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Résumé :
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In Denmark, farmers are recommended to spray against aphids in spring barley fields at very low densities. Moreover, about 50% of the spring barley fields are treated with insecticides annually, when only about 25% need this control. In order to develop a more realistic method to determine the control threshold, spring barley field trials were carried out between 1985 and 1998. The thresholds is expressed as aphid-days, which is defined as the number of aphids per tiller multiplied by the number of days they are present. A control threshold of 105 aphid-days was found which corresponds to a traditional control threshold at about 10 aphids/tiller. By using this new threshold, the application of insecticides could be lowered significantly, due to a more dynamic and effective way of describing control threshold. (C) 2000 Elsevier Science Ltd. All rights reserved.
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