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A thirty year study of the ecology of 'Helicoverpa' spp. in inland Australia (see abstract for the presentation by Peter Gregg) has provided a comprehensive picture of short and long term changes in host plant abundance in different inland habitats (floodplains, grasslands, acacia shrublands, chenopod shrublands, sandy deserts and stony downs). The presence or absence of known host plants for Helicoverpa spp. was recorded at over 3,300 randomly selected sites in inland Australia. The Millenium Drought in 2001-2009 which severely affected southeast Australia(Van Dijk et al. 2013, Water Resour. Res.,49, 1040-1057) significantly affected host plant abundance in the acacia shrublands and to a lesser extent in the grasslands.

Site-specific measurements of the apparent electrical conductivity (ECa) of soil using the EM38 were correlated with near-simultaneous neutron probe readings over periods of moisture extraction by an irrigated cotton crop. Thirty sites were monitored from three ECa zones within a 96-ha field of grey Vertosol soil 30 km west of Moree, New South Wales, Australia. This study differs from previous approaches by reporting the effect on ECa of a wetting front (irrigation) reaching a single ECa measurement point in a field and by using polyethylene neutron probe access tubes so that the EM38 could be operated directly over the same site measured by a neutron probe. We report strong correlations (r = 0.94) between neutron probe counts (CRR) averaged to a depth of 40 or 60 cm and ECa from an EM38 held in the vertical mode 20 cm above the soil surface. All combinations of EM sensor height (0-1.2 m) to neutron probe measurement depth (0.2-1.4 m) returned correlations >0.85. The relationship between CCR and ECa was linear for the purposes of estimating water content over a range of background ECa levels. More critical modelling suggested a slight curve (logarithmic model) fitted best. The range of surface-surveyed ECa from the start of irrigation (refill point) to fully irrigated (full point) was ~27mSm⁻¹ for this Vertosol, where surface ECa readings typically ranged from 50 to 200mSm⁻¹. We suggest that the calibration of ECa to CRR might be effected by a two-point measurement of the soil, namely at both upper (field capacity) and lower (wilting point) ECa values, and a site-specific calibration template generated by extending these point measures to whole-field surveys.

Many Australian cotton farmers are interested in using organic waste products such as composted cotton gin trash as soil amendments because of perceived benefits to soil health and the environment. However, detailed information on the relative benefits and costs involved is not readily available to cotton growers who farm on clayey Vertisols. The objective of this study was to quantify soil changes in a farmer-established trial to evaluate the potential benefits of applying composted cotton gin trash and/or lime to a Vertisol. Selected soil properties were measured in an experiment located on a commercial cotton farm near Goondiwindi in southern Queensland, Australia. Cotton gin trash compost improved potassium availability and soil microbial biomass in soil, whereas lime improved only the latter.

Magnet® is an attract-and-kill formulation based on plant volatiles which is currently undergoing product evaluation trials on about 20,000 ha of cotton, and smaller areas of other crops, in Australia. It is based on a blend of five plant volatiles, previously shown in olfactometer studies to be attractive to both sexes of 'Helicoverpa armigera' and 'Helicoverpa punctigera'. These noctuid moths are key pests of cotton, and also affect many other crops, in Australia. This presentation will discuss the area-wide effects of treating individual fields, or contiguous areas of cotton, with Magnet® containing small quantities of the insecticides methomyl and thiodicarb. Methods used to estimate the numbers of moths killed, and simple models to predict the impacts on oviposition, will be described. 'Helicoverpa' spp. moths are extensively mobile within and between fields, and treated areas appear to act as population sinks, over distances of several km. Substantial reductions in oviposition can be obtained, not only in treated fields but in fields some distance away. Magnet® is applied to less than 2% of the area of treated fields, thus allowing beneficial predators and parasitoids to survive in the larger untreated area of the field. Attract-and-kill with formulations based on plant volatiles offers considerable promise as a component of area-wide integrated pest management for 'Helicoverpa' spp. Potential applications in resistance management for transgenic crops will also be discussed.

The Australian cotton industry follows resistance management plans (RMPs) to reduce the risk of developing Bt resistance in 'Helicoverpa' moths. We are investigating the potential of "moth busting" using a plant volatile-based moth attractant (Magnet®) for attract-and-kill, targeting potentially resistant moths emerging in late season cotton. Following a pilot trial in the 2011/12 season, we conducted our first large-scale field trials in the 2012/13 season in the Upper Namoi region to determine, whether, on an area-wide basis, appropriately timed and placed applications of attract-and-kill can reduce the numbers of potentially resistant 'Helicoverpa' moths emerging and surviving in Bt cotton in late summer/early autumn. The field trials involved treating about 1500 ha of transgenic (Bt) cotton in each of two locations. Each location had replicated fields of treated and untreated cotton, and fields of pigeon peas (required as refuge crops in RMPs) as well as other 'Helicoverpa' host crops. Light trap and pheromone trap data demonstrated that catches of 'Helicoverpa' moths in cotton were suppressed during and soon after Magnet® applications, and that there appeared to be no impact of the treatments on moth populations in the refuges. The host origins of moths killed by the attract-and-kill formulation are being determined by stable carbon isotope and lipid analysis, and will be compared with those of the general moth population obtained from light and pheromone traps. Bt resistance levels are being monitored and will be compared between treated and untreated regions within the study area, and with other cotton growing regions.

The Australian Heliothis complex consists of five described species of which two, H. armigera (Hubner) and H. punctigera Wallengren, are serious agricultural pests. Both are highly polyphagous but only H. armigera attacks cereal crops, including maize. H. armigera has developed resistance to insecticides but H. punctigera has not. The two pest species are very similar but can be separated on morphological criteria in the adult, pupal and late larval stages. The eggs and small larvae are indistinguishable except through electrophoretic variation, being fixed or almost so for different alleles at seven loci. Differences in the ICD and PGD bands can be used to indicate when the potentially resistant species H. armigera is present. The genetic distance between H. armigera and H. punctigera is 0.34, lower than the comparable value for the two American pest species. The percentage of loci which are polymorphic and the average heterozygosity are also relatively low. Genetic distances between widely separated populations are less than 0.01 in both species, and the same rare alleles are present in most populations. These results can be explained by extensive migration. Both species are long distance migrants and can be found in areas remote from cultivated hosts. The rapid spread of resistance in H. armigera is probably due to migration.

Background & Aims: Previous studies revealed that cotton plants grown on soils with low available-P were accessing significant non-fertilizer P sources. This suggests that cotton can access stable-P pools from soil. This study examined cotton's ability to utilize sparingly soluble P sources in comparison with wheat and white lupin. Methods: Plants were grown for 45 days in a Vertosol supplied with AlPO4 and hydroxyapatite, and NH4-N or NO3-N. A ³²P dilution technique was used to determine the availability and plant uptake of P from these P sources. Results: Three species differed substantially in P acquisition from the P sources. When averaged over N sources, the proportion of P in shoots sourced from AlPO4 was 89%, 54% and 19% for wheat, cotton and white lupin, respectively. When supplied hydroxyapatite, white lupin sourced 75% from the added P, in contrast to 36% for wheat and 17% for cotton. NH4-N nutrition increased the availability of hydroxyapatite to all the species and AlPO4 to cotton and white lupin. Conclusion: Cotton is inefficient in utilizing sparingly soluble P while wheat is efficient in mobilising AlPO4 and white lupin is efficient in using hydroxyapatite. The superiority of wheat in AlPO4 utilization may be related with its high root length density.

Cotton production is an important rural industry in Australia. Disease pressure from emerging pathogens such as 'Thielaviopsis basicola' threatens to reduce production. Wide-spread application of Best Management Practices, a desire to have a reduced environmental impact and community demand for more sustainable produce means alternatives methods to treat disease are becoming more important. This study has investigated the use of three disease reduction strategies; soil bacteria, organic soil amendments and plant derived proteins to treat black root rot in Australian cotton.

The genus 'Lygus' does not occur in Australia. Its nearest analogue, in terms of biology, ecology and pest management, is the green mirid 'Creontiades dilutus' (Stål) (GM). Other papers dealing with the damage, economic thresholds, chemical control and pheromones of GM will be presented at this conference. The aim to this paper is to provide an overview of the biology, ecology and management of the species as background to these presentations. 'C. dilutus' is one of two significant Australian pest species in the genus 'Creontiades Distant', the other being the brown mirid, 'C. pacificus' (Stål).

Black root rot is a soil-borne fungal disease affecting cotton seedlings upon germination. Disease symptoms include stunted or slow growth early in the season compared to surrounding healthy plants. Diseased plants show blackening of the root and reduced number of lateral roots. The blackening is due to both necrosis (rotting) of the external layer of the root tissue (cortex) and the build-up of the fungal pathogen dark spores (reproduction bodies containing melanin) on the root surface. Previous laboratory studies indicated that 'T. basicola' could complete its life cycle on cotton within 72 hour post-inoculation, when spores (thin-walled endoconidia and thick-walled chlamydospores) appeared on the surface of the inoculated roots. The fungus can infect the centre of the root, causing a "black heart". Figure 1 below illustrates the black root rot disease cycle and shows the morphology of the fungal spores. The fungal pathogen causing black roo rot, 'Thielaviopsis basicola', is found in almost every inspected cotton farm in Australia and, while it does not kill the plant, it causes substantial loss of yield and severe cases might open the root up for infection by Pythium or Rhizoctonia. It has been considered a significant threat to cotton and other crops in Australia, especially in cooler areas and seasons. The symptomatic stunting of seedlings stays with the plant through to maturity, causing up to 40% yield loss, depending on the season, environmental conditions and cotton growing practices. When assessing for black root rot one should note that plants that are badly affected early in the season may not continue to show symptoms later in the season as the dead cells of the root cortex may slough off when growth resumes in warmer weather. However, the spores released into the soil increase the soil reserves of the pathogen. In following seasons, one may no longer observe patches of stunted growth as the fungal spores may have spread and the entire field might be infected.

Black root rot is a seedling disease caused by the soil-borne fungal pathogen 'Thielaviopsis basicola', a species with a worldwide distribution. Diseased plants show blackening of the roots and a reduced number of lateral roots, stunted or slow growth, and delayed flowering or maturity. It was first detected in cotton in Australia in 1989, and by 2004, 'T. basicola' reached all cotton-growing regions in New South Wales and Queensland and the disease was declared as an Australian pandemic. This review covers aspects of the disease that have implications in black root rot spread, severity and management, including the biology and ecology of 'T. basicola', host range and specificity, chemical and biological control of 'T. basicola' in cotton cropping systems, and crop rotations and host resistance. This review is of special interest to Australian readers; however, the incorporation of ample information on the biology of the pathogen, its interactions with plants and it relation to disease management will benefit readers worldwide.

Accurate identification is important for the management of weed species for a range of different reasons including the selection of effective herbicides, implementing timely management before seed set and for the selection of appropriate biological control agents. Bladder ketmia ('Hibiscus trionum' L.) is extremely variable in Australia with at least three weedy forms occurring. This study assessed variation within and between these forms in a range of field and glasshouse studies. The field studies illustrated a number of differences between narrow and wide leaf forms of bladder ketmia, and determined that two phenotypes of the wide leaf form existed, one with a cream or yellow centred flower and the other with a red centred flower. Glasshouse studies were used to evaluate the biotypic differences between 29 populations of 'H. trionum' taxa collected broadly from within the northern grain zone (Emerald in central Queensland to Narromine in central New South Wales). There was significant variation between 'H. trionum' taxa in many of the 67 growth parameters measured. There was also significant variation in these parameters within different populations of the same taxon. These studies indicate two important areas for further investigation. Firstly, management recommendations, including the timing and choice of herbicides, need to be re-evaluated since important differences exist within this species. Secondly, a taxonomic review of taxa under the name 'H. trionum' is needed to determine if it comprises more than one species.

The project aims to provide improved understanding of the ecology of 'H. punctigera', especially immigration from non-cropping regions where there is no selection pressure from Bt cotton, notably inland Australia. Field surveys of inland regions during the winter breeding period will determine host plant responses to rainfall and abundance of 'Helicoverpa' larvae, and spring trapping studies and surveys in spring crops will estimate levels of migration. This project follows work in 2009 when we collaborated with Sharon Downes (CSIRO) to determine the extent of winter breeding of 'H. punctigera' in the floodplains of the Diamantina and Eyre Creek systems, and collect larvae for testing to determine whether Bt resistance was present in these populations. We have now conducted six field trips to far western Queensland, and established a network of pheromone traps serviced by local collaborators (notably schools) and permanent vegetation monitoring sites in a transect from Bourke to Birdsville and Bedourie.

The title of this article is deliberately provocative. Pupae busting has been an icon of resistance management for the cotton industry, since the first Insecticide Resistance Management Scheme (IRMS) for pyrethroid insecticides in 1984. Combined with windows for application of specific chemical groups, it has formed the basis of these schemes ever since. It provides an effective means of killing overwintering pupae which have been exposed to selection pressure towards the end of the season. Pupae busting has been carried forward into RMPs for Bt cotton, beginning with Ingard in 1996, and then Bollgard II. Many in the industry might consider it almost sacrilegious to suggest removing it. Yet many growers dislike pupae busting. It costs money - Cotton CRC economists have estimated a cost of $26 per hectare in fuel, labour and depreciation. More significantly, it interferes with farming systems. It is incompatible with minimum tillage, which is widely adopted in dryland farming systems and brings many benefits in reducing soil erosion, conserving soil moisture and improving carbon sequestration. These issues are most pressing for dryland cotton growers, since irrigated growers often have to perform operations in normal ground preparation which serve the purpose of pupae busting, especially for back-to-back cotton crops. Yet even for irrigated growers, the need to pupae bust can often restrict rotation crop options, and prolonged wet weather can expose growers to the risk of being non-compliant with RMPs, triggering impositions such as additional refuge planting in the next season.

Widespread adoption of Bt (Bollgard II) cotton has led to a dramatic reduction in insecticide use in Australian cotton. CSIRO research has shown that Bt cotton does not affect the survival of most beneficial species, and their numbers are higher in comparison with conventional cotton because of the reduction in insecticides. But can we be sure these beneficials are still doing the same job in controlling pests in Bt cotton? Do we know their behavioural patterns and prey consumption rates are similar in Bt compared to conventional cotton? Some preliminary experiments by PhD student Habibullah Bahar (Figure 1) and his supervisors at the University of New England indicate that at least one beneficial, the green lacewing 'Mallada signata', is still doing the job in Bt cotton.

There is considerable global interest in using recycled organic materials because of perceived benefits to soil health and environment. However, information on the effects of organic waste products and their optimal application rates on the quality of heavy clay soils such as Vertisols is sparse. An incubation experiment was therefore conducted using five organic amendments at various rates to identify their optimal application rates, which could improve the quality of the Vertisol. Cotton gin trash, cattle manure, biosolids (dry weight basis 7.5-120 t/ha), chicken manure (dry weight basis 2.25-36 t/ha) and a liquefied vermicast (60-960 L/ha, volumetric basis) changed the soil chemical, physical and microbiological properties compared with a control where no amendments were applied, viz. higher light fraction of organic matter, nutrient content (N and P) and soil microbial activity. Higher application of chicken manure resulted in an increase in dry-sieved mean weight diameter. Increasing rates of cattle manure increased exchangeable Na concentration and ESP. Although vermicast itself did not contribute a significant amount of N into the soil, when applied at higher rates (60-960 L/ha), its application resulted in increased concentration of NO₃-N in soil by amounts ranging from 43 to 429%. Optimal application rates for cattle manure and cotton gin trash were 30 t/ha, whereas for biosolids and chicken manure, the optimum rate was 60-18 t/ha, respectively.

In the four years since the release of Bollgard II® and the relaxation of the cap limiting the area of Bt cotton (Fitt & Wilson 2005) there have been significant changes to pest management in cotton. Widespread adoption of Bollgard II® (>85% of the area; Pyke in press) and improved efficacy compared to Ingard® have resulted in an 85% reduction in insecticide use. Bollgard II® crops currently receive less than one spray per hectare for Helicoverpa spp, compared with 7-11 in conventional crops (Figure 1). Here we review the current trends in pests and pest management in the current cotton system, highlight challenges, report on new tools to help manage pests and finally discuss the implication of climate change for IPM in cotton.

An integrated active optical, and passive thermal infrared sensing system was deployed on a low-level aircraft (50 m AGL) to record and map the simple ratio (SR) index and canopy temperature of a 230 ha cotton field. The SR map was found to closely resemble that created by a RapidEye satellite image, and the canopy temperature map yielded values consistent with on-ground measurements. The fact that both the SR and temperature measurements were spatially coincident facilitated the rapid and convenient generation of a direct correlation plot between the two parameters. The scatterplot exhibited the typical reflectance index-temperature profile generated by previous workers using complex analytical techniques and satellite imagery. This sensor offers a convenient and viable alternative to other forms of optical and thermal remote sensing for those interested in plant and soil moisture investigations using the 'reflectance index temperature' space concept.

In 2009 we registered product (Magnet®) containing a mixture of plant volatile attractants, a feeding stimulant and various excipients, for the control of Helicoverpa spp. and other noctuid moths in Australia on cotton, corn and beans. We believe this to be the first sprayable attract-and-kill formulation using plant volatiles to obtain registration anywhere in the world. Farmers add small quantities of any of three insecticides prior to application, which can be either aerial or ground-based. Magnet® was used on up to 50% of the acreage of conventional cotton, and substantial area-wide impacts on Helicoverpa spp. abundance were obtained. However, in recent years Australian cotton has been dominated by transgenic insect-resistant varieties which do not need protection from Helicoverpa spp. and this has greatly reduced the market for the product. We will describe studies aimed at developing applications for plant volatile based attract-and-kill for other species in other crops, including some from families other than Noctuidae. We will also describe our experiences with the Australian regulatory system, and the implications for registration of similar formulations, and we will discuss the impact of such formulations on non-target insects, including honey bees.

We investigated whether the transgenic Bt cotton influenced the foraging behaviour of a generalist predator (green lacewing larvae: 'Mallada signata' Neuroptera: Chrysopidae) on 'Helicoverpa armigera' eggs or neonate larvae in presence of aphid ('Aphis gossypii' Homoptera: aphididae). Experiments were conducted on whole single plants in cabinets or greenhouse cubicles with control over environmental variables at the University of New England, Armidale, Australia. Bt and conventional cotton plants were infested with aphid nymphs or 'H. armigera' (eggs or larvae) or both. In treatments with lacewings, two 4-day old lacewing larvae were released onto each plant. Observations of lacewing activity (resting, searching or feeding) and position (upper side of leaf, lower side of leaf, stem, petiole, square, flower or boll) were recorded over three periods (morning, noon and afternoon) each day for three consecutive days using a laptop computer (Noldus R software Wageningen University, The Netherlands). In all cases green lacewing larvae spent the largest portion of their time on the lower surface of leaves (26-60%) followed by fruit buds (cotton squares) (20-22%). In growth cabinet experiments searching was the most common activity (53%) followed by resting (40%) and feeding (7%), however, in green house cubicles, resting was the most common activity (68%) followed by searching (27%) and feeding (5%). But there was no significant difference in activity between transgenic Bt or conventional cottons in these studies. Overall, Bt cotton plants exerted no significant effect on the foraging behaviour of green lacewing.

We compared the survival of 'Helicoverpa armigera' (Hübner) (Lepidoptera: Noctuidae) eggs and larvae on Bt and conventional cotton, in the presence or absence of the generalist predator, green lacewing larvae, 'Mallada signatus', (Schneider) (Neuroptera: Chrysopidae). In small arenas, green lacewings consumed a similar number of 'H. armigera' eggs (ave. 15.8 ± 1.3 on conventional, 12.6 ± 1.4 on Bt cotton per predator over 24 h) and larvae (ave. 6.8 ± 0.7 conventional, 6.5 ± 0.8 Bt per predator over 24 h) whether on Bt or conventional cotton leaves. Likewise, similar numbers of eggs were consumed by each lacewing larva searching whole plants of either Bt (ave. 15.5 ± 0.6 of 49 over 24 h) or conventional (ave. 13.6 ± 1.1 of 49 over 24 h). On conventional plants over 72 h, survival of 'H. armigera' larvae was 72.8% and decreased to 37.7% when lacewings were present, giving a net consumption rate of 35.1% (8.6 prey per predator over 72 h). On Bt cotton plants, 13.6% of the 'H. armigera' larvae survived after 72 h and this decreased to 1.7% when lacewings were present. This combination of mortality factors operated synergistically. 'Helicoverpa armigera' larvae moved to fruiting structures on conventional or Bt cotton but failed to survive in the squares (young flower buds) when the impacts of Bt and lacewings were combined. The removal of first to second instar 'H. armigera' larvae from squares of Bt cotton by predators has the potential to reduce immediate pest damage and, perhaps more importantly, remove potentially Bt-resistant genotypes.

Four types of pheromone traps were tested for 'Heliorhis armiger' in cotton at Moree. N.S. W. The Texas trap was found to be the most efficient, catching on average 10 times more moths than other designs on the same nights.

Background: Two-spotted spider mites ('Tetranychus urticae' Koch) oviposit near leaf veins or in leaf folds on the undersides of cotton ('Gossypium hirsutum' L.) leaves where the humid boundary layer offers protection from desiccation. The authors predicted that the boundary layer of glabrous cotton leaves should be shallower than that of hairy leaves, providing some resistance to mites. The dynamics of mite populations, leaf damage, leaf gas exchange and crop yield on two leaf hair isolines (smooth versus hairy) in two genetic backgrounds was assessed. Results: Mite colonies developed faster on the hairy leaf isolines, but leaf damage per mite was higher in smooth leaf isolines, indicating more intense damage. A 50% reduction in photosynthesis on the hairy isolines required 1.8 times more mites than smooth leaves. The yield of cotton was reduced in + mite treatments, but the magnitude of reduction was similar for hairy and smooth isolines. Conclusion: Paradoxically, the relative inhospitality of glabrous leaves may have induced mites to concentrate in protected leaf sections, causing more localised and more severe damage, negating the yield benefits from fewer mites. These results highlight interactions between leaf microenvironment, pest behaviour and plant productivity that may have implications for other instances of plant resistance.

Low responsiveness of cotton to P fertilizer application on soils with low soil-test P values indicates that cotton might take up P from stable P pools. The ability of cotton to acquire P from sparingly soluble P sources was examined by comparing with wheat and white lupin. The plants were grown in washed river sand, with P sources applied at a rate of 40 mg P kg⁻¹, as sparingly soluble AlPO₄, FePO₄, or hydroxyapatite. Cotton was inefficient in accessing P from any of the sparingly soluble P sources. Thus, the low responsiveness of cotton to P fertilizers could be attributed to factors other than efficient P acquisition from the stable P pool in the soil. In contrast to white lupin which accessed little P from the sparingly soluble P sources in this study, wheat showed an outstanding ability in utilizing AlPO₄. When compared with the control, total uptake of P from AlPO₄ by wheat was approximately 9 times higher than cotton and 7 times higher than white lupin, which was possibly related to its high root Al concentration and high root:shoot ratio. The study concludes that the three species differed substantially in P acquisition from the sparingly soluble AlPO₄, with cotton being least efficient and wheat most efficient.

Research using the critical period for weed control (CPWC) has shown that high-yielding cotton crops are very sensitive to competition from grasses and large broadleaf weeds, but the CPWC has not been defined for smaller broadleaf weeds in Australian cotton. Field studies were conducted over five seasons from 2003 to 2015 to determine the CPWC for smaller broadleaf weeds, using mungbean as a mimic weed. Mungbean was planted at densities of 1, 3, 6, 15, 30, and 60 plants m⁻² with or after cotton emergence and added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 degree days of crop growth (GDD). Mungbean competed strongly with cotton, with season-long interference; 60 mungbean plants m⁻² resulted in an 84% reduction in cotton yield. A dynamic CPWC function was developed for densities of 1 to 60 mungbean plants m⁻² using extended Gompertz and exponential curves including weed density as a covariate. Using a 1% yield-loss threshold, the CPWC defined by these curves extended for the full growing season of the crop at all weed densities. The minimum yield loss from a single weed control input was 35% at the highest weed density of 60 mungbean plants m⁻². The relationship for the critical time of weed removal was further improved by substituting weed biomass for weed density in the relationship.

Field studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m⁻². Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m⁻². High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m⁻², respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

We discuss the principles of bisexual attract-and-kill, in which females as well as males are targeted with an attractant, such as a blend of plant volatiles, combined with a toxicant. While the advantages of this strategy have been apparent for over a century, there are few products available to farmers for inclusion in integrated pest management schemes. We describe the development, registration, and commercialization of one such product, Magnet®, which was targeted against 'Helicoverpa armigera' and 'H. punctigera' in Australian cotton. We advocate an empirical rather than theoretical approach to selecting and blending plant volatiles for such products, and emphasise the importance of field studies on ecologically realistic scales of time and space. The properties required of insecticide partners also are discussed. We describe the studies that were necessary to provide data for registration of the Magnet® product. These included evidence of efficacy, including local and area-wide impacts on the target pest, non-target impacts, and safety for consumers and applicators. In the decade required for commercial development, the target market for Magnet® has been greatly reduced by the widespread adoption of transgenic insect-resistant cotton in Australia.We discuss potential applications in resistance management for transgenic cotton, and for other pests in cotton and other crops.

Our research group, in collaboration with a small Australian-based company, has developed an attracticide (Magnet®) for 'Helicoverpa' moths, that has been recently registered for cotton, beans and sweet corn in Australia. We first screened a number of host as well as non-host plants of 'Helicoverpa' spp. in the laboratory using a two-choice olfactometer to identify plant volatiles attractive to the moths. The majority of the plants tested were significantly attractive to male and female moths, with the Australian natives, 'Angophora floribunda' and several 'Eucalyptus' species being the most attractive plants. Volatile profiles of these plants were determined by GC-MS. Synthetic equivalents of plant volatiles were then tested in the olfactometer singly or in combination as blends. Volatile blends consisting of floral and green leaf compounds were more attractive to moths compared with individual volatiles. For a polyphagous species like 'Helicoverpa armigera', we proposed an approach of "super blending" of volatiles that were in common between attractive plants, rather than mimicking the blend of plant odours emitted by a particular attractive plant. Field wind tunnels and traps were used to test candidate blends in the field. Small-scale field trials on various crops were conducted to determine the efficacy of a five-component blend combined with a small amount of toxicant. Field trials were also conducted to determine its effects on non-target organisms. Commercial trials in cotton demonstrated substantial reductions in heliothine numbers not only in the Magnet®-treated field but also in nearby untreated fields.

Elsewhere in this conference (Del Socorro et al.) we describe the development of an attracticide (Magnet®) for heliothine moths, which is based on plant volatile compounds. In this paper, we explore the regulatory and commercial aspects of this development.

Experiments were done to study the compatibility of a general predator, a green lacewing, to control 'Helicoverpa armigera' eggs and larvae with transgenic Bt cotton. Bt cotton did not affect green lacewing performance. Green lacewings consumed statistically identical numbers of 'Helicoverpa' eggs and larvae on both Bt and conventional cotton plants. On Bt cotton plants 83% of the 'H. armigera' larvae died within 72 hours. Mortality increased to 98% when lacewing larvae were present. This 'mopping-up' of surviving 'Helicoverpa' on Bt cotton by lacewing larvae has the potential to reduce immediate pest damage but perhaps more importantly remove potentially Bt-resistant genotypes.

Over 85% of the Australia cotton crop is transgenic, expressing Bt genes for the control of the key pests 'Helicoverpa armigera' and 'H. punctigera'. Using Bt cotton has reduced the number of pesticide applications, paving the way for a more concerted effort with integrated pest management (IPM), especially enhancing the impacts of natural enemies. There is field evidence that Helicoverpa larvae are surviving on Bt cotton. This study examines the predatory performance of a generalist predator, the green lacewing ('Mallada signata' (Schneider)) feeding on H. armigera eggs and larvae on Bt (Bollgard II ®) or conventional cotton. Prey consumption rates on single leaves were measured under laboratory conditions in small arenas. Prey consumption rates on whole plants of Bt and conventional cotton varieties were investigated in controlled environment cabinets. H. armigera eggs or larvae were distributed evenly across seven plant positions; the stem, petioles, squares, flowers, bolls and upper and lower sides of leaves. Two, four-day-old, lacewing larvae were released and surviving Helicoverpa eggs and larvae recorded after 24 for H. armigera eggs and 72 hours for 'H. armigera' larvae experiments. In the small arenas, lacewing larvae fed on similar numbers of 'H. armigera' eggs (ave. 15) or larvae (ave. 8) whether searching Bt or conventional cotton leaves. Likewise, similar numbers of eggs were consumed by lacewing larvae searching whole plants of either Bt (ave. 15) or conventional (ave. 14) varieties in 24 hours. On whole Bt cotton plants 83% of the 'H. armigera' larvae died. Mortality increased to 98% when the two lacewing larvae were present. Lacewings on conventional cotton consumed 65% of the prey. This 'mopping-up' of surviving Helicoverpa on Bt cotton by lacewing larvae has the potential to reduce immediate pest damage but perhaps more importantly remove potentially Bt-resistant genotypes.

Introduction: The native budworm, 'Helicoverpa punctigera' (Wallengren), is a serious pest of cotton and many other field crops in Australia. Daisies and native legumes are important sources of 'H. punctigera' moths in the semi-arid regions of inland Australia. Early studies on the ecology of 'H. punctigera' in inland Australia in the mid-1980's to mid-90's suggested that moths emerging in early spring from the inland migrate on strong north-westerly winds that accompany the passage of cold fronts, towards the cropping areas in the south and east of the continent. This spring migration has been considered to be the key ecological reason why this species has not developed resistance to insecticides. However, recent resistance monitoring in transgenic cotton demonstrated temporary increases in the frequency of alleles conferring resistance to the Cry2Ab toxin in 'H. punctigera'. Methods: Since 2009 we continued the long-term monitoring of 'H. punctigera' populations in south-western Queensland, and recently, in inland South Australia, through a network of pheromone traps and host plant and larval surveys, to determine whether the spring migration system in 'H. punctigera' has changed and what factors might have contributed to this change. Results/Conclusion: An overview of the population dynamics of 'H. punctigera' in inland Australia will be presented. Our pheromone trapping data for non-cropping regions in inland Australia contribute to a forecasting system for 'H. punctigera' migration to south-eastern Australia during spring, which is initiated by CESAR Australia in collaboration with other organisations providing data for cropping regions in eastern Australia.

The native budworm 'Helicoverpa punctigera' is an important pest of field crops in Australia alongside the cotton bollworm 'Helicoverpa armigera', and both share a number of host plants. 'H. punctigera' moths are known to migrate into cropping regions, from inland Queensland, Western Australia and South Australia but multi-year weather perturbations such as the Millennium drought may have reduced migration from drought-stricken areas in inland Queensland. Resistance management in Bt cotton may be at risk from reduced migration as migrants dilute any resistance genes that might be present in 'H. punctigera' that have been exposed to Bt toxins. In southeast Australia 'H. punctigera' appears to be becoming more abundant later in the cotton growing season, and thus, the overwintering ecology of 'H. punctigera' needs to be re-examined. Laboratory studies were conducted under a range of temperatures and photoperiods to determine under what conditions diapause occurs in 'H. punctigera', and to compare the results with similar published studies. At 25°C the least amount of diapause was induced at 14L:10D, and the highest percentage of diapause at 12L:12D. Temperatures of a constant 19°C or cooler produced the highest percentages of diapause, even under a summer 14L:10D photoperiod. At 12L:12D photoperiod the highest percentages of diapause were induced at temperatures below 19°C. Larvae and pupae moved from 25°C to 19°C showed an increase in diapause levels while larvae moved from 19°C to 25°C did not. A statistical model was created from my data, showing the significant effects of temperature, photoperiod, and photoperiod-temperature interaction on diapause induction.

The contribution of non-cultivated areas to Heliothis spp. populations, and the roles of these areas in the ecology of the species, have been little studied in Australia. Zalucki et aL ( 1986) found at least 183 publications related to H. punctigera and H. armigera during the 30 years to 1986. There were 112 which dealt with specific crop hosts, but only 3 which included non-cultivated hosts. This balance no doubt reflects the priorities of organisations responsible for research on Heliothis spp. in the past, which have of necessity been parochial. The difficulty is that with pests which are highly polyphagous and migratory (Zalucki et aL 1986, Farrow and Daly 1987), such neglect means that we lack understanding of how they are adapted to the Australian environment. Consequently our ability to manage them is limited. In this paper I review recent work in non-cultivated areas and suggest directions for future research.

This study was focused on the effect of environmental and host factors on the antagonism of Fusarium wilt of tomato, caused by Fusarium oxysporum f. sp. lycopersici (Fol), by non-pathogenic strains of F. oxysporum. Seven non-pathogenic strains of F. oxysporum were isolated and screened for antagonism of Fusarium wilt. Strains F1 and F4 were chosen for further experiments as they reduced disease severity more than other non-pathogens. The best method for applying non-pathogens and pathogens was to inoculate soil with conidial suspension. The non-pathogens reduced seed germination and growth of tomato plants in the absence of the pathogen. In a split root system, non-pathogens F1 and F4 induced resistance of tomato plant against Fusarium wilt although there was no direct contact between the pathogen and non-pathogens. Iron at high and standard concentration in the nutrient solution stimulated induced resistance. However, direct antagonism of Fol by F4 was greatest at low level of iron.
Tomato root exudates increased in the vitro antifungal activity of non-pathogens toward pathogens and also increased spore germination of both non-pathogens and pathogens. The components of root exudates including sugars and organic acids influenced the antagonism of non-pathogens against pathogen in vitro. However sugars and organic acids had little effect on disease suppression in pot trials.
In dual culture, using NaNO3 as source of N, the inhibition of Fol by F1 and F4 was decreased at high level of N, whereas at high level of NaNO3 as source of N the antibiotic production increased. Using NH4Cl as source of N at high and low level, the inhibition of Fol by F1 and F4 was increased and the antibiotic production of non-pathogens also increased. In pot trials, the disease severity was less at low N compared with high level of N.
In dual culture, at low level of K the antagonistic activity of s F1 and F4 against Fol was improved. However, at high level of K, the antibiotic production of non-pathogens increased. In glasshouse pot trials, non-pathogens improved plant health at low level of K, whereas the growth of non-pathogens was decreased at high level of K.
At high level of Ca, the inhibition of growth of Fol by F1 and F4 was decreased. Also at low level of Ca the inhibition of growth of Fol by antibiotic production of F4 was increased. However, the inhibition of growth of Fol by antibiotic production of F1 was increased at high level of K.
The inhibition of growth of Fol by F1 and F4 was decreased with high level of iron. The antibiotic production of F1 and F4 inhibited growth of Fol at low level of iron more than at high level. Biological control did not work well at high levels of iron.
Further work is needed on the effect of non-pathogens on the growth of plants. More tests should be done on the effect of root exudate on antagonism. Biocontrol agents should be found that can work well at low nutrient levels.

Soil sodicity is widespread in the cracking clays used for irrigated cotton ('Gossypium hirsutum' L.) production in Australia and worldwide and sometimes produces nutrient imbalances and poor plant growth. It is not known whether these problems are due primarily to soil physical or to soil chemical constraints. We investigated this question by growing cotton to maturity in a glasshouse in large samples of a Grey Vertosol in which the exchangeable sodium percentage (ESP) was adjusted to 2, 13, 19, or 24. A soil-stabilising agent, anionic polyacrylamide (PAM), was added to half the pots and stabilised soil aggregation at all ESPs. Comparison of the effect of ESP on cotton in the pots with and without PAM showed that, up to ESP of 19, the soil physical effects of sodicity were mainly responsible for poor cotton performance and its ability to accumulate potassium. At ESP >19, PAM amendment did not significantly improve lint yield, indicating that soil chemical constraints, high plant sodium concentrations (>0.2%), and marginal plant manganese concentrations limited plant performance. Further research into commercial methods of amelioration of poor physical condition is warranted rather than application of more fertiliser.

The egg and nymphal development, fecundity and survival of the green mirid, 'Creontiades dilutus' were examined at a range of temperatures and a modified day-degree model fitted to the data. Day degree (DD) requirements for egg and nymphal development, and threshold temperatures were calculated from the fitted lines. Female fecundity and longevity, egg and nymphal development, and survival of C. 'dilutus' were significantly influenced by temperature. Eggs and nymphs failed to complete development at temperatures below 17 and at 38°C. Females also failed to produce any eggs at 11 and 38°C. The optimum temperature range for female fecundity was found to be 26–32°C. The optimum temperature for the development of eggs was calculated from the model as 30.5°C and for nymphs as 31.5°C. The threshold temperature for development was 15.8°C for egg and 15.1°C for nymph; 69.4 and 156.7 DD were required for completing the egg and the nymphal development, respectively. At the optimum temperature, it was estimated that development from egg to adult took 15 days. Survival was highest at 26°C for eggs and at 30–32°C for nymphs.

Insecticide resistance in 'Helicoverpa armigera' (Hübner) (Lepidoptera: Noctuidae) poses a constant challenge to cotton production in Australia. This thesis focuses on resistance to two biological insecticides, pyrethrum and spinosad. Both could be highly effective insecticides if resistance in 'H. armigera' were not a problem. The purpose of this work was to investigate metabolic resistance mechanisms to pyrethrum and spinosad and to determine whether resistance could be overcome by temporal synergism using novel techniques of pre-spray synergist applications of the esterase inhibitor piperonyl butoxide (PBO).

The influence of two synthetic plant volatiles on the number of male 'Helicoverpa armigera' (Hübner 1808) (Lepidoptera: Noctuidae) caught in sex pheromone-baited traps was studied in field plots in Australia. Phenylacetaldehyde and (Z)-3-hexenyl acetate were combined with synthetic sex pheromone in traps. Generally, most males were captured in traps baited with pheromone alone and more males were captured by the mixture containing (Z)-3 hexenyl acetate than that containing phenylacetaldehyde. At the three concentrations studied, neither volatile synergised the activity of the pheromone. Traps baited with the plant volatiles alone caught very few moths of either sex.

Practical solutions to optimise nitrogen use efficiency within modern surface irrigated cotton systems in Australia may be possible by regulating the frequency of water and reducing the N applied, compared with typical current practises. A two-year study examined the effect of irrigating at three different water deficits that applied a similar total irrigation volume: >−60 kPa (HF), between −80 and −100 kPa (IF) and between −100 and −120 kPa (LF) for a period from initial flowering throughout boll development, in combination with different nitrogen fertiliser rates on the growth, yield, nitrogen use efficiency and lint quality of cotton. It was hypothesised that shorter deficits would increase N uptake, and nitrogen use efficiency compared with longer deficits caused by consistently higher soil water potentials in the root zone. The major effects of irrigation treatment on growth was to increase plant height and number of bolls, delay crop maturity and decrease micronaire. The irrigation strategy according to yield was most consistently optimised over both seasons when soil matric potential was maintained between −80 and −100 kPa (IF treatment). Lint yield was reduced by 9–13% when the irrigation deficit was <−100 kPa. The most efficient fertiliser use varied between the two years but was always lowest in the treatment with the highest deficit. Irrigation deficit did not change nitrogen uptake or internal nitrogen use efficiency. Nitrogen, even at rates substantially lower than typically used commercially, did not affect fibre quality. There was no interaction between irrigation strategy and N fertiliser rate on yield, fibre quality and fertiliser use efficiency.