一、山楂红蜘蛛的为害和分布在苹果树上为害严重而又发生普遍的红蜘蛛类,有山楂红蜘蛛(Tetranychus vienensis Zacher)、苜蓿红蜘蛛(Bryobia praetiosa koch)和苹果红蜘蛛(Panonychus ulmi Koch)三种。近几年来尤以山楂红蜘蛛发生更为遍,为害也较严重。苹果树被害之后,往往早期落叶,树势生长发育不良;因而影响花芽分化,致使第二年严重减产;并且被害植株由于树势衰弱,冬期还容易遭受冻害。所以山楂红蜘蛛 First, the hawthorn red spider damage and distribution In the apple tree serious damage and common occurrence of red spiders, hawthorn spider (Tetranychus vienensis Zacher), alfalfa spider (Bryobia praetiosa koch) and apple red spiders (Panonychus ulmi Koch Three kinds. In recent years, especially hawthorn spider occurred more commonly, the damage is more serious. After the apple trees were killed, they often deciduous early, the tree growth and development are poor; thus affecting the flower bud differentiation, resulting in a serious cut the next year; and the victim plants due to the weakening of the tree, the winter is also vulnerable to frost damage. So hawthorn red spider