Sánchez M E, Lora F, Trapero A
Departamento Agronomía, Universidad de Córdoba, Apdo. 3048, 14080-Córdoba, Spain.
Plant Dis. 2002 Jun;86(6):693. doi: 10.1094/PDIS.2002.86.6.693C.
Cylindrocarpon spp. have been described as producing root rot in Quercus spp. in forest nurseries, mostly when the host plants were weakened (1). To our knowledge, this is the first description of root rot of Mediterranean Quercus (Q. ilex, Q. suber, and Q. faginea) seedlings caused by C. destructans. In spring 2000, heavy mortality of Quercus seedlings was recorded in a nursery in southeastern Spain. The affected plants were 9 months old and growing in the open air in fertilized peat. Symptoms consisted of browning and wilting of leaves, with extensive necrosis of feeder roots. C. destructans (macroconidia averaging 36 × 6 μm, 1 to 3 septate; microconidia 10 × 3 μm; chlamydospores rough, single, or in chains, averaging 9 μm in diameter) was consistently isolated from the necrotic rootlets. Pathogenicity of one isolate from Q. faginea and of a mixture of isolates from the three affected Quercus spp. was determined. Fungal isolates were grown on potato dextrose agar plates for 1 month to allow chlamydospore production, and the inocula were prepared by mixing the contents of three colonized plates with 125 ml of sterile water. Six replicates of 12-month-old Q. ilex and Q. suber seedlings were inoculated by mixing the inoculum from the three plates with the potting medium prior to planting the seedling. All inoculated and control plants (only water added) were grown in a sand-lime-peat soil mixture under greenhouse conditions and watered as needed. After 5 weeks, all the inoculated plants showed extensive root necrosis accompanied by crown symptoms and rapid plant death. No symptoms were evident in control plants, and they produced new rootlets. No significant difference in pathogenicity was noted between the single isolate compared with the mixture of isolates, and the Quercus species did not significantly differ in susceptibility to root rot. C. destructans was easily recovered from necrotic roots. Reference: (1) D. Brayford. Cylindrocarpon. Pages 103-106 In: Methods for Research on Soilborne Phytopathogenic Fungi. American Phytopathological Society, St. Paul, MN, 1992.
柱孢属真菌已被描述为可在森林苗圃中的栎属植物上引发根腐病，大多发生在寄主植物衰弱时（1）。据我们所知，这是首次对由毁灭柱孢菌引起的地中海栎（冬青栎、栓皮栎和欧洲水青冈）幼苗根腐病的描述。2000年春季，西班牙东南部一家苗圃中记录到栎属幼苗大量死亡。受影响的植株为9个月大，生长在露天施肥泥炭土中。症状包括叶片褐变和萎蔫，须根广泛坏死。从坏死的细根中持续分离出毁灭柱孢菌（大型分生孢子平均36×6μm，1至3个隔膜；小型分生孢子10×3μm；厚垣孢子粗糙，单个或成链状，平均直径9μm）。测定了一株来自欧洲水青冈的分离株以及来自三种受影响栎属植物的分离株混合物的致病性。将真菌分离株在马铃薯葡萄糖琼脂平板上培养1个月以产生厚垣孢子，接种物通过将三个已定殖平板的内容物与125毫升无菌水混合制备。在种植12个月大的冬青栎和栓皮栎幼苗前，将来自三个平板的接种物与盆栽基质混合，对六组重复样本进行接种。所有接种和对照植株（仅添加水）在温室条件下的砂 - 石灰 - 泥炭土混合物中生长，并按需浇水。5周后，所有接种植株均表现出广泛的根坏死，伴有冠部症状并迅速死亡。对照植株未出现明显症状，并长出了新的细根。与分离株混合物相比，单一分离株在致病性上无显著差异，且栎属物种对根腐病的易感性也无显著差异。毁灭柱孢菌很容易从坏死根中重新分离出来。参考文献：（1）D. 布雷福德。柱孢属。载于《土传植物病原真菌研究方法》第103 - 106页。美国植物病理学会，明尼苏达州圣保罗，1992年。
