Prospects for a Sustainable Cotton Industry in Tropical Australia Using Novel Crop and Pest Management

Previous attempts, to grow cotton in the Ord River Valley region of tropical North Western Australia between 1963 – 1974 during the summer wet season failed due to a combination of crop management problems and high levels of insecticide resistance in Helicoverpa armigera. This paper describes a multi-disciplinary approach to research which aims to re-establish a sustainable industry using a novel management system. Components of the system include a shift to dry season (winter) cropping and a resistance management strategy, comprising the use of refugia crops for beneficial insect conservation and judicious use of selective insecticides. Pest management research focused on developing integrated pest management systems to complement transgenic cultivars expressing the Cry1A(c) delta-endotoxin from Bacillus thuringiensis (Bt). Control of the key pests, Helicoverpa spp, was greatly assisted by Trichogramma pretiosum which frequently parasitised more than 70% of eggs oviposited. Other lepidopteran pests were controlled successfully by Bt expression in the plants. Agronomic research investigated the effects of a winter growing season on crop development, yield and fiber quality. Over three seasons experimental yields for the top 10 cultivars averaged 2043 kg lint/ha, similar to the average summer grown experimental yields of 2069 kg lint/ha in temperate Australia. Cool night temperatures reduced fiber length by 1.27 2.54 mm (0.05 0.10 inches) at the optimum March-April sowing period compared with other sowing dates and the fiber length of the same cultivars when grown under summer conditions. Early crop growth was vigorous due to high temperatures, applying mepiquat chloride prior to squaring suppressed this growth. Areas of future research are discussed.