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四川省小麦条锈病流行区划及菌源传播路径分析 总被引:12,自引:3,他引:9
四川省是我国小麦条锈病菌Puccinia striiformis Westend f.sp.tritici Eriks的菌源地和常发区,近10年秋苗病害始见期提前、流行期加长、危害损失呈上升趋势.在实地调查基础上,利用GIS技术对全省132个小麦主产县(市、区)1987-2006年小麦条锈病发生情况进行系统分析.结果表明,四川省小麦条锈病流行区域可划分为川西北越夏区、川西南越夏及冬繁区、盆地冬繁区和川东南春季流行区.GIS软件分析发现病菌孢子在四川盆地内的传播路径为沿岷江、涪江、沱江和嘉陵江等4条河流自北向南、自西向东传播. 相似文献
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Linear models were used to investigate the effects and interactions of treatments for the control of disease in multifactorial experiments on the dynamics of the take- al disease of wheat. Analyses were based on repeated measures of disease on second successive winter wheat crops in three successive se sons. The treatments were date of sowing, presence or absence of triadimenol-containing seed treatment, autumn nitrogen and chloride applications, timing of early spring nitrogen and total spring nitrogen applications. The effects of treatments were investigated on line and quadratic trends of disease increase and on the integral amount of disease over time. Different disease variables were used to express disease relative to the total and diseased plant populations. The effects of treatments on absolute and relative numbers of diseased roots per plant were also analysed. During three se sons when disease was never severe, the effects of the treatments were shown to be variable. Late sowing consistently reduced disease during the early stages of the epidemic (in the winter months). The effect of late sowing in reducing disease, however, persisted through to the end of the growing se son in only one of the 3 years of the study. autumn nitrogen application and Baytan seed treatment (containing triadimenol) also reduced disease in some seasons. The presence of an effect for either was dependent on sowing date and was most evident on the proportion of diseased roots relative to the diseased plant rather than the total plant population. 相似文献
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Influence of spatial structure on pathogen colonization and extinction: a test using an experimental metapopulation 总被引:9,自引:0,他引:9
The Linum marginale–Melampsora lini plant–pathogen interaction has been studied extensively with regard to its epidemiology and population genetic structure (host resistance and pathogen virulence) in a natural metapopulation. In this study, this system was used in an experimental metapopulation approach to investigate explicitly how the distance (degree of isolation) between local population patches influences disease dynamics within a growing season, as well as the genetic structure of pathogen populations through stochastic colonization and extinction processes. The experimental design centred on four replicate sets of populations, within which patches were spaced at increasingly greater distances apart. Each patch consisted of an identical set of host and pathogen genotypes, with each pathogen genotype having the ability to attack only one of four host-resistance types. Over the 2 years of the experiment, the results showed clear 'boom-and-bust' epidemic patterns, with the strongest determinant of disease dynamics within a growing season being the identity of particular host–pathogen genotypic combinations. However, there were also significant effects of spatial structure, in that more isolated patches tended to exhibit lower levels of disease during epidemic peaks than patches that were close together. Extinction of pathogen genotypes from individual populations was positively related to the severity of disease during preceding epidemic peaks, but negatively related to the level of disease present at the final census prior to overwintering. The probability of recolonization of pathotypes into populations during the second growing season was most strongly related to the distance to the nearest neighbouring source population in which a given pathotype was present. Overall, these results highlight the importance of spatial scale in influencing the numerical and genetical dynamics of pathogen populations. 相似文献
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2015年度采用定容式孢子捕捉器对田间空气中小麦白粉病菌分生孢子传播的初步研究表明,在病害发生初期病菌分生孢子捕捉量比较低,但随着菌源中心病害的逐渐加重,病菌分生孢子在距菌源中心20 m和40 m远处捕捉量随之增大。线性弧度相关分析结果发现,距菌源中心北向20 m和40 m处的孢子捕捉量与风向存在显著正相关性;距菌源中心不同距离处的孢子捕捉量之间均存在极显著正相关性,且在相同方向上,距菌源中心20 m处孢子捕捉量显著高于40 m处孢子捕捉量。 相似文献
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Cheng-Fang Hong Marin T. Brewer Phillip M. Brannen Harald Scherm 《Plant pathology》2020,69(9):1721-1730
The North Georgia Mountains are the southernmost region along the United States East Coast where European wine grapes (Vitis vinifera) are grown commercially. Epidemics of downy mildew, caused by Plasmopara viticola, are frequent and severe, but little is known about the epidemiology and population biology of the pathogen in this region. Disease monitoring in an experimental vineyard from 2015 to 2017 indicated that times of disease onset and progress rates were highly variable across years and cultivars. Oospores were observed microscopically, and simulation with a process-based model indicated presence of conditions favourable for oospore germination in the spring and early summer each year. A total of 409 P. viticola isolates collected over three years were genotyped with seven microsatellite markers, revealing very high genotypic diversity, which when combined with the observation of oospores is indicative of a sexually reproducing population. Among the 409 isolates, 225 multilocus genotypes (MLGs) were identified, of which 164 were detected only once and 61 were repeated (clonal). Eight MLGs (represented by 28 isolates) were detected across years, suggesting the possibility of asexual overwintering of P. viticola in this region. Across sampling dates, the percentage of isolates belonging to nonrepeated (unique) MLGs ranged from 27.3% to 63.2%. Even towards the end of the annual epidemic, the percentage of isolates in nonrepeated MLGs was still relatively high, around 30%. These MLGs may have originated from oospores germinating late during the growing season, although incomplete sampling at earlier dates and contribution by immigration cannot be fully excluded. 相似文献
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X.‐M. Xu 《Plant pathology》2011,60(5):857-865
A simulation study was conducted to investigate epidemic development of a race‐specific pathogen in cultivar mixtures over six consecutive seasons where the spatial position of each mixture component was systematically altered between seasons. Results showed that, even for a relative large genotype unit area in a mixture, altering cultivar positions between seasons could, on average, increase disease suppression by a third over the corresponding mixture without position changes between seasons. Overall, the disease suppression achieved by mixtures with position change between seasons was close to that achieved by random mixtures. Greater redistribution distance of overwintered inoculum reduced the disease control efficacy achieved by change in the position of individual mixture components between seasons. It is therefore concluded that using mixtures with a relatively large genotype unit area together with systematic changes in the spatial positions of individual mixture components between seasons is a feasible option for integrated disease management. 相似文献
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Ednar G. Wulff Cames M. Mguni Carmen N. Mortensen Chandroo L. Keswani John Hockenhull 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(4):317-325
Biological control efficiency of an antagonistic, endophytic strain of Bacillus subtilis (strain BB) was evaluated against three strains of the black rot pathogen, Xanthomonas campestris pv. campestris (Xcc), in four Brassica crops (cabbage, cauliflower, rape and broccoli) grown during three consecutive growing seasons and on two soil types, in two different areas in Zimbabwe. Strain BB controlled the disease caused by strain Xcc B-147 in all Brassica crops during the dry and short rainy seasons. A similar effect was observed in cabbage using the strain Xcc 33908. Biological control was effective in broccoli, but not in cabbage and rape during the main rainy season in clay loam soil and limited biological control effect was still observed when these crops were grown in sandy loam soil. The endophytic colonisation of cabbage roots by strain BB was confirmed by immuno-blotting during the whole growing season. Biological control of black rot with strain BB is discussed in relation to its effect on Xcc strains, Brassica crops and to the effect of weather and soil conditions. 相似文献
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沈阳地区葡萄霜霉病流行时间动态及其气象影响因子分析 总被引:1,自引:0,他引:1
通过2012-2014年田间小区试验,对沈阳地区葡萄霜霉病自然发病情况进行了系统调查和对比分析,并对影响葡萄霜霉病流行动态的气象因素进行了相关性分析。结果表明,沈阳地区葡萄霜霉病的季节流行曲线是典型的单峰S形曲线。应用SPSS19.0软件分析,明确了Logistic模型能够反映沈阳地区葡萄霜霉病流行时间动态情况。同时,推导了病害流行阶段:指数增长期为7月上旬至7月下旬,该时期为最佳药剂防治时期;逻辑斯蒂增长期为7月下旬至8月下旬;衰退期为8月下旬至葡萄生育末期。不同生长季病害发生日期、流行阶段天数和最大病情指数虽各不相同,但与Logistic模型推导趋势基本一致。各个流行阶段病害的表观侵染速率表现为:始发期>盛发期>衰退期。始发期和盛发期的是决定整个生长季葡萄霜霉病流行程度的关键时期。气象因素对葡萄霜霉病的流行有明显影响,其中表观侵染速率与7 d平均相对湿度、7 d累计降雨量和7 d叶面湿润时数成显著正相关,而与7 d平均气温呈显著负相关,以上4个气象因素是影响沈阳地区葡萄霜霉病流行的主导因子。 相似文献
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ABSTRACT It is generally agreed that ascospores are the origin of primary infections for the disease septoria tritici blotch of wheat caused by the fungus Mycosphaerella graminicola (anamorph Septoria tritici). The epidemic during the growing season was previously ascribed to the asexual pycni-diospores dispersed over short distances by rain splash, but recent observations suggest that the airborne ascospores also may play a role. As a consequence, the composition of the pathogen population over the growing season may change through genetic recombination. In an attempt to resolve the relative importance of the two spore types to the epidemic over the growing season, a model simulating disease caused by both types of spores was constructed and analyzed. The conclusion from the analysis of this model is that sexual recombination will affect the genetic composition of the population during a growing season. A considerable proportion of spores released at the end of the growing season may be sexual descendants of the initial population. However, ascospores are unlikely to affect the severity of the epidemic during the growing season. This is due to the much longer latent period for pseudothecia compared with pycnidia, resulting in ascospores being produced too late to influence the epidemic. 相似文献
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生姜根结线虫病原鉴定及发生规律 总被引:5,自引:1,他引:5
采用田间调查、接种试验、电镜与显微镜观察以及酯酶同工酶电泳等方法,对引发生姜癞皮病的病原及发生规律进行了研究.结果表明,引起生姜癞皮病的病原为南方根结线虫Meloidogyne incognita.该病在每年6月中旬开始发生,8、9月份危害严重.病原在生姜上一年可发生完整的4代,完成1代平均约需35天.病原主要在0~40cm的土层内分布和危害,但具体分布情况依寄主生长状况而稍有差异.南方根结线虫繁殖速率受初始接种密度的影响也很大,当初始接种密度较低时,线虫繁殖速率较高,初始接种密度增大,繁殖速率降低,其平衡密度为每100g干土746.20个卵. 相似文献
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Stéphane Pietravalle Stéphane Lemarié Frank van den Bosch 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):107-116
A seasonal model, where a growing season is defined as the time between sowing and harvest and alternates with an inter-crop
period, was derived to study the effects of the ‘cost of virulence’ and cropping ratio on durability of resistance. We assumed
a single strain of virulent pathogen, a single strain of avirulent pathogen and two cultivars (one resistant and one susceptible)
and studied two measures of durability of resistance (‘take-over time’ and ‘usefulness time’). Take-over time is defined as
the time needed for the virulent strain of the pathogen to reach a preset threshold and predominate over the previous pathogen
population. Usefulness time is the time needed before the estimated gain in green canopy area duration per plant through the
use of the resistant cultivar becomes negligible. The model suggested that, although it could take several seasons before
the virulent strain of the pathogen predominated over the previous pathogen population, the usefulness time of the resistant
cultivar was always much shorter. Furthermore, increasing selection for the virulent strain of the pathogen (through increasing
the cropping ratio of the resistant cultivar) caused the virulent strain of the pathogen to invade the system more rapidly.
Cost of virulence, reflecting differences in pathogen infection rates between the four possible combinations of cultivar/pathogen
strain, significantly affected durability of resistance, with the dynamics of the virulent and avirulent strains ranging from
a case where the virulent strain of the pathogen died out to a case where the virulent strain of the pathogen invaded the
resident pathogen population. An intermediate state, where the system reached equilibrium and the virulent strain of the pathogen
neither became predominant nor died out, was defined as ‘coexistence’ of both strains of the pathogen. Occurrence of coexistence
was directly related to the cost of virulence since it did not occur when virulence of the pathogen did not have a fitness
cost. Two methods to include cost of virulence in the model gave similar results in relation to the two measures of durability
of resistance studied. 相似文献
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Variation in aggressiveness and its consequences for disease epidemiology were studied in the Cakile maritima–Alternaria brassicicola host–pathogen association. Variability in pathogen growth rates and spore production in vitro , as well as disease severity and lesion growth rate on C. maritima in glasshouse inoculation trials, were investigated . Substantial variation was found in growth rates among individual A. brassicicola isolates, as well as among pathogen populations. A significant trade-off also existed between growth and spore production, such that faster-growing isolates produced fewer spores per unit area. While there was little evidence for a link between growth in vitro and either disease severity or lesion development among fast- vs slow-growth isolate classes at the individual isolate level, the results suggest that variation in pathogen fitness components associated with aggressiveness may influence disease dynamics in nature. An analysis using an independent data set of disease prevalence in the associated host populations found a significant positive relationship between the average growth rate of pathogen populations in vitro and disease progress over the growing season in wild host populations. Trade-offs such as those demonstrated between growth rate and spore production may contribute to the maintenance of variation in quantitatively based host–pathogen interactions. 相似文献
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北京地区花生病毒病及流行规律研究 总被引:3,自引:1,他引:3
1985—1987年研究表明北京地区花生上流行的病害主要有黄瓜花叶病毒CA株系(CMV-CA)引起的黄花叶病害和花生轻斑驳病毒(PMMV)引起的轻斑驳病害。血清鉴定451份花生病害样品,黄花叶病害样品受CMV-CA侵染占95.7%,轻斑驳病害样品受PMMV侵染占91.3%,中后期病害样品受CMV-CA和PMMV复合感染较普遍。CMV种传率2%左右,种传病苗在花生出苗后开始出现,6月病害进入高峰。三年CMV-CA流行程度明显不同,主要取决于苗期蚜虫发生早晚、发生量及苗期降雨量。PMMV种传率低于1%,病苗出现稍晚,但病害扩散快,6月上旬进入高峰,7月上、中旬发病率达100%。三年流行程度差异不明显。 相似文献
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Julie M. Steed Andreas Baierl Bruce D. L. Fitt 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(4):359-373
In winter oilseed rape experiments at Rothamsted in 2000/01 to 2002/03 growing seasons, the severity of phoma stem canker
epidemics in summer depended on the timing of phoma leaf spot epidemics in the previous autumn, and hence on the timing of
Leptosphaeria maculans ascospore release. The first major release of L. maculans ascospores was earlier in 2000 (26 September) and 2001 (18 September) than in 2002 (21 October). Consequently, the autumn
phoma leaf spot epidemic was also earlier in 2000 and 2001 than in 2002. The resulting stem canker epidemics were severe by
harvest (July) in 2001 and 2002 but not in 2003. No correlation was found between the severity or duration of phoma leaf spotting
(lesion days or lesion °C-days) and the subsequent severity of phoma stem canker epidemics. Rates of leaf production and loss
were similar in the three growing seasons. Out of ca. 25 leaves produced on plants during each season, leaf numbers 10–14 generally remained on plants for the longest. Treatment
with flusilazole + carbendazim in autumn decreased the severity of phoma leaf spotting for several weeks after treatment,
decreased the severity of stem canker the following summer and increased yield significantly in 2001 and 2002 but not in 2003.
The most effective timings for flusilazole + carbendazim application were when leaves 7–11 were present on most plants and
at least 10% of plants were affected by phoma leaf spot. Two half-dose applications of fungicide reduced phoma stem canker
and increased yield more than a single full dose application when phoma leaf spot epidemics were early (<800 °C-days after
sowing). 相似文献