The aim of this project was to develop tool/s to inform grower decision making with regards to Verticillium wilt. Verticillium wilt is caused by the soil-borne fungal pathogen Vertillicum dahliae. Once introduced to a field, V. dahliae is considered impossible to eradicate. Failure to control the build up of disease inoculum can result in very large yield losses and fields becoming unsuitable for cotton production. Reports from growers estimate yield losses range from 10–62 per cent. As there are no control options for Verticillium, recommended best management is to rotate out of cotton to non-host crops until levels of V. dahliae. sufficiently reduce. Understanding the risk of verticillium disease prior to planting would mean growers could make informed decisions about whether it was safe to go back to cotton, potentially preventing significant yield losses.

Key outcomes:

- Diversity of V.dahliae virulence even within strains is quite high and some Australian isolates can cause more severe damage compared to international isolates.

- The development of a V. dahliae specific inoculum quantification assay was extremely challenging and semi-successful. The molecular soil assay can detect V. dahliae and the sensitivity of detection was 10-30 ppg in naturally infected soil. This is not sensitive enough when one propagule per gram of soil is enough to cause disease in more severe strains. A disease matrix was developed to industry that provides a guide to disease risk.

- A methodology was developed to determine the strain (VCG) of V.dahliae in soil using a combination of the dry plating soil assay and sequencing.

- A plant tissue molecular assay was developed that is faster than traditional isolating techniques and is capable of diagnosing V. dahliae and providing VCG in a higher proportion of infected plants. This molecular tool means industry has ability to quickly diagnose Verticillium down to VCG and growers and consultants can quickly determine which strain of V.dahliae they have, enabling Verticillium risk to be factored into decision to grow cotton.

The 2022-23 CRDC Researchers' Handbook is a key resource for all researchers working with, or interested in applying for funding from, CRDC.

Updated annually, the Handbook outlines the key information researchers need to know, including key dates, the application process, funding and stipends available, the payment, evaluation and reporting processes and the CRDC’s intellectual property policy. These, and other critical details needed by researchers - like CRDC's new grant management system, Fluxx - are provided in the Handbook.

This document provides a brief outline of the projects CRDC has invested in for 2022-23 (current as of May 2022).

The autumn 2022 edition of CRDC's magazine, Spotlight, continues the focus on sustainability and environmental responsibility.

Recent events in the carbon trading market have growers contemplating their carbon status and what they should potentially do with any credits. In this edition, we bring you the key things to consider before embarking on soil carbon farming.

In addition, to help growers continue to improve their carbon footprint, we’ve included salient research from leading scientists on how and why nitrogen fertiliser must be better managed for the industry to meet its commitments to sustainability. Not only has trial work been undertaken to ascertain exactly the N requirements of cotton crops, and how and when they use it, but economic analyses of current versus best practice paints a clear picture: we have all the knowledge – we now need action.

OBJECTIVES OF VISIT: * To attend the 1992 Beltwide Cotton Production Research Conferences organised by the National Cotton Council o. America which included the 52nd Cotton Disease Council. To review the latest developments in the biocontrol o seedling diseases and verticillium wilt of cotton with colleagues at the USDA 'Biocontrol of Plant Diseases laboratory at Beltsville

The main aim of this trip was to accept an invitation from the British Society of Chemical Industry to deliver a paper at their 'Resistance 91' international symposium. While in Europe, the opportunity was taken to review the latest developments in the agrochemical industry1s R & D programmes. including both biological and conventional chemistry innovations. More detailed notes are given in an Appendix.

Aposter was displayed by Ms Greenhalgh titled' Diagnosis of Soil structural Conditions', co-authored by David MCKenzie and Donald MacLeod. It was the only display or presentation that dealt with the practical assessment of soil structure in the field. This poster was highly commended for its content and presentation. It was ranked one of the top 4 posters out of 160 posters by the judging panel