| Sumario: | Snap bean yield losses caused by the Trialeurodes vaporariorum-Thrips palmi complex were measured in three experiments conducted in the Pradera region of the Cauca Valley (Colombia) at an altitude of 980 m above sea level and 23 degrees C. The first two trials had an experimental design of randomized complete blocks with four repetitions and six treatments. Treatments were differential chemical control regimes so that potential losses caused by thrips, by whiteflies and by the complex could be measured. Residual and marginal losses were also measured. A 4 x 4 latin square design was used In a third trial in which an absolute check was compared with whitefly and thrips control, whitefly control, and thrips control. In the first two trials mean potential losses due to the whitefly-thrips complex were 44.5% (range: 39-53%); losses due to thrips averaged 28.4% (range: 25-35%); the whitefly caused average losses of 16% (range: 14-18%). In the third trial, losses caused by the whitefly-thrips complex, by thrips alone and by the whitefly alone averaged 47.4, 30.9 and 16.5%, respectively. Residual losses (those incurred by the farmer following his own methods of control) were 14% (range: 8-22%). Marginal losses (those occurring when an action threshold for whiteflies is used) averaged 27% (range: 23-33%).
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