梨园喷撒杀螨剂的最佳时机是,平均每片梨树叶上有1～2个螨类害虫的时候。用药过晚,螨类害虫会数量增加,果树叶上虫卯的数量也会增多;药物可以杀死大量螨类成虫,但对虫卵往往收不到预想的效果,随着药效的消失,虫卵中孵化出了幼虫,又来吸食梨树的叶子。如果在梨园中过早使用杀螨剂,又会使螨类害虫产生抗药性。怎样确定喷撒杀螨剂的最佳时机呢?方法很简单,通过调查梨园中的50片叶子,便可找到最佳时机。具体做法是,根据果园占地的几何图形,首先选择一条果园的对角线,在这线的不同点上取叶检查,共取50片叶子,每一处取叶点可摘取2～3片叶子(取叶点与取叶点之间的距离应尽量相等)。对取下的样叶,用放大镜检查叶子背面有无螨类害虫,把检查结果记录下来。如果不用放大镜,用白纸也可以进行检查——把白纸放在手掌上,再把果树叶放在白纸上,让叶子的正面向上,然后用手按压叶 The best time to spray acaricide in pear orchard is when there are 1 or 2 mite pests per leaf on average. Medication is too late, mites will increase the number of pests, the number of insects on the leaves will increase the number of fruit; drugs can kill a large number of mites adults, but the eggs are often not expected to receive the effect, with the disappearance of efficacy, Eggs hatch out of larvae, but also to absorb the leaves of pear tree. If used too early in the pear garden acaricide, mites pests will cause resistance. How to determine the best time to spray acaricide? The method is very simple, through the investigation of 50 leaves in the pear garden, you can find the best time. Specifically, according to the geometry of the orchard, first select the diagonal of an orchard, take a leaf check at different points of the line, take a total of 50 leaves, take leaves 2 to 3 Leaf (take the distance between leaves and take leaves should be as equal as possible). On the removal of the leaves, with a magnifying glass to check the back of the leaves without mite pests, the test results recorded. If you do not use a magnifying glass, use white paper can also be checked - the white paper on the palm of your hand, then put the fruit leaves on white paper, so that the leaves face up, and then press the leaves by hand