tailieunhanh - Báo cáo khoa học: "Frequency and evolution of Melampsora larici-populina Klebahn"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:"Frequency and evolution of Melampsora larici-populina Klebahn. | Ann Sá For 1992 49 1-15 Elsevier INRA 1 Original article Frequency and evolution of Melampsora larici-populina Klebahn races in north-western France J Pinon INRA Laboratoire de Pathologie Forestidre Centre de Recherches de Nancy 54280 Champenoux France Received 11 February 1991 accepted 7 September 1991 Summary Race populations in M larici-populina were studied for 4 years nearly 7 000 identifications . Race E1 is ubiquitous in France and probably in western Europe E2 exists at least in the northern half of France in Belgium and in the Netherlands and E3 is present in the east of France and very probably in the west and south-west as well. Races E2 and E3 occurred irregularly among years on larch the alternate host. There was some link between race populations on larch and on poplar when E2 and E3 were infrequent on poplar at the end of the growing season they were practically undetectable on larch the following spring. On universal poplar clones clones susceptible to all known races E2 and E3 were in the minority but their counterselection was not evident. On differential clones susceptible only to E2 or E3 the compatible race was in the majority but at the end of the growing season infections by incompatible races that do not infect poplar growing actively in the greenhouse were detected. This phenomenon is discussed and several hypotheses are proposed. Specific resistance delays the epidemics in differential clones. Up to now no race combining all the virulences has been found which is in agreement with the low theoretical frequency of such a race. E2 and E3 seem to remain stable and it is suggested that race populations reflect host populations. races population Melampsora larlcl-popullna I Populus I resistance Résumé Fréquence et évolution des populations de races de Melampsora larici-popullna Klebahn dans le Nord-Est de la France. Les populations raciales de M larici-popullna ont été étu-diées pendant 4 ans près de 7 000 identifications dans plusìeurs .