Epidemiology of sclerotinia stem rot of rapeseed in Saskatchewan
Epidemiology of sclerotinia stem rot of rapeseed in Saskatchewan
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DOI：
10.1080/07060668209501319
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发表时间：
1982-06
期刊：
影响因子：
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通讯作者：
R. Morrall;J. Dueck
中科院分区：
文献类型：
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作者：
R. Morrall;J. Dueck
材料和方法这项研究是在萨斯喀彻温省中东部的梅尔福特地区，一个传统的油菜种植面积与严重的菌核病的历史。1977年研究了25个平均面积为40公顷的田地，1978年研究了29个平均面积为60公顷的田地。这些在5月或6月初选择，此时植物仍处于幼苗或莲座阶段，并且没有疾病。尽可能从农民那里获得以下农艺数据：品种、种子来源和处理、播种日期和播种率、施肥剂和除草剂施用、过去12个月的栽培实践、过去4年田间作物历史、相邻田间作物历史。在秋季，对所有研究田的作物进行包裹（切割并放置在料堆中）和合并的日期以及农民对产量的估计进行了汇编。从6月上旬或中旬到8月下旬或9月上旬，即在作物被包裹之前不久，每隔一周左右访问一块田地，以监测（a）S.（B）茎腐病的侵染率;（c）植物酚类物质。对于前两个目的，每次都使用野外相同的四个相距甚远的区域作为破坏性采样点。在每个地点的每个日期，记录一个人搜索5 min所发现的Apotherapy或Apotherapy簇的数量。这些数字后来被简化为对每个油田中的apotherapy总丰度的粗略估计。在田间首次发现病害后，通常在每个采样点，在每个日期对200株植物的感染进行评分。分别对茎基部病变（感染部分和土壤表面之间没有健康组织）和气生病变（茎感染部分下方的健康组织）进行计数。最初认为，茎基部病变可能是由于一个独特的接种源，即位于非常接近油菜籽茎的土壤中的菌核，并能够通过表面菌丝萌发引起感染。在每次访问时，根据生长阶段关键词（7）评估每个田地中植物发育的近似平均阶段。1977年，使用离每个田地最近的加拿大环境部气象站的日降雨量数据。这些监测站距离农田最多40公里。1978年，在定期监测期间，雨量计被放置在研究领域。通过将雨量计记录与加拿大环境部站点的每日数据进行比较，并直接使用加拿大环境部在生长季节早期和晚期的数据，为每个字段编制了整个生长季节的每周降雨总量。
Materials and methodsThe study was done in the Melfort region of east-central Saskatchewan, a traditional area of rapeseed cultivation with a history of severe sclerotiniastem rot. Twenty-five fields with a mean size of 40 ha were studied in 1977 and 29 with a mean size of 60 ha were studied in 1978. These were selected in May or early June when the plants were still in the seedling or rosette stages and disease was absent. Whenever possible, the following agronomic data were obtained from the farmers: cultivar, seed origin and treatment, seeding date and rate, fertil izer and herbicide applications, cultural practices in the previous 12 months, crop history of the field for the previous 4 years, crop history of adjacent fields. In autumn the dates on which the crops had been swathed (cut and placed in windrows) and com bined, and the farmers' estimates of yield were compiled for all study fields. From early or mid June until late August or early September, ie shortly before the crop was swathed, each field was visited at about weekly intervals to monitor (a) the frequency of apothecia of S. sclerotiorum on the soil surface,(b) the inci dence of stem rot infection, and (c) plant phenol ogy. For the first two purposes the same four widely separated areas in the field were utilized each time as destructive sampling sites. At each site on each date the numbers of apothecia or clusters of apothecia found by one person searching for 5 min were recorded. These figures were later reduced to crude estimates of overall abundance of apothecia in each field. After disease was first noticed in a field, groups of 200 plants were scored for infection on each date, normally at each sampling site. Separate counts were made of basal stem lesions (no healthy tissue between the infected portion and the soil surface) and aerial lesions (healthy tissue below the infected portion of the stem). It was initially believed that basal stem lesions might result from a distinctive inoculum source, namely sclerotia in the soil situated very close to rapeseed stems and capable of causing infection through superficial myceliogenic germination. The approx imate mean stage of plant development in each field was assessed according to a growth stage key (7) at each visit.In 1977 daily rainfall data were used from the nearest Environment Canada meteorological sta tion to each field. The stations were up to 40 km from the fields. In 1978 rain gauges were placed in the study fields during the period of regular moni toring. Approximate weekly rainfall totals for the entire growing season were compiled for each field by interpolation from the rain gauge records in comparison with daily figures from Environment Canada stations, and by direct use of the Environ ment Canada data for the early and late parts of the growing season.