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.

Within the national framework for biosecurity, all commonwealth and state governments and plant industries who are signatories to the Emergency Plant Pest Response Deed (EPPRD) formally commit to preparations that include; surveillance for key biosecurity risks, a chain of command for reporting suspected incursions, decision making processes for responding to confirmed incursions and industry recovery from confirmed incursions.

Cotton Australia is the cotton industry member of Plant Health Australia Ltd. and signatory to the Emergency Plant Pest Response Deed. The EPPRD specifically requires signatories to undertake information and awareness of EPPRD requirements with their members to demonstrate response preparedness. This can be reported in the signatory annual Biosecurity Statement (Schedule 15).

During the 2008-13 CRDC Strategic Plan, CRDC worked with industry and state governments to implement routine surveillance for exotic diseases and commence the development of contingency planning for specific, high risk exotic incursions for industry to implement if the situations eventuate. State governments have instigated 'biosecurity training' for their research staff to increase researcher awareness of processes for reporting and responding to suspected and confirmed incursions.

The industry needed to do the same, creating a network of human capacity at the grass roots of the industry - growers and their RDOs, consultants and Cotton Australia Regional Managers - that are aware of the role they may play in an incursion event. The thinking and decisions taken in the early stages of an incursion may be critical in determining the feasibility of an eradication response.

This project undertook to raise grower and consultant awareness and knowledge of the processes that will occur in the event that a cotton biosecurity incursion is confirmed.

In the majority of cases, growers do not have a problem with excessive vegetative growth in their cotton crops. It is more likely that a field is not growing to potential. Factors which have a big bearing on early season vegetative growth include:Soil structure/texture. Temperature. Irrigation management. Nutrition management.

Nitrogen management has to be good for best yields, but factors such as soil condition, irrigation and pest management may have greater effects on cotton yield than N rate. We have had much improved cotton yields in the past few years. We believe that is due more to improved utilization of N by plants than to increased application of N. In other words, improved soil management, irrigation scheduling and pest management have allowed the cotton plants to use N more efficiently. One point of importance is that high yields deplete the soil of nutrients rapidly. For example, there is the equivalent of 11 kg N in each bale, so 10 bales/ha will remove 110 kg N/ha from a field each year. The practice of burning stubble will also encourage loss of nutrients.

Cotton production has grown to become one of Australia’s most important agricultural

industries, with several regional economies supported by its development. Growing

cotton is an intensive land use, requiring cultivation of the soil, inputs in the form of

fertiliser and pesticides, and a reliable supply of water. Cotton is a significant user of

arable land and irrigation water in several catchments in New South Wales and

Queensland. In recent times, the industry has been proactive in developing production

systems that are both profitable and sustainable. For example, it has developed systems

of integrated pest management with reduced use of pesticides for dryland and irrigated

production, as well as improving water use efficiency for irrigated cotton systems.

This guide is a resource for improving riparian land management on cotton farms.

Riparian land is important because it is economically and environmentally productive.

Intensive agricultural production systems like cotton growing can affect waterways,

downstream water users, neighbours and communities. Careful management of

riparian land on cotton farms can help minimise these effects, and result in

environmental and aesthetic benefits for cotton growers and their families.

Riparian land is any land which adjoins, directly

influences, or is influenced by, a body of water.

This guide provides information on how best to manage riparian land. Different

management options are provided, with the science underpinning these options

described so that on-farm decisions can be made based on the best available information.

It is intended that the guide be used to complement existing information on sustainable

cotton production, as well as to assist the development of other products and materials.

For example, material in the guide could be used by the cotton industry, government

agencies and other groups to develop:

■ projects and activities to restore and improve riparian land;

■ best management practices, codes or plans;

■ workshops to increase awareness and skills;

■ fact sheets on specific issues of riparian management; and

■ presentations to landcare, farming and community groups.

Provided that the original source of the material is acknowledged, reproduction of parts

of the guide in other products is encouraged.

The guide has been developed by the Cotton Research & Development Corporation,

Australian Cotton Cooperative Research Centre, Land & Water Australia, the New South

Wales Department of Sustainable Natural Resources and the Queensland Department

of Natural Resources and Mines. It is recognised that today’s best practice may not be

tomorrow’s. As such, it is expected that this guide will be reviewed and further improved

from time to time, based on grower experience and new scientific knowledge.

In order to determine where soil and water salinisation may arise, information which is

related to each biophysical or causal factor (i.e. agronomy, geology, etc.) needs to be

mapped. For example, geological and hydrological components can be represented,

respectively, by estimates of salt storage and deep drainage across a given irrigated area.

When these independent causal factors are stored in Geographic Information Systems (GIS), the interaction between factors can be related to where salinisation occurs, and therefore determine if and where these conditions may be met elsewhere. This is essentially the basis of Salinity Hazard mapping, where a Salinity Hazard is defined as the extent to which natural

physical characteristics, excluding land cover, predispose a landscape to salinisation.

However, consistent and repeatable methods of generating biophysical or causal factors is time consuming and expensive. This often makes extrapolation and comparison from area to area difficult. The underlying aim of this project is to use similar methods to generate independent maps of these causal factors, store the information in GIS format and generate Salinity Hazard maps at the district level.