The aims of the project are to provide a basis for sound irrigation management of cotton through studies of: � (i) Crop response to a range of irrigation management options in terms of crop irrigation efficiency (yield per unit water applied) and plant fruiting development. (ii) Soil water balance in relation to irrigation application efficiency (infiltration per unit water applied), crop water use, ground-water accessions and model predictions of all these factors.

Objectives o Determine optimum nitrogen rates for cotton under a range of conditions. o Determine the best time to apply this nitrogen. o Measure the pattern of nitrogen uptake in relation to rate and timing and hence calculate fertiliser recovery. o Examine the relationship between soil nitrate test and subsequent nitrogen extraction by a cotton crop. Measure cotton crop requirements of the trace elements zinc, copper , iron and manganese . o Measure the effects of plant spacing, temperature and light on leaf growth in cotton. o Measure the penetration of light through cotton canopies . o Map the production and survival of cotton fruit. o Use the leaf growth, light interception and fruit map data to develop simulation models for cotton . Some success was achieved in all objectives . A summary of results from the major projects follows. More comprehensive results of all topics are attached. Difficulties encountered are outlined in the projects where they occurred.

Heliothis armigera and H. punctigera are serious pests of cotton in Australia. Control of Heliothis is currently dependent on insecticides. Levels of resistance to several of the major chemical groups of insecticides is sufficient to threaten the long ter

The project utilized a field trial established by Auscott Pty Ltd, on a grey-brown clay at Warren in June, 1984. The trial consists of 3 replicates of the following treatments: 1. deep ripping to 45 cm, followed by discing and listing; 2. chisel ploughing to 25 cm, followed by discing and listing; 3. direct listing only, ie. minimum tillage.

Project objectives To determine the nature and extent of migratory flight in Heliothis Armigera and punctigera and to estimate the significance of migration in the formation of outbreaks and in the spread of insecticide resistance in these pests.

objectives of the present work are the identification of the sex pheromones of Crocidosema plebejana and Pectinophora scutigera and the testing of synthetic candidate mixtures as attractants in monitor traps in the field.

The aims of the project were: * to test various versions of SIRATAC on a commercial scale. * to provide a database of the response of cotton to damage. * to compare the response of the new varieties Siokra and DP90 with DP61. Field work consisted of large scale trials on the leased Leitch block and small plot experiments using manual disbudding to simulated pest damage. The results of these trials were integrated with data from CS16L (The response of cotton crops to damage) and CS23L (Development Officers for SIRATAC) and made available to the industry at the Australian Cotton Conference (Kelly et at 1988). Further analysis of these results has shown that the capacity of the cotton crop to compensate for early season damage depends on the yield level. At yield levels common a decade or more ago (5 to 6 bales per ha) the crop could compensate but at current yield levels (7+ bales per ha) it is unable to do so. Furthermore Siokra is more tolerant to damage than DP90. These findings have been published in a series of three papers in the Journal of Economic Entomology (Brook et a1 1992, in press) and received rave reviews from the cotton entomology community. The abstracts of these papers are attached.

Any agent which reduces damage caused by heliothis is a valuable asset. In Australia we are fortunate to have several species of native parasites which attack heliothis, but not all of them are useful for within-crop management. Some parasites kill heliothis only after the larval stage has completed feeding, so in terms of crop damage, there is no difference between parasitised and unparasitised larvae. Current research at Toowoomba is investigating a native parasite, Microplitis demolitor Wilkinson [Hymenoptera: Braconidae], that kills heliothis during the fourth instar, before causing serious feeding damage. Results are presented on some aspects of this research. The release of two exotic species with attributes similar to M. demolitor is also discussed.

Nowadays, most of us are aware that natural enemies (parasites and predators) sometimes play an important role in the control of pests attacking our crops. As sure as heliothis will infest our cotton next season, we can be just as sure that parasites and predators will be there too - if they are given a chance! The problem is that we simply don't have the confidence to rely on natural enemies because we don't know enough about them. Where the risk is high, producers understandably are reluctant to take chances, and opt for the tried and proven method of pest management - insecticides. But this situation is changing. Resistance to insecticides has developed, human safety and the environment are major concerns, insecticide costs are increasing, and so on. We don't need to dwell on these issues. Opportunities are there to develop alternative management tools, and we must embrace their prospects.

Cottongrowers in central Queensland (CQ) enjoy no advantage over southern counterparts in the range of insect pests that attack their crop. Heliothis species, rough and pink-spotted boll worms, and mirids are major pests which damage the terminal buds and fruiting structures of cotton plants, potentially causing radical loss of yield and profit. While mites and tipworm generally are less active than in the south, a wider planting window means that adult forms of the soil insects that attack early-planted cotton seedlings are available to attack late-planted ones.