Panjehkeh N, Yosefi A
Department of Plant Protection, Faculty of Agriculture, University of Zabol, Iran.
Commun Agric Appl Biol Sci. 2011;76(4):635-41.
Shot hole disease of stone fruit trees caused by some plant pathogenic fungi is a major constraint to stone fruit production worldwide where the trees are grown. Identification of the causal agents of the disease and their overwintering forms in stone fruit trees of Khorasan Razavi was necessary for disease management programs. Buds, twigs, fallen leaves and fruits were collected from the infected peach, apricot, nectarine and almond trees in winter 2007. The samples were superficially disinfested in 1% sodium hypochlorite for 2-3 min and then in 70% ethanol for 45 sec. Two to three fragments of 4x4 mm from each tissue were separately cultured on 2% water agar and potato dextrose agar (PDA), and purified on PDA. Just a pathogenic fungal species, Wilsonomyces corpophilus was isolated from the infected buds and twigs. No microorganism was isolated from the fallen leaves and fruits collected from underneath of the infested stone fruit trees. Pathogenicity of the fungus was examined on detached shoots of current year of four varieties of stone fruit trees. Fungal discs were placed under the bark of the bud base. Control shoots were similarly treated with sterile PDA discs. Inoculated shoots were placed in a humid growth chamber at 25 degrees C. Fungal hyphae appeared at 30 days post inoculation. Control shoots were asymptomatic. Pathogenicity intensities or lesion lengths were significantly different among the four varieties tested. A completely randomised design with five replicates was employed to measure the number of spores in infested buds and twigs of each variety of stone fruit tree. The samples were sliced and placed into a glass tube of centrifuge containing 3 ml of sterile distilled water. They were mixed on a vortex mixer for 30-40 min and centrifuged at 3000 rpm for 5 min. Pelleted material from each sample was suspended in 500 microl of sterile distilled water and the spores were counted using a hemocytometre. Results revealed that the fungus overwinters as hyphae and conidia in the infected buds, and as hyphae and globular chlamydospores in twig lesions.
由某些植物病原真菌引起的核果类果树穿孔病是全球种植核果类果树地区核果生产的主要限制因素。确定呼罗珊拉扎维省核果类果树该病的病原及其越冬形式对于病害管理计划很有必要。2007年冬季，从受感染的桃树、杏树、油桃树和扁桃树上采集了芽、嫩枝、落叶和果实。样本先在1%次氯酸钠中进行表面消毒2 - 3分钟，然后在70%乙醇中消毒45秒。从每个组织切下2 - 3片4×4毫米的碎片，分别接种在2%水琼脂和马铃薯葡萄糖琼脂（PDA）上，并在PDA上纯化。仅从受感染的芽和嫩枝中分离出一种病原真菌，嗜果刀孢菌。从受侵染核果类果树下方收集的落叶和果实中未分离到微生物。在四种核果类果树当年生离体嫩枝上检测了该真菌的致病性。将真菌菌碟置于芽基部的树皮下方。对照嫩枝用无菌PDA菌碟进行类似处理。接种后的嫩枝置于25℃的潮湿生长室中。接种后30天出现真菌菌丝。对照嫩枝无症状。在所测试的四个品种中，致病性强度或病斑长度存在显著差异。采用完全随机设计，重复五次，以测量每个核果类果树品种受侵染芽和嫩枝中的孢子数量。将样本切片后放入装有3毫升无菌蒸馏水的离心玻璃管中。在涡旋混合器上混合30 - 40分钟，然后以3000转/分钟离心5分钟。每个样本的沉淀物质悬浮于500微升无菌蒸馏水中，并用血细胞计数板对孢子进行计数。结果表明，该真菌在受感染的芽中以菌丝和分生孢子越冬，在嫩枝病斑中以菌丝和球形厚垣孢子越冬。
