are more pathogenic than the strains currently

in Australia). Yield reductions of 25 to 509", were attributed to black root rot in

California (Garber at a1. , 1985; Hake at a1. , I 985) but the potential for yield loss

in Australia had not been quantified.

Black root rot was first observed in Australia in 1989. Since then its severity and

distribution increased annually. At the commencement of this project, black root

rot occurred throughout the Macquarie valley, the Namoi valley and the Darling

Downs, and was common in the Macintyre and Gwydir valleys. In some fields

100% of plants were affected. Anecdotal evidence suggested that black root rot

may increase the severity of Fusarium wilt (J. Kochman, Pers. Coinm. ).

Permanent bed systems may have increased the severity of black root rot by

increasing the population of the pathogen along the planting line.

An experiment was conducted at Narrabri Agricultural Research Station during the 1991-92 season to investigate the response of a range of currently available cotton varieties to irrigation and nitrogen treatments. This experiment, along with the date of planting experiments described by Tony Wells elsewhere in the conference proceedings, forms part of a long-term program to study the agronomic requirements of new cotton varieties. These experiments also provide data for development of crop simulation models including the Hydrologic program. This paper describes the yield and fibre quality results from the experiment and discusses the implications for inigation and fertiliser management of different varieties. Some recommendations also apply to dry land cotton production.

Due to the size and nature of the agricultural industry in Australia the adoption of subsurface trickle

irrigation (SDl) in this country has been limited due to bad experiences of early installations (Arithony,

1996). Underpinning these experiences was the failure of research at the time to fully identify and

communicate the potential benefits of the drip systems (Bristow et a1. , 2000). For these reasons it has taken

twenty years for SDlto re-establish itself as a viable irrigation alternative in the Australian cotton industry.

The large body of research from Israel and the USA has indicated that substantial increase in yield and water

use efficiency can be achieved through the installation on SDl for a number of crops (Camp at a1. , 2000). in

Australia some of these promised benefits have not materialised because surface irrigators here have been

described as the among the most efficient water users in the world (Arithony, 1996) and poor SDl

performance has been attributed to suboptimal management based on observed cotton water deficit stress

(HuIme and O'Brien, 2000).

The use and management of SDl on Vertosols in Australia is poorly understood and many comparative

studies have been treated with scepticism, (HuIme and O'Brien, 2000). Only two water balance studies have

been conducted on the system. A study on lighter soils in the Emerald Irrigation Area, (M. MCCosker, pers.

comm. ) demonstrated an increase in cotton yield and a doubling in WUE with SDl when compared with

flood irrigation. On a Vertosol, total water used was 20-30% less with SDl, however water and nitrate fluxes

(deep drainage), were significantly greater than under flood irrigation (Ian Gordon, pers. comm. ).

Research by the cotton industry funded program "Minimising Pesticides in the Riverine environment"(1993-

1996) found unacceptable levels of sediment and chemical pollutants in surface runoff water from furrow

irrigated cotton. Carroll et al. (1988) identified up to 80% of erosion was associated with rainstorm events,

particularly soon after flood irrigation, and pesticides and nutrients are transported with the runoff and

eroded sediment.