Final Report for Cotton Catchment Communities Project 1.02.06 Honours Thesis A Method For The Simple And Rapid Determination Of Deep Drainage And Its Requirement

The Australian cotton industry depends heavily on genetically engineered Bt cotton (currently in the form of Bollgard II®) which provides resistance to the key pests of cotton, larvae of the moths Helicoverpa armigera and H. punctigera. Bt cotton has enabled substantial reductions in the use of insecticides, provided greater flexibility on cotton farming systems, and made the crop easier to grow. However, as with most pest management tactics, there is potential for the pests to develop resistance, and to counter this the Australian cotton industry has developed comprehensive Resistance Management Plans (RMPs), observance of which is mandatory for growers of Bt cotton. A traditional component of RMPs, dating from resistance management of conventional insecticides, is pupae busting, or cultivation of the soil to destroy overwintering (and potentially resistant) pupae. However, pupae busting incurs financial, agronomic and environmental costs. It restricts the implementation of minimum tillage techniques which can help prevent erosion, conserve soil moisture and enhance soil carbon. Moreover, we have demonstrated through modelling studies in this project that in modern Bt cotton systems, with high fruit retention and early maturation, many potentially resistant insects are emerging before overwintering diapause is initiated, and are thus not vulnerable to pupae busting. There is a need to develop tactics for RMPs that can fill this gap.One potential tactic is to target moths instead of pupae, using the attract-and-kill technology Magnet® which was developed by the researchers in this project during early work in successive Cotton CRCs. Magnet® consists of a mixture of plant volatile compounds which, when combined with small quantities of insecticide, can attract and kill adult Helicoverpa spp. moths. It has impacts beyond the area in which it is applied, but with careful placement it might be able to kill proportionately more potentially resistant moths from cotton than susceptible moths from refuge crops and other sources, thereby enhancing the genetic dilution effect provided by refuge crops which are another component of RMPs. A farm scale trial conducted during this project indicated the feasibility of this approach, and helped develop techniques to be used in a larger, area-wide trial of the approach to be conducted over the next three years. If successful, this trial could lead to the development of more robust RMPs, and the reduction of elimination of the requirement for pupae busting.

The Australian Cotton Comparative Analysis provides the industry benchmark for the economics of cotton growing in Australia. The report focuses on the economics of the 2015 crop from growers across the different cotton-growing valleys. It also presents trends that have been measured against more than ten years of data. The Cotton Comparative Analysis is a joint initiative of CRDC and Boyce Chartered Accountants.

Enhancing the Efficiency of Bt Refuge Crops within a Changing Cotton Environment

The spring edition of CRDC's magazine, Spotlight, takes an indepth look at crop nutrition and disease in preparation for the 2019-20 cotton season. In it, we investigate the results from the More Profit from Nitrogen project, led by CRDC under the Department of Agriculture’s Rural R&D for Profit program, which has provided growers with a greater understanding of how to reduce inputs and increase efficacy. We also look at verticillium wilt and the projects CRDC is investing in to better understand the pathogen, how to predict inoculum levels in the soil and how to manage it - and recognise Dr Linda Smith, the well-deserved recipient of the 2019 CSD Researcher of the Year, for the significant body of work she has undertaken in this area.

In this edition, we also feature several key events focused on innovation and technology, including evokeAG and the Australian Agriculture Immersive Technology Conference where the future of ag was on show. We also welcome new partnerships to take agtech to the field, with the commercialisation of canopy temperature sensors, in which CRDC has been a long-term investor.

As growers try to preserve soil moisture, and many fields sitting fallow, attention also turns to weed control and management of herbicide resistance. The Crop Consultants Australia have some sage advice for us all in their regular column, which is fully backed by our research and industry initiatives to bring this issue to the fore. CRDC has invested heavily in resistance research and we will continue to report on these results as they come to hand. In this issue we feature windmill grass and the evolution of resistance, which will lead us to better management through understanding.

Abstract of Weed resistance risk management in glyphosate resistant cotton final report

Early season thrips present a challenge to pest management decision makers. While nymphs and adults cause early season damage to terminals, leaves, buds and stems, they

are beneficial as a key predator of spider-mite eggs, especially later in the season and have

proven to delay the development of mite outbreaks in cotton.

The growth of grain legumes into Australian farming systems has been increasing in the 1980’s. Part of their value in crop rotations is their ability to fix atmospheric nitrogen in symbiosis with Rhizobium. This may decrease the need for nitrogen fertilizer for crop following the legume crop. This is because some of the fixed nitrogen may be left in the legume crop residue after grain harvest and thus become available to the following crop. Subsequently legumes have a reputation of maintaining or increasing soil nitrogen status.

Many management practices of the farmer will influence the amount of nitrogen fixed by the grain legume crop and thus the amount left for the following crop. Practices like ground preparation, inoculation, fertiliser usage, irrigation and crop residue management all affect the amount of nitrogen fixed and left by the legume crop. The following review covers these and other management practices. As well, certain biological aspects of nitrogen fixation are discussed giving background to the effects of management practices

Project to assess the role of wet season cover crops and minimum tillage systems in facilitating early sowing of cotton in the Ord River Irrigation Area.LR 1.1

A survey form asking the cost of weed control, the major weed problems and the herbicides used was sent to fifty two cotton growers from the seven major cotton areas of New South Wales. On average, weed control costs the cotton grower $187/ha annually. The major components of this cost are $761ha for herbicides in cotton and $671ha for hand chipping. The most important cotton weeds are noogoora burr, Bathurst burr, nutgrass, Chinese lantern and peach vine. Although these weeds are problems on a large proportion of the cotton growing area, repeated use of herbicides, cultivation and chipping are reducing their importance. However, nutgrass, which is a major weed problem on 15% of the cotton area, is escaping the weed management practices currently used and is rapidly spreading in many fields. Brown beetle grass is an important weed on irrigation channels and is not controlled by the registered herbicides. Trifluralin, diuron and fluometuron herbicides are used in cotton by over 60% of cotton growers. Glyphosate is used by 59% of growers in tallows before cotton, and atrazine, diuron alld glyphosate are used by over 60% of growers to control weeds on irrigation channels.