Abstract: Trifolium pratense cv. Minshan,an excellent legume forage,is suitable for growing in Min County,Gansu Province. Previous investigations have found that red clover suffered serious yield losses due to field diseases. However,systematic studies on the effects of diseases on performance of the plant remained unclear. This study aimed to investigate the major diseases and their occurrence patterns in the fields. Additionally,the study examined the impact of Stemphylium leaf spot disease on the growth and quality of red clover. The main field diseases were Stemphylium leaf spot,Leptosphaerulina leaf spot,and Longiseptatispora leaf spot,caused by Stemphylium sarcniforme,Leptosphaerulina trifolii,and Longiseptatispora meliloti,respectively. Among them,Stemphylium leaf spot had the highest severity,with a peak incidence rate of 26.67% and a disease severity index of 8.20 and caused a 20.14% reduction in fresh weight,a 20.93% decrease in chlorophyll content,and various changes in nutritional indicators. Stemphylium leaf spot had a significant impact on the growth and quality of red clover. This study provided a clear understanding of major diseases occurring in red clover fields in Min County,particularly the impact of Stemphylium leaf spot on the growth and quality. The findings provided valuable insights for disease prevention and control of red clover cultivation in this region.

Key words: Trifolium pratense cv. Minshan, Filed disease, Pathogenicity, Growth indexes, Pasture quality

摘要： 岷山’红三叶(Trifolium pratense cv.Minshan)是适宜于岷县地区生长的优良豆科牧草品种。前期的调研发现该地区红三叶田间病害发病较重，限制了红三叶的生产，而目前尚缺少该地区病害的系统研究。本研究调查了'岷山’红三叶在岷县田间的主要病害及发生规律，并研究了匍柄霉叶斑病对红三叶生长和品质的影响。该地区红三叶主要田间病害为匍柄霉叶斑病(Stemphylium sarcniforme)、小光壳叶斑病(Leptosphaerulina trifolii)和长隔孢叶斑病(Longiseptatispora meliloti)。其中红三叶匍柄霉叶斑病最为严重，最高发病率26.67%，病情指数8.20。匍柄霉叶斑病显著影响了红三叶的产量和品质，导致鲜重显著下降20.14%、叶绿素含量显著下降20.93%及引起各项营养指标的不同变化。本研究明确了岷县地区红三叶主要病害的发生情况及发病最为严重的匍柄霉叶斑病对红三叶生物量和品质的影响，为该地区的红三叶病害防控提供依据。

关键词: 岷山’红三叶, 田间病害, 致病性, 生长指标, 牧草品质