一、杨树破腹病的症状特征:主要危害树干,有时危害较大骨干枝。通常是从树干平滑处开裂,表皮层先裂,裂缝可深达木质部,第二年春季树木萌动后自伤口流出树液,干后呈铁锈色。树势壮且危害轻者伤口可自然愈合。一般被害后裂缝都逐年加深加长,有时长达3～4米。从被害状上看,大体上分为两种类型,一是开放型,开裂后愈伤组 First, poplar broken belly symptoms of the symptoms: the main harm to the trunk, and sometimes endanger the larger branches. Usually from the smooth trunk crack, the epidermis first crack, the cracks can be deep as the xylem, the second spring after the tree sprout from the wound after germination, dry rusty color. Tree strong and harm light wounds can heal naturally. After the general crack are deepened and lengthened year by year, sometimes up to 3 to 4 meters. From the victim state, generally divided into two types, one open, crack callus