This report presents and summarizes the outcomes of five years of research into enhancing integrated pest management (IPM) in cotton production systems. Multi-year field and laboratory experiments aimed to answer pest management related questions developed with industry input and relevant across the different cotton growing regions. Analysis and synthesis of experiments have shown a number of important outcomes:

1. We have further unravelled the myriad factors influencing the effect of insect honeydew on fibre quality and factors that contribute to its reduction in the field. The presence of insect honeydew in cotton is complex and problematic since the remedial rainfall that reduces stickiness in cotton, has the potential, under some circumnstances, to increase the risk of sooty mould development, another factor that diminishes cotton quality and can lead to penalties.
2. The host range of SLW was further confirmed and key hosts identified which is critical when considering management strategies to reduce overwinter survival and predict risks from outbreaks.
3. Studies on the retention of SLW DNA in the gut of key predators wers completed and will be used to identify the most significant predators.
4. Several new weed hosts of this disease were confirmed, potentially improving prediction of seasons with higher risks from CBT.
5. Seed treatments such as Cruiser would not be effective in preventing transmission of CBT but Cruiser Extreme could reduce the infection rate by 50%. Application of folair sprays against aphids just after aphids entered the crop, or 24 hours after they entered the crop would not be effective at preventing initial transmission but may retard secondary transmission..
6. We found in the central and southern cotton areas, the currently employed SLW sampling methodology inadequately predicts populations, potentially reducing the timeframe for optimal management decisions. The groundwork for development of new strategies was completed and will be developed in a subsequent project.
7. The IPM fit of new insecticides was assessed and a number of new IPM compatible insecticides have been added to Table 3: “Impact of insecticides and miticides on predators, parasitoids and bees in cotton” in the Cotton Pest Management Guide.
8. Fipronil and clothianidin were compared as management options for Green vegetable bug (GVB) and mirids. Both compounds were effective against target pests and improved yeild, but both also had negative impact on some predators (including Coccinellids) and one had high potential to flare mites. The complexity of these experiments highlighted the challenges involved in pest management decisions.
9. Thrips control with alternative seed treatment options to neonicotinoids was poor, indicating that these biologicals could not replace currently used chemicals. In new cooler regions thrips larvae were controlled by neonicotinoid seed treatments but benefits to yield did not occur probably due to low thrips abundance.
10. Assessing the relationship between boll age and susceptibility to GVB damage. GVB nymphs and adults inflicted most damage on five day old cotton bolls which usually aborted within days of being damaged, while older bolls continued to develop but exhibited staining and tightlocking.
11. Evaluating various insecticides used to manage SLW to understand their different modes of action We were unable to assess the effects of SLW insecticides as low whitefly numbers precluded conclusions resulting from a single application of whitefly insecticides, though our efforts will be continued in the future.
12. Providing expert advice to consultants and growers throughout the season and rapid responses to critical pest problems Expert advice was provided to growers and consultants throughout the year via phonecalls, e-mails and personal interactions. Support was given particularly in 2016/17, a high pest year that threw up many questions about occasional pests and their management.
13. Investigating the simulated effects of early and late flower damage by thrips and mirids on yield and maturity With respect to simulated thrips damage, the removal of one weeks’ worth of flowers at peak flower or cut-out was generally not severe enough to cause yield loss. More extreme, early season flower removal that simulated mirid damage had variable results on yield and maturity depending on the severity of the treatment and the regional climatic conditions, with higher risk of yield loss in southern areas. These experiments will be repeated across regions for verification.

The outcomes of this project have added to the current understanding of cotton pests, their assessment and impact on plants as well as their management and control options. They have also contributed to the better understanding of plant responses to pests which may potentially change management practices of some pests. Further, they have highlighted the interactions between plants, insects and other organisms, and the climatic factors that affect these interactions. What has become clear through the regional experiments is, that insect management decisions in the different cotton growing areas are governed by season length, and that the wrong decision in a short season area can have great consequences with respect to yield loss. These outcomes reinforce the importance of IPM in the cotton system and, once published and extended to the industry, will guide growers and consultants to make more informed decisions and perhaps influence the degree to which some pests are managed and tolerated.