苹果轮纹病菌对戊唑醇的敏感性及其抗性突变体的致病力

为明确苹果轮纹病菌对戊唑醇的敏感性及其抗性突变体的致病力,采用菌丝生长速率法测定了130株苹果轮纹病菌菌株对戊唑醇的敏感性,采用药剂驯化和紫外线诱导的方式获得抗性突变体,并研究其生存适合度。结果表明,戊唑醇对130个菌株的EC50分布在0.051 6~1.925 4μg/mL,均值为(0.799 6±0.039 1)μg/mL,表明苹果轮纹病菌开始出现敏感性下降的亚群体。供试苹果轮纹病菌菌株的抗性频率为71.54%,各省份均未出现高抗菌株。药剂驯化、紫外诱导共获得3株抗性倍数分别为58.82倍、41.60倍、38.19倍的高抗菌株。抗性突变体致病力、适合度指数与敏感菌株相比没有显著性差异。无药培养9代后,各抗性突变体EC50逐渐下降,所获抗性可能不能稳定遗传。表明苹果轮纹病菌对戊唑醇的抗性在田间自然选择压力下可能会逐渐降低。

Susceptibility of Botryosphaeria dothidea to tebuconazole and virulence of its resistant mutants

Aceria pallida Keifer has been a major pest mite of Lycium spp. in the main wolfberry produce area of northwest China. The distribution of galls induced by A. pallida in wolfberry canopy was investigated and its effects on host plants were also estimated in Tuoketuo County, Inner Mongolia. The results showed that A. pallida tended to damage twigs in northwest direction heavily. In middle and late periods of plant growth of the year, most of the galls located in the middle and upper twigs in plant canopy generally and preferred the tender leaves at the end of twings. The galls had a diameter of 1 mm to 7.5 mm, which presented normal distribution, and 2 mm to 4 mm were in the majority. The quantity of live mites was positively correlated to the size of gall when its diameter was less than 4 mm, while negatively correlated when the diameter was more than 4 mm. Comparing to the normal individual, the length, width and area of damaged leaf were smaller, the vertical diameter, transect diameter and dried weight of wolfberry were lighter as well as. The length, width, leaf area and dried weight of wolfberry from damaged individuals approximately reduced by 25%, 50% and 11.5%, respectively.