一、症状及发生时期 梨黑星病主要危害叶片及果实。叶片受害,多以叶背面沿主、侧脉产生圆形或不规则形的、淡黄色病斑,其上长出一层放射状的黑霉,严重时病叶早期脱落。幼果期感病,果实变畸形,早期脱落。成长期果实受害,果面上生大小不等的圆形黑色病疤,果面粗 First, the symptoms and occurrence Pear scab disease main hazards leaves and fruits. Leaf damage, mostly along the back of leaves along the main, lateral veins to produce round or irregular shaped, yellowish lesions, which grow a layer of radial black mold, sick leaves early serious fall off. Sensitive young fruit, fruit deformity, early loss. Growing fruit damage, the fruit size of students ranging from round black scars, thick fruit surface