Laboratory evaluation methods of apple Valsa canker disease caused by Valsa ceratosperma sensu Kobayashi.
Laboratory evaluation methods of apple Valsa canker disease caused by Valsa ceratosperma sensu Kobayashi.
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发表时间：
2010
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通讯作者：
JieLing Wei;H. Lili;ZuoPeng Gao;X. Ke;Zhen-sheng Kang
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作者：
JieLing Wei;H. Lili;ZuoPeng Gao;X. Ke;Zhen-sheng Kang
苹果树腐烂病是我国苹果树上危害最大的树皮腐烂病之一。本研究的目的是建立一种简单、稳定、高效、简便的实验室病害评价方法。用致病菌03-8对富士苹果树的离体叶片、嫩枝、果实和枝条进行不同程度的伤口处理。将样品在25℃下保存在饱和湿度箱中。在未接种和/或未受伤的样品中没有发现疾病，而在伤口接种的处理中发生病变。创面类型对病情发展影响较大。伤叶上侧病变发展速度明显快于伤叶下侧。叶片上侧面针刺1次与10次的伤口愈合率无显著性差异。刺伤在新梢上形成的病斑比叶痕大。刺果1次、10次、去部分果皮3种处理间差异显著（P0.05）。此外，病害在叶、嫩梢和果实样品上的发展（1.5-2天）比在枝条上（10天）快得多。用4个不同毒力的菌株对该方法进行了可靠性和稳定性检验。结果表明，不同菌株引起的病害在发病后3 d内表现明显不同，因此，膨大的叶片或嫩梢比枝条和果实更适合作为病斑的材料。因此，建议在生长季节以离体展开叶或嫩梢为材料，针刺1次后，在叶片上部或嫩梢表面贴上病原菌盘，在25℃的湿度箱中放置2 d，然后测量病斑直径。该方法可在短时间内对材料进行定量评价，在重复试验、抗病品种筛选、室内毒力测定和药效测定等方面取得较好效果。
Valsa canker is one of the most destructive bark-rot diseases on trunk of apple tree in China. The aim of the research was to develop a simple but stable, efficient and easy method for disease evaluation in laboratory. Excised leaves, young shoots, fruits and twigs of ‘Fuji’ apple trees were inoculated with a virulent isolate 03-8 after making different wounds. The samples were kept at 25℃ in a saturated moisture box. No disease was found in uninoculated and/or unwounded samples, while lesions were occurred in treatments by wound inoculation. The type of wound affected the disease development greatly. Lesions developed much faster on upper side wound than lower side of the leave. No significant difference was observed between wounds pricking one time and ten times on upper side of the leave. Bigger lesions were formed on young shoots by pricking wound than leaf scar. There were significant differences (P0.05) among wounds of pricking one time, ten times and removing partial peel on fruits. Also, the disease developed much faster on leaf, young shoot and fruit samples (1.5-2 days) than on the twigs (10 days). Furthermore, four different virulent isolates were used to test the reliability and stability of the method. The results showed that expanded leaves or young shoots were better materials than twigs and fruits because different lesions caused by the different isolates could be observed obviously in less than 3 days. Thus, the evaluation method for Valsa canker was suggested as follows: using detached expanded leave or young shoot as plant material in growing season, inoculating one pathogenic fungi disc on the upper side of leaf or surface of shoot after pricking one time with needle, keeping at 25℃ for 2 days in a satisfied moisture box, then measuring the lesion diameter. This me-thod could be used to assess materials in quantity at a short time, obtain good results from replication, screen resistant cultivar, test isolate virulence and chemical efficacy indoor.