Compensation in Cotton following pest damage: Potential and Limitations
Abstract
Damage caused by chewing and sucking pests does not necessarily lead to a yield loss in cotton. There is ample evidence indicating that cotton can fully recover from levels of vegetative and fruit damage above the current industry threshold. The ability to compensate for tissue loss in cotton is attributed to an improved canopy development stimulated by pre-squaring tip damage, and to fruit substitution for damage and increased fruit production during the reproductive stage. However, cotton's ability to compensate for fruit loss declines dramatically as boll development accelerates (3-4 weeks after first square), therefore, a more cautious pest management is necessary for about 2 months (until cut out)to avoid yield loss. A look-up table of the estimated fruit damage caused by Helicoverpa larvae at different fruiting stages is provided to allow assessment of a crop's ability to tolerate fruitloss. To ensure full compensation, it is important to maintain a healthy crop canopy (ie. , keeping mite damage under control) but not one with excessive leaf area (which leads to yield loss), particularly during the boll forming stage. Excessive growth response to pest damage may be minimised by selecting okra leafcultivars and by managing nitrogen and irrigation properly. A well managed crop may even respond to damage such as early season tipping out with yield gain over an undamaged crop. Clearly, the potential for reduced pesticide use in early and mid-season clearly exists and so do the attendant benefits of that. Harnessing the compensatory capacity of cotton is a key component of Integrated Pest Management and sustainable cotton cropping. This research continues the effort to ascertain ways of fully utilising the compensation potential of cotton for future incorporation into decision support systems for pest management.
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- 2000 Australian Cotton ConferenceProceedings from the 2000 Australian Cotton Conference