ESTIMATING THE LEVEL OF FRUIT SCARRING BY CITRUS THRIPS FROM TEMPERATURE CONDITIONS PRIOR TO THE END OF BLOOM

In this study, we develop and validate multiple regression models to e stimate the degree of fruit scarring by citrus thrips, Scirtothrips ci tri (Moulton), from heat and chill degree days. Regression coefficient s indicate that cool weather during early March (2 March-16 March) and warm weather during bloom are associated with high levels of thrips s carring. The biological mechanisms leading to the temperature-fruit sc arring relationships are unknown. An economic analysis suggests that u sing model predictions may increase the average financial return per h ectare and reduce the number of insecticide treatments applied against citrus thrips. (C) 1997 Elsevier Science Ltd.