Abstract

Surveys of alfalfa (Medicago sativa L.) seed production fields on the Canadian Prairies from 1993 to 2017 demonstrated that epidemics of blossom blight caused by Botrytis cinerea Pers. and Sclerotinia sclerotiorum (Lib.) de Bary developed almost every year at some location(s). Blossom blight symptoms were prominent when epidemics were severe, but more difficult to identify when present at low levels, which likely contributes to the infrequent reporting of blossom blight in alfalfa seed production. Epidemics were observed across the entire region, from the Peace River region of northern Alberta to southern Manitoba, consistently associated with relatively cool, wet weather conditions. The widespread nature of blossom blight on alfalfa in the years following its initial diagnosis in Canada in 1993, together with the ubiquitous distribution of the pathogens involved on other crops, indicated that blossom blight was almost certainly present on alfalfa seed crops on the Canadian Prairies for many years before the initial identification. It appears likely that blossom blight continues to cause yield loss at some locations in most years.

摘要

1993 年至 2017 年对加拿大大草原上的苜蓿 ( Medicago sativa L.) 种子生产田的调查表明，灰霉病 (Botrytis cinerea Pers)引起的花枯病流行。和核盘菌(Lib.) de Bary 几乎每年都在某些地方开发。当流行病严重时，花枯病症状很突出，但在低水平存在时更难识别，这可能导致在苜蓿种子生产中很少报告花枯病。从阿尔伯塔省北部的皮斯河地区到马尼托巴省的南部，整个地区都出现了流行病，一直与相对凉爽潮湿的天气条件有关。1993 年在加拿大初步诊断出苜蓿花枯病后的几年里，该病的普遍性质，以及其他作物上普遍存在的病原体，表明花枯病几乎肯定存在于加拿大大草原的苜蓿种子作物上在最初的鉴定之前很多年。