摘要
【目的】腐烂病是苹果树的重要枝干病害,主要造成死枝、死树。论文旨在明确低温等环境因子和枝条龄期等寄主因子对腐烂病菌(Valsa mali)侵染致病的影响,分析腐烂病流行成灾的原因,为腐烂病的流行预测和防控提供依据。【方法】通过人工控制环境条件下的接种试验,检测腐烂病菌在苹果枝干各部位的定殖率,观测腐烂病菌在伤口内的定殖部位,测试低温冷冻、枝条浸水后冰冻、枝条失水、枝条龄期等因子对接种腐烂病菌侵染致病的影响。【结果】8月份用分生孢子喷雾接种的苹果树,次年3月份检测,7个枝位的带菌率都接近或超过90%;接种到伤口上的腐烂病菌主要定殖于伤口坏死组织内,并在死组织内生长扩展,但没有穿透伤口外围的愈伤木栓层而侵入活体的皮层组织致病;在检测的6个枝位中,新鲜伤口对腐烂病菌侵染致病最为敏感,接种发病率最高,果柄痕次之,叉丫、芽眼和果苔枝的敏感性稍差,发病率稍低,皮孔抗病性最强,接种病菌不能致病;低温冷冻和浸水后冰冻(枝条上形成冰晶)都能增加枝条芽眼部位对接种腐烂病菌的感病性,其中-25和-18℃两个温度下处理枝条的接种发病率显著高于-10、-7和0℃3个温度处理枝条的接种发病率,浸水后冰冻枝条(模拟冬季降水后结冰的枝条)的接种发病率显著高于相同温度处理未结冰枝条的发病率;在低温冷冻和浸水后冰冻处理的枝条中,一年生枝条的接种发病率显著高于二年生枝条的发病率;一年生枝条经浸水冰冻处理后,梢部的接种发病率显著高于同一枝条基部的发病率;浸水后冰冻再经失水处理枝条(模拟枝条越冬后因大风、高温等失水),对腐烂病菌的侵染致病更加敏感,接种发病率显著高于浸水后冰冻枝条的发病率,而且失水量越大,接种发病率越高,芽眼部位的接种发病率最高可达85%。【结论】腐烂病菌易在苹果枝干上定殖,定殖病菌主要在伤口或枝干表层死组织内存活并生长,定殖病菌能否侵染致病关键取决于环境因子对枝条栓皮层的破坏;低温冷冻,尤其低于-15℃的低温冻害能破坏枝条的栓皮层和皮层,增加苹果枝条对腐烂病菌侵染致病的敏感性;与低温冷冻相比,浸水后冰冻对枝条栓皮层的破坏作用更大,结冰枝条对腐烂病更加敏感;枝条浸水冰冻后再失水,对枝条的破坏作用尤为严重,枝条越冬后失水能显著增加其对腐烂病菌侵染致病的敏感性;枝条的龄期不同,栓皮层的发育成熟度、强度和韧度各不相同,受不良环境因子的影响后,其受到破坏的程度也不同;树体不同部位栓皮层的结构不同,对腐烂病菌侵染致病的敏感性也存在明显差异。
【Objective】Valsa canker,mainly causing dead branches and dead trees,is an important branch disease of apple trees.The objective of this study is to clarify the impact of environmental factors such as low temperature and host factors such as the age of branches on the infection and occurrence of valsa canker,to analyze the causes of the disease epidemics,and to provide a basis for the prediction and control of the disease.【Method】Inoculation experiments were conducted under artificial controlled environmental conditions.The conidia colonized ratios of Valsa mali on different parts of apple branches were detected,the colonization sites of the pathogen in wounds were examined,and effects of the factors such as freezing,ice forming on branches,loss of water of branches,and age of branches on the infection of the pathogen and occurrence of the disease were tested in the experiments.【Result】The colonized percentages of V.mali,i.e.the site carried the pathogen,on the 7 different branch sites of the apple trees inoculated with conidial suspension in the August were close to or more than 90%when examined in March of the following year.The pathogen inoculated on the wounds mainly colonized,grew and expanded in the necrotic tissue of the wounds,but did not penetrate the cork layer around the wound and invade the living cortical tissue to cause canker disease.Among the 6 examined branch sites,fresh wounds were the most susceptible to infection of V.mali,with the highest disease incidence of inoculated sites,followed by fruit stalk scars.The forks,bud eyes and fruit moss were less susceptible and disease incidences of inoculated sides were slightly lower.The lenticels were resistant to pathogen infection and no inoculated sites developed to canker.Both freezing and freezing after soaking(form ice on branch surface)can increase the susceptibility of branches to infection of V.mail.In the tested branches,the disease incidence of inoculated sites on the branches treated at-25 and-18℃were significantly higher than that treated at-10,-7 and 0℃,and the incidence on branches frozen after soaking(simulating branch freezing after precipitation in winter)was significantly higher than that of uniced branches treated at the same temperature.Among the branches that were frozen and frozen after soaking,the disease incidence of inoculated sites on 1-year-old branches was significantly higher than that of 2-year-old branches.The disease incidence of inoculated sites at the tips of 1-year-old branches was significantly higher than that at the base of the same branches when frozen after soaking.The branches subjected to water loss after frozen(simulating the branches that lose water due to wind and high temperature after overwintering)were more susceptible to the infected V.mali,and the disease incidence of inoculated sites was significantly higher than that on frozen branches after soaking.The greater the amount of water losing,the higher the disease incidence,and the highest disease incidence of inoculated bud eye can reach 85%.【Conclusion】V.mali is easy to colonize on apple branches,and colonized pathogens mainly survive and grow in dead tissues in wounds or on the surface of branches.Whether colonized pathogens can infect and cause disease mainly depends on environmental factors destroying the cork layer of the branches.Freezing,especially freezing damage at the temperature below-15℃can destroy the cortex and cork layer of the branches,and increase the susceptibility of apple branches to infection of V.mali.Compared with freezing,freezing that form ice crystals on the surface of branches lead to a greater damage to the cork layer of branches,and the branches are more susceptible to the infection of the pathogen.The damage of water loss after freezing to the branches is particularly serious.The loss of water after the branches overwinter can significantly increase susceptibility of the branches to infection of the pathogen.The age of the branches is different,the developmental maturity,strength and toughness of the cork layer are different,and the degree of damage to the cork layer is also different when the branches were affected by adverse environmental factors.The structure of cortex in different sites of the tree is different,and there are obvious differences in the susceptibility to the pathogen infection.
作者
林晓
孙传茹
王彩霞
练森
董向丽
李保华
LIN Xiao;SUN ChuanRu;WANG CaiXia;LIAN Sen;DONG XiangLi;LI BaoHua(College of Plant Health and Medicine,Qingdao Agricultural University/Key Lab of Integrated Crop Pest Management of Shandong,Qingdao 266109,Shandong)
出处
《中国农业科学》
CAS
CSCD
北大核心
2021年第11期2333-2342,共10页
Scientia Agricultura Sinica
基金
国家自然科学基金(31371883)
国家重点研发计划(2016YFD0201122)
国家苹果产业技术体系(CARS-28,CARS-27)。
关键词
苹果树腐烂病
皮层结构
腐烂病菌
病菌定殖
病菌侵染
冷冻
结冰
失水
valsa canker of apple tree
cortex structure
Valsa mali
pathogen colonization
pathogen infection
freezing
ice forming
water lose