枣锈病越冬夏孢子萌发及侵染的研究简报

枣锈病(Phakopsora ziziphi-vulgaris(P. Henn)Diet.)为枣树的3大病害之一,是枣区的重要流行性病害,近10年河北省5次流行。发病时叶片背面布满了深黄色夏孢子堆,引起早期落叶,导致大枣和金丝小枣大幅度减产,品质下降,影响外贸内销降低枣农收入。此病的侵染循环特别是转主寄主及初侵染来源均不很清楚,因而影响枣锈病的防治效果。我们从1990年开始在防治同时探索枣锈病的初侵染来源及其在侵染上的作用。

环境因子对杨梅凋萎病菌分生孢子萌发及侵染的影响

【目的】开发有效的预测预报和防控技术,以控制凋萎病对杨梅的危害。【方法】研究不同温度、相对湿度及营养溶液对凋萎病菌2个菌株的分生孢子培养2、4、6、12和24 h后萌发的影响,以及不同温度和相对湿度对2个凋萎病菌菌株分生孢子侵染杨梅后5、7、9、11、13和15 d后的影响。【结果】温度和相对湿度对凋萎病菌2个菌株的分生孢子萌发和侵染都有着显著性的影响。20~30℃和25~35℃分别最适合分生孢子萌发和侵染,相对湿度等于或者高于60%时分生孢子培养48 h萌发率接近或者超过50%,最适合侵染的相对湿度是60%~80%。2个菌株的分生孢子在水里都能萌发,但是萌发率较低,0.1%(w)浓度的葡萄糖、马铃薯煎汁、蔗糖、硝酸钾、磷酸二氢钾内分生孢子都能较好地萌发。【结论】杨梅凋萎病菌能够在大范围的温度和相对湿度条件下完成萌发和侵染,并且分生孢子可以利用多种营养萌发。

避雨栽培对葡萄霜霉病发生的影响与葡萄冠层微气象因子的关系

系统比较了云南省石林县(‘红地球’)和弥勒县(‘水晶葡萄’)葡萄园采用避雨栽培和露天栽培对葡萄霜霉病Plasmoparaviticola(Berk.&Curtis)Berl.&de Toni.的防治效果,监测了田间葡萄园内避雨栽培和露天栽培处理中葡萄霜霉病的发生流行与植株冠层气象因子的变化情况,并结合适宜葡萄霜霉病病害循环的温度、相对湿度、叶面持露时间及田间葡萄植株冠层微气象因子的变化对避雨栽培有效防治葡萄霜霉病的气象原理进行了分析。结果表明,避雨处理可有效控制葡萄霜霉病的发生和危害,石林县和弥勒县两地葡萄园的防治效果分别达到97.84%和66.29%。弥勒县‘水晶葡萄’对霜霉病的抗性较强,霜霉病发生较轻,但在避雨栽培条件下霜霉病的病情指数也显著低于对照。植株冠层微气象因子变化分析表明,避雨栽培可以减少决定霜霉病菌能否成功侵染的叶面水膜持续时间,创造不适宜霜霉病菌萌发和侵入的条件,还可以显著减低棚内植株冠层适宜孢子囊产生的相对湿度的持续时间,减少霜霉病菌的侵染菌量,从而有效地控制了霜霉病的发生和危害。

苹果褐斑病在山东半岛中部的周年流行动态

【目的】褐斑病是中国苹果叶部的重要病害,主要导致苹果树早期大量落叶。研究旨在明确褐斑病的周年发生动态,确定病害的关键防治时期,为病害的流行预测和防控提供参考。【方法】2009和2010年3—7月份,每隔15 d自山东莱阳和青岛两地的苹果园内定期采集落地病叶,随机挑取病叶正面的子实体,镜检已形成拟分生孢子和子囊孢子的子实体,依据拟分生孢子盘和子囊盘在子实体中所占百分率,分析越冬病菌的发育动态。2008—2010年6—10月份,在山东莱阳和青岛的果园内,每隔15 d定树定枝系统调查同一批枝条上所有叶片的发病率和落叶率,将系统调查数据拟合逻辑斯蒂模型,获得能描述褐斑病发病动态的模型参数。2010和2012年9—11月份,每隔10 d从苹果树上随机摘取具有典型症状的苹果褐斑病叶,切取分生孢子盘,镜检分生孢子盘上小型孢子和分生孢子各占的比率,根据小型孢子在分生孢子盘上所占的相对比率的变化,分析褐斑病菌的发育动态。【结果】苹果褐斑病菌在越冬病叶上能产生拟分生孢子和子囊孢子两种类型的孢子。拟分生孢子于3月初至6月底形成,高峰期出现在5月中旬。自苹果树萌芽期开始,拟分生孢子就可以随雨水溅散传播,侵染树体下部叶片。拟分生孢子侵染的叶片,大部分于6月底之前脱落,对褐斑病后期流行作用不大。子囊孢子于5月中旬至6月底成熟,可以随气流传播侵染树体上部叶片,是导致苹果褐斑病后期流行的主要初侵染菌源。子囊孢子侵染的叶片自7月上中旬开始发病,初侵染形成的病叶率低于2%。7月份,初侵染病斑大量产孢,并进行再侵染,病原菌不断积累,7月底病叶率可增长至5%左右。8月份,初侵染病斑和再侵染病斑大量发病,并产孢侵染,导致病叶率迅速增加。8月下旬褐斑病发病达高峰期,12 d后形成落叶高峰。6—9月份苹果褐斑病的累积病叶率和累积落叶率随时间的变化动态可用逻辑斯蒂模型描述。进入9月份,褐斑病菌开始产生小型孢子(性孢子),小型孢子在分生孢子盘上所占比率呈直线增长。10月份褐斑病菌逐渐停止产生分生孢子,进入越冬预备期。【结论】苹果褐斑病在山东半岛中部的周年流行动态可划分为4个阶段:自苹果萌芽至6月底为褐斑病菌的初侵染期。其中5月下旬到6月底是子囊孢子的初侵染期,也是全年防治褐斑病的第1个关键时期。7月份为褐斑病的指数增长期,也是全年防治褐斑病的第2个关键时期。8—9月份是褐斑病的逻辑斯蒂增长期,也是褐斑病的盛发期。10月份褐斑病菌进入越冬预备期。

Infection of the Anther-smut Microbotryum violaceum in Populations of Silene dioica: Variation in Floral Morphology, Patterns of Spore Deposition and Pathogen-Pollinator Mediated Selection

The anther-smut Microbotryum violaceum ( Brandenburger and Schvinn) G. Deml. and Oberw.) causes a systematic infection of its host Silene dioica ( L.) Clairv., resulting in sterility and production of teliospores (dispersal propagules) in flowers. These spores are transmitted to healthy plants mainly by flower visitors. The behavioral responses of flower visitors to a variation in floral characters are not only likely to affect rates of pollen export/import, but also the rate of spore deposition and probability of disease. In a transplantation experiment, using plants from four different populations, we tested for correlation between variation in female floral morphology and patterns of spore and pollen deposition, and a resulting risk of disease. The source populations in this experiment were located on four islands in Skeppsvik archipelago in northern Sweden, and represented a gradient of disease incidence from completely healthy ( Island 1), low incidence ( Island 2) to high incidences ( Islands 3 and 4) of disease. Fifty plants from each population were transplanted to the center, of the population on Island 4. There were significant differences among the transplants in floral characters, i.e. corolla size, style length and ovule number. Plants from the non-diseased population had larger flowers and longer styles than plants from the highly diseased populations. Numbers of pollen grains and spores deposited on flowers were strongly and positively correlated. We found that plants originating from the non-diseased population captured approximately 4 times more pollen and 9 times more spores, per flower than die individuals from the resident population (Island 4, population 4). The incidences of disease among plants, from the four populations differed significantly, and was 37%, 20%, 18% and 0 for populations 1, 2, 3 and 4 respectively. In a survey of ten populations we found a significant negative correlation between the mean style length ( positively correlated with corolla size and ovule number) among healthy plants and incidence of disease in these populations. The potentiality for pathogen-pollinator mediated selection oil floral characters; and consequences for gone flow between populations of Silene dioica are discussed.