The Cotton Australia Grower RD&E Advisory Panels function in providing practical advice on research, development and extension (RD&E) needs and priorities within the industry. This advice forms important guidance to CRDC for strategic R&D planning, annual operation planning, development of Expressions of Interest and resultant CRDC decisions as to project investments.

Cotton Australia facilitates 4 advisory panels that are aligned with the CRDC strategic plan priorities. The panels consist of up to 40 grower, consultant or ginning Member Representatives from every cotton growing region in Australia.

The Transgenic and Insect Management Strategies Committee (TIMS) functions as a cotton industry stewardship group, with broad representation from growers, research organisations, crop consultants and members of the pulse and grains industries. The agricultural chemical, biotechnology and seed companies that provide crop protection tools to Australian cotton growers approach the TIMS committee for advice on issues associated with developing or amending resistance management plans for new or existing technologies. Cotton Australia is represented by 6 grower representatives, the TIMS Committee Chair, the Chairs of the three technical panels and the Executive Officer.

The Cotton Industry Biosecurity Group (IBG) serves to ensure that the cotton industry’s responsibilities under the Emergency Plant Pest Response Deed (EPPRD) are met. It is anticipated that the IBG will constitute 1 staff and up to 3 grower representatives of Cotton Australia as well as representatives from CRDC, Crop Consultants Australia, CSIRO, NSW DPI, QDAF and Plant Health Australia.

The incorporation of crop residues post-harvest can provide an important source of nitrogen (N) for the subsequent crop but can simultaneously lead to elevated nitrous oxide (N2O) emissions. The magnitude of N supply and corresponding N2O emissions strongly depends on the quality of the added crop residues, and soil and climatic conditions. However, little data is available for subtropical cotton systems. The primary aims of this study were to (i) quantify carbon dioxide (CO2) and N2O emissions, and corresponding emission factors (EFs) following cotton residue incorporation, and (ii) determine the contribution cotton residues have to soil N content for the subsequent crop. Using a semi-automated sampling system, CO2 and N2O emissions were monitored during a cotton fallow period following cotton residue incorporation under varying rainfall conditions compared to residue removal. The high C/N of the incorporated residues, low temperatures and the limited C substrate resulted in low N2O emissions. EFs were found to be 0.016 and 0.064% for average and high rainfall conditions, respectively which is significantly lower than the IPCC EF of 1%. The majority of decomposed residues were recovered in the soil of up to 68% with the remaining undecomposed and a very minimal amount was lost. There was a net mineralisation or loss/immobilisation observed across sites indicating soil conditions and management practices significantly influence N dynamics. The study suggests that the current IPCC methodology should be re-evaluated and that EFs need to be lowered to reflect the low N2O emissions from high C/N cotton residue N inputs. It also shows that effect of crop residues on soil N dynamics needs to be considered in N fertiliser management strategies in order to maximize the benefits from crop residue incorporation.

"When schools, families & community groups work together to support learning, children tend to do better in school, stay in school longer & like school more" (Henderson & Mapp, 2002)

" The key to improving student achievement is not parental involvement in schooling but parental engagement in learning" (Harris & Goodall, 2007)

The annual educational excursion to discover the Australian cotton story was once again a huge success for the year 12 Students of Gunnedah High School and Calrossy high School, Tamworth.

A number of research trials have been planned for the 2016/17 season which require an effective and accurate measurement of yield soon after harvest. Over the past few seasons trial coordinators have either relied on hand picking sections of treatments to estimate yields (which is time consuming), or designed trials so six modules could be weighed out over the weighbridge at at the gin.

CSD have a bale weighing trailer which is available for a limited time after their trial work is complete, and the wet weather following the 2015/16 harvest made it challenging to gain access to the trailer for local trial work in a small window of opportunity. The CGA trailer will have the same specifications as the CSD weigh trailer.

With the growth of the cotton industry in the Southern Valleys and with consideration of the climatic differences from the northern cotton growing region to the south, there is a requirement and need for research to be carried out within the local area, so the bale weighing trailer will prove to be a convenient and accessible resource to accurately weigh cotton round modules from research trials.

This project enables effective and timely research results for the Southern NSW cotton community

each season. It will also encourage on farm trials with more rigour due to replication of treatments

and effective measurement.

The 14th Australian Cotton conference was held at the Gold Coast , August, 2009. The objective was to run a successful conference whereby program content was beneficial to cotton growers and industry stakeholders.

Fusarium wilt continues to be an important constraint to sustainable cotton production. This project had a number of objectives to obtain data to improve the management of this disease.

Even though it has been dry, diseased samples suspected of being Fusarium wilt were still sent to DPI&F for analysis. A total of 252 diseased specimens have been examined during the course of the project from Qld and NSW. Of these 49% were positive for Fov, and of the positive specimens, 121 belonged to VCG 01111, which was the original strain identified from the Darling Downs, and two belonged to VCG 01112. There were some new recordings of Fov however the rate of reporting of new cases of Fusarium wilt has declined. The slower rate of reporting in recent years may reflect a combination of farm hygiene measures, decreased cropping area due to drought, and increased use of less-susceptible varieties. A new strain of the pathogen was detected in 2005 from the Macintyre valley. Sampling from the same area has not yielded further isolates of this type, indicating that this new isolate, which probably arose from a spontaneous mutation, has not spread. A new VCG code will not be designated to this new strain until a larger number of representative isolates are identified. A reference collection of preserved strains of Fov is being maintained at DPI&F laboratories at Indooroopilly. A data base, which includes all records of isolations of Fov made at the Indooroopilly laboratories is continually updated and is searchable under several fields such as, cotton variety, state, district or year.

Many of the current strategies to manage the disease have been developed as a result of the project work carried out at Graham Clapham’s property ‘Cowan’. The ‘Cowan’ trial site is recognised by the cotton industry as a high disease incidence site, providing unbiased information on disease management practices. Some specific outcomes include: (i) the identification of germplasm, with improved resistance to Fov, has been used in breeding program to provide new varieties with better resistance to Fusarium wilt, (ii) monitoring the reaction of varieties to Fov and development of a comparative varietal reaction guide has provided an independent disease assessment guide for growers, and (iii) the identification of some agricultural practices, such as crop rotations and residue management that may reduce the incidence of disease. The management strategies that have been developed have not increased pesticide usage.

There was no evidence in this study that non-pathogenic isolates of Fusarium oxysporum cross-protect cotton against Fov. Many of the isolates collected from cotton fields were actually root pathogens, although they were not vascular pathogens. Some isolates however were beneficial in reducing the effect of Pythium spp. on cotton. Silicon amendments were identified that reduced disease severity under glasshouse conditions when applied to field soil, but were not effective under field conditions. Application of high phosphorus significantly increased disease severity in glasshouse trials and requires further investigation.

The results from this project have had an impact on grower’s returns, value of properties, rural businesses and communities that service the cotton industry as well as processors and exporters. These results have been vital to plant breeders to assist them in producing less susceptible varieties. The research results obtained during this project have been widely disseminated throughout the industry.

A grower’s perspective of the impact of the research on disease management epitomises the value of this research. “The results of this research have played a major part of the success in slowing the rapid spread of Fusarium wilt that happened in the late 1990’s. By using the information obtained from the rotation trials and varieties with higher F rank, fields which have been unable to produce cotton for many years because of high Fusarium levels have returned economic yields in the past two seasons. Whilst we have come some distance in understanding this disease it still has the potential to cause serious crop losses given the right environmental circumstances. Therefore it is important to continue to screen new varieties and explore cropping practices that will halt its spread and enable production of cotton on highly infected fields again”.

This project evaluated options for selective control of aphids, studied the field epidemiology of cotton bunchy top disease and determined the suitability of relay crops for aphid pest management. Key conclusions were;

1) Acetamiprid plus pulse provided good control of aphids but flared mites, presumably because it reduced beneficial numbers. This will also be a risk if this product or other neonicotinoids are used against mirids.

2) None of the ‘soft’ soap or oil options alone provides adequate control of heavy aphid populations. Canopy oil may be effective if applied to lower density aphid populations (e.g. less than 10-15 aphids per leaf) in a regular program.

3) The biopesticides evaluated are unlikely to provide the high level of control provided by acetamiprid plus pulse. However, efficacy should improve as more field adapted strains are selected. Used early, these products may be effective at preventing aphid populations from increasing without flaring mites and with reduced resistance risk.

4) CBT appears to be relatively common in aphid populations. CBT affected plants were often observed in the centre of aphid hotspots – often only one or two infected plants are found. In 2005-06 we found CBT affected plants in aphid hotspots in 6 of 8 sites.

5) The latent period of CBT in cotton plants can be relatively short (about 10 days) but is likely to be influenced by aphid numbers (lower densities could have a longer latent period). This is complex and needs further experimentation to sort out.

6) Yellow dwarf forms of cotton aphid transmit CBT poorly compared to ‘normal’ sized aphids.

7) The rate of spread of aphid populations while they are in the apterous form (non-winged) is relatively modest e.g. it took about 40-50 days to travel 8m, both across and along rows. Once populations reach densities that produce alates (winged forms) the spread of aphids could be much faster.

8) Spread of CBT was much faster and higher when the infestations in the field were initiated with a CBT affected plant carrying a high aphid population, compared with those initiated by infesting a field plant with CBT infected aphids. This is likely due to movement of CBT infected aphids off the CBT affected plant compared with movement of clean aphids off the aphid infested plant due to the latent period.

9) In terms of risk of CBT outbreaks – generally low densities of aphids colonising plants means transmission efficiency is low and the latent period likely to be longer, which may severely limit the level of infection in field. Exceptions would be in years were season conditions generated high numbers of aphids and of alternative hosts with CBT – which could then colonise cotton crops at higher densities or situations where stubb cotton was abundant in a field and acted as a source of CBT carrying aphids.

10) The effect of CBT on yield is greater the earlier that plants are infected.

11) Lucerne and sorghum are good relay crops for aphid management as they host aphids that don not attack cotton on which beneficials and parasites could build up and move into cotton.

These outcomes significantly advance our understanding of aphid and CBT epidemiology and will be valuable to industry in developing management strategies.

Regular disease surveys have highlighted the changing status of cotton diseases over time and

provided valuable insights into the factors affecting their distribution and severity.

• The disease surveys provided overwhelming evidence that seedling mortality is not related to the

incidence or severity of black root rot but increases with increasing latitude

• The observed incidence of black root rot has decreased in the past three seasons, most likely as a result

of climatic conditions and drought-enforced fallows but has increased rapidly in the Lachlan and

Murrumbidgee Valleys.

• The rate of reporting of new cases of Fusarium wilt, now totalling 81 farms in NSW, has declined in

recent years, potentially due to farm hygiene, greater deployment of less-susceptible varieties and drier

conditions in spring.

• Fusarium wilt has been observed on 41% of the set of farms surveyed annually in NSW and is

spreading at a steady rate of increase among those farms

• The incidence of Verticillium wilt decreased recently in the Namoi Valley, probably due to greater use

of resistant varieties, although the disease is still observed in 45 to 60 % of fields surveyed annually

across NSW

• An apparent decline in boll rots over recent years probably reflects both the drought and the expansion

of the surveys into southern NSW, where summer rainfall is low.

Experiments were conducted to develop and/or evaluate control strategies for control of

seedling disease, black root rot and Fusarium wilt:

• High seed vigour index, while decreasing seedling mortality, was not related to seedling growth;

seedling mortality was not related to seed mass

• The fungicide DynastyTM consistently performed as well as, and sometimes better than, the standard

fungicides

• Seed treatment with fertilisers and other non-fungicidal products, were not effective in controlling

seedling disease, nor was Bion® in most cases except in crops with Fusarium wilt, suggesting that

Bion® may activate resistance against F. oxysporum f.sp. vasinfectum as a seedling pathogen.

• Seed treatment with Bion® activated resistance against Fusarium wilt and black root rot of cotton,

although its efficacy was variable

• In-furrow application of the fungicide azoxystrobin was very effective in controlling seedling disease in

some seasons at some locations.

• Delayed sowing decreased the period of exposure of cotton to conditions that favour black root rot and

seedling disease, even when cool and wet conditions coincided with the late sowing.

• Pre-plant and at-planting herbicides had no effect on the severity of black root rot or growth of seedling

cotton

• In comparison to continuous cotton, nine years of bare fallow did not eliminate arbuscular mycorrhizal

fungi (AMF) in the soil, although re-colonisation by AMF probably occurred, as the black root rot

pathogen, T. basicola, also colonised the fallowed plots in the absence of plant hosts.

• During bare fallows of up to four years at Bourke, AMF survived in sufficient numbers for normal

development of mycorrhizas in cotton

• AMF were not affected by transgenic cotton varieties

• Seed treatment with a plant flavonoid reputed to increase mycorrhizal development in the field was

phytotoxic at the recommended rate and no conclusion about mycorrhizal effects could be drawn.

• Evaluation of a commercial inoculum, putatively containing mycorrhizal fungi, showed that no

mycorrhizal fungi were present in the product.

Results of these experiments and observational studies have been incorporated in strategies

for integrated disease management and disseminated to the cotton industry by way of

publications, media releases, field days and meetings with growers and consultants.

Fusarium wilt of cotton is caused by the soil-borne fungus Fusarium oxysporum f. sp. vasinfectum (Fov). In Australia, 2 Fov strains are currently responsible for the disease, each belonging to a distinct vegetative compatibility group (VCG). Previous work showed that the 2 Australian Fov strains are genetically related to lineage A of native Fusarium oxysporum, suggesting their local origins.

This project aims to: 1) assess the risk of novel Fov pathotypes emerging from local Fusarium oxysporum population in cotton fields; 2) investigate the evolutionary potential for weakly pathogenic lineage A isolates of native Fusarium oxysporum to become more virulent; and 3) determine the competitive ability of different strains or genotypes of Fov.

Our work showed that Fusarium oxysporum present in the soil of cotton fields consists of 3 major lineages, A, B, and E. The presence of lineage A highlights the likelihood that new strains of Fov may emerge in the future. In addition, the difference in lineage composition between uncultivated soils and cotton fields is noticed, with the dominant form of Fusarium. oxysporum being lineage E in cotton fields but lineage B in uncultivated soils. The evolution of virulence in Fov was studied by carrying out the inoculation – re-isolation – re-inoculation infection cycles successively on a susceptible cotton cultivar. A mildly pathogenic isolate of lineage A became more virulent, causing more severe disease symptoms after 10 infection cycles, and importantly, correlated genetic changes were detected in its offspring isolates. This suggests that weakly pathogenic Fusarium oxysporum isolates of lineage A can become virulent Fov and continuous exposure to susceptible host plants plays an important role in this process.

Based on 350 isolates collected from 6 cotton growing regions in 2002 and 2004, 28 genotypes of Fov were identified, with 21 in VCG 11 and 7 in VCG 12. VCG 11 can be further divided into 2 subgroups and subgroup I-B may represent a new strain of Fov as all members of this subgroup are incompatible with either known Australian VCG. The occurrence of new Fov strains in cotton fields was also detected in other regions like Mungindi. VCG 11 is wides-spread, while VCG 12 is restricted to the Boggabilla area. No genetic structure was found among Fov populations at broad geographic scales, but interestingly some structure was found in the Boggabilla area, with the population in two fields being different from the others. In addition, variation in virulence was observed among different genotypes of Fov.

Field surveys showed that Fov populations may change over time because in one Boggabilla field the dominant Fov genotype was 11-A in 2002 but 11-B in 2004 and, furthermore, genotype 11-A was undetectable in 2006. This change is probably driven by the increasing level of resistance in newly released cotton cultivars planted in the field as our glasshouse trials showed that genotype 11-B is more aggressive than genotype 11-A on the tolerant cultivar, suggesting competitions between strains or genotypes of Fov.

Fusarium oxysporum occurs at comparable levels in the soil of cotton fields (Fov infested or free) in the Darling Downs, Boggabilla, and Moree, however, a clear declining tendency was observed in the frequency of Fov in Fusarium. oxysporum population from the Darling Downs soil to Moree soil. Future studies will focus on soil impacts on Fov since, as a soil-borne fungus, both aggressiveness and saprophytic ability are inevitably influenced by soil biotic and abiotic factors. Insights into how life history traits of Fov and soil factors interact to determine selection for virulence and persistence of the pathogen would aid developing effective disease management strategies.

This project has advanced the use of soil and tissue testing such that growers and advisors are now better able to optimise fertiliser use and have greater confidence in their management practices to provide sound nutrition for cotton crops. Adhering to these best management practices will improve the use-efficiency of fertilisers and reduce the potential for damage to the environment. The large quantities of macro-nutrients removed in seed cotton should be replaced to avoid depleting soil fertility.

Legume cropping can dramatically reduce the requirement for N fertilisers and substantially enhance soil quality. Legumes afford improved soil microbial biomass and reduced soil strength which enables better root growth and facilitates cultivation and tillage. Also, crops are better nourished due to improved availability of nutrients. Economic analyses have demonstrated higher gross margins from legume-based systems due to elevated cotton yields and the reduced requirement for N fertiliser.

By avoiding the overuse of N fertiliser, we can reduce greenhouse gas emissions via nitrous oxide. Further, atmospheric carbon dioxide can be sequestered and soil organic matter increased where tillage is minimised and permanent bed systems installed. Greater research effort is now being placed on the efficiency of N fertiliser use, and the regional extension officers are assisting this. This research offers the industry an opportunity to reduce N fertiliser use and greenhouse gas emissions, without reducing yield.

The results of this research are being extended to the cotton industry but have not been widely adopted by the industry. Further extension activity is planned and training for the extension team and industry on cotton nutrition and soil health issues.