危害苹果的早期落叶病,主要包括褐斑病、灰斑病和轮斑病,其中以褐斑病危害最重。褐斑病在全省苹果产区都有发生,分布很广,是造成苹果大小年现象的重要原因之一。一、症状 1、褐斑病。主要危害叶片,也能侵染果实。叶片初发病时,在叶片正面出现红褐色至紫褐色小斑点或深褐色小泡疹。单生或数个连生。以后小斑点或泡疹呈褐色,随病情进展及发病早晚,症状可演变为多种类型。主要有三种:①同 Harm the early deciduous apple diseases, including brown spot, gray spot disease and leaf spot disease, of which the brown spot is the most dangerous. Brown spots in the apple producing areas across the province have occurred, is widely distributed, is an important reason for the size of the apple caused by one of the reasons. First, the symptoms 1, brown spot disease. The main hazard leaves, but also can infect the fruit. The initial onset of leaves, leaves appear in front of the reddish brown to purple-brown spots or dark brown small bubble. Single or several even students. Small spots or brownheads later brown, with the disease progression and onset sooner or later, the symptoms can evolve into many types. There are three main: ① the same