宁夏南部山区苜蓿褐斑病田间发生及流行动态

根据不同地带、田块和不同的刈割期,针对目前宁夏南部山区栽植的国外引进品种、地方品种进行了褐斑病Pseudopeziaz medicaginis田间发生及流行动态调查。结果表明,不同苜蓿Medicago sativa品种上褐斑病的发生程度不同,18个调查品种中,加拿大DY和耐寒苜蓿发病重,其次是美国杂花苜蓿、WL323、中首1号,固原苜蓿发病最轻,但是不同品种上病害的发生和发展趋势是相同的;褐斑病的季节消长曲线呈“S”型,5月底、6月初为病害的始发期,7、8月为盛发期,9月进入衰退期,整个生长季节中病害的增长速度以8月上中旬最快,7月下旬和8月下旬次之,7、8月是褐斑病发展的关键期。刈割措施影响病害的发生和发展。适时、合理应用刈割措施是延缓、减轻和控制褐斑病危害的有效措施。

Field occurrence and epidemic dynamics of alfalfa common leaf spot (Pseudopeziza medicaginis) in the mountain area of southern Ningxia

Field Occurrence and epidemic dynamics of alfalfa common leaf spot (Pseudopeziza medicaginis) were investigated in the exotic and native varieties at different fields and clipping times. The results showed that the occurrence degree of alfalfa common leaf spot was different with varieties, but the trends of the disease were the same. Within 18 varieties, the highest disease incidence and index were found on Canadian DY and winter hardy alfalfa, the lowest ones found on Guyuan alfalfa, and those on American Zahua alfalfa, WL323, and Zhongmo No. 1 were the middle degree. The development of the disease exhibited a "S" type curve in seasonal dynamics. The disease began from the end of May to early June, and reached up to exponential phase in July and August, and declined in September. The increased velocity of the disease was the highest in the first and middle ten days of August, and the last ten days of both July and August took second place. The key period of the disease was in July and August. Clipping methods also affected the occurrence and development of the disease. Therefore, rational clipping methods at appropriate time were the available measures to decay, relieve, and control the alfalfa common leaf spot.