长期以来,有的果农不懂科学管理往往是在果树害虫的防治上采取有虫就喷药的办法,还认为这种办法最保险。但是,此做法在虫口密度较低时,将仅有的几头害虫杀死,其结果一方面使天敌失去食物,降低了自然界对害虫的控制力,另一方面因喷药所付出的经济代价远远超出了所保护下来的果品价值,可谓得不偿失,此时就不应进行防 For a long time, some farmers do not understand scientific management is often insecticide in the pest control of fruit trees to take the approach, but also that this approach is the most insurance. However, this method kills only a few pests when the population density is low, which on the one hand loses its natural enemies and reduces the control of pests in nature. On the other hand, the economic cost of spraying pesticides Far beyond the value of the fruit preserved, can be described as worth the candle, at this time should not be anti