Envirofeast IPM in Cotton: Part 1. Integration with Lucerne Strips to Manage Green Mirids in Cotton
The green mirid, Creontiades dilutus (Stal), is one of the key early season pests on cotton in Australia. Adults and nymphs feed preferentiality on the meristematic tissue (both apical and axillary buds) of the cotton plant (Bishop, 1980). Severe infestations cause cotton plants to lose squares and also cause damage to growing tips, resulting in significant delays in growth and maturity of the plant(Adams and Pyke, 1982; Chinajariyawong et al 1988; Khan 1995 unpublished data). This delay can lead to loss in yield and/or quality. Currently, populations of green minds in commercial cotton are suppressed by insecticide sprays (mainly synthetic pyrethroids, organophosphates, cyclodienes and carbamates) applied for helicoverpa spp. In high infestations, dimethoate is the only effective insecticide available for green mirid control. The use of these insecticides early in the season disrupts beneficial insect activity and deters any chance of a true integrated pest management (IPM) program being developed for cotton. However, with the proposed introduction of Ingard (transgenic) cotton by Monsanto in Australia by 1997/98, it is expected that synthetic insecticide use on cotton will be reduced and green mirids may assume greater importance in the Australian cotton industry as they are unaffected by the Bt toxin in these plants. Green mirid infestations of Ingard cotton may therefore require the use of synthetic chemicals for control. Chemicals will disrupt the natural enemies of cotton pests and flare mites, aphids and other pests. If these things do happen, then Ingard cotton will require the same insecticide strategy as normal cotton to manage secondary pests. However, to realise the full benefits of the Ingard technology, growers should use new management techniques for green minds which do not rely on insecticides.