In order to understand the severity of the apple valsa canker Valsa ceratosperma in Yantai of Shandong Province, 21 commercial orchards located in Qixia, Haiyang and Laiyang were investigated in the spring of 2011. The results showed that apple valsa canker occurred seriously in the area in the spring of 2011. The incidence of diseased trees with new canker scars was 68.20% and the ratio of dead trees caused by the disease was 2.76%. The mean ratio of harmed and dead one-year-old branches, the most important measurement of apple tree growth, were 23.98% and 10.74%, respectively. The orchards with more than 50% diseased trees occupied about 25%—30% of all orchards examined. In the investigation, 967 new canker scars and 2.32 canker scars per apple tree on average were observed. Among them, 80. 04% canker scars were developed from pruning wounds and 60.29% from former old scars. Long-period raining in the autumn of 2010, low temperature in the winter of 2010 and severe drought in the spring of 2011 were the most possible reasons causing the outbreak of apple valsa canker in the spring of 2011 in the area. The results also indicated that pruning wounds were the main entrances of V. Ceratosperma infection, and recurrence of old scars was the main reason for spring cankering.%为了解2011年烟台苹果产区腐烂病的发生情况,2011年5月,在腐烂病发病较重的栖霞、海阳等地选择21个农户的果园,对腐烂病的发生情况进行了调查.结果表明,21个果园中具有新病疤的病株率为68.20％,死株率为2.76％,平均受害枝量为23.98％,死枝量10.74％,病株率超过50％的果园占25％～30％,总体发病情况比一般年份严重.调查共发现967块新病疤,平均每株2.32块,其中源自剪锯口的病疤占80.04％,从旧病疤复发的病疤占60.29％.2010年秋季的连续阴雨、冬季低温和2011年春季干旱可能是导致烟台苹果产区2011年春季腐烂病大发生的主要原因.剪锯口是腐烂病菌侵染的主要途径,旧病疤复发是春季腐烂病发病的主体.
展开▼
