Gally T, González B, Sobero Y Rojo M P, Lori G
Depto. de Tecnología, Universidad Nacional de Luján, CC No. 221, 6700 Luján, Buenos Aires, Argentina.
C.I.C., Fac. Ciencias Agrarias, Universidad Nacional de La Plata, Av. 60 y 119, 1900 La Plata, Argentina; E-mail: <
Plant Dis. 1998 Sep;82(9):1063. doi: 10.1094/PDIS.1998.82.9.1063A.
Soybean (Glycine max) is an important crop in the northern area of the province of Buenos Aires, Argentina. Phomopsis spp. and Fusarium spp. are the prevalent pathogens in soybean seeds. Infection levels for both pathogens can be greater than 50%. In seedlings growing in sand or soil, both pathogens produce rotten lesions on cotyledons and hypocotyls, but over the past 2 years a plumele soft rot has also been observed associated with detached teguments that was previously demonstrated to be caused by Fusarium spp. (1). In 1996, seeds with a germination level lower than 82% were selected from an assay including 22 cultivars, and examined for the presence of Fusarium spp. The infection level ranged from 2 to 16%, and the Fusarium spp. present were identified as F. equiseti, F. oxysporum, and F. pallidoroseum. After each Fusarium sp. was cultured on potato dextrose agar, a conidial suspension was prepared and adjusted to 1.8 × 10 conidia per ml. This inoculum was sprayed on water-soaked paper, in petri dishes, and good quality soybean seeds were placed on the paper, with 400 seed for each Fusarium sp. The petri dishes were maintained at 26°C for 24 h. Control seeds were plated on water-soaked paper. Inoculated seeds were sown in sand with a water content of 16% wt/wt, covered with polyethylene bags, and incubated for 7 days in a growth chamber at 26°C and a 12-h light period. All the samples inoculated with the three Fusarium spp. exhibited seed rot, seedlings with cotyledon and hypocotyl lesions as described previously (2), but also plumele soft rot. Control seedlings remained symptomless. This is the first report confirming that the characteristic plumele soft rot of soybean seedlings is a nonspecific symptom associated with F. equiseti, F. oxysporum, and F. pallidoroseum. References: (1) B. González et al. ISTA-PDC Symp., 2nd. 1996. (2) G. S. Saharan and V. K. Gupta. Plant Dis. Rep. 56:693, 1972.
大豆（Glycine max）是阿根廷布宜诺斯艾利斯省北部地区的一种重要作物。拟茎点霉属（Phomopsis spp.）和镰孢菌属（Fusarium spp.）是大豆种子中的常见病原体。两种病原体的感染率都可能超过50%。在沙土或土壤中生长的幼苗中，两种病原体都会在子叶和下胚轴上产生腐烂病斑，但在过去两年中，还观察到一种与种皮脱落相关的胚芽软腐病，此前已证明是由镰孢菌属引起的（1）。1996年，从包括22个品种的试验中挑选出发芽率低于82%的种子，检测其中镰孢菌属的存在情况。感染率在2%至16%之间，所存在的镰孢菌属被鉴定为尖孢镰孢（F. equiseti）、尖镰孢（F. oxysporum）和淡玫瑰色镰孢（F. pallidoroseum）。将每种镰孢菌在马铃薯葡萄糖琼脂上培养后，制备分生孢子悬浮液并调整至每毫升1.8×10个分生孢子。将这种接种物喷洒在培养皿中浸湿的滤纸上，然后将优质大豆种子放在滤纸上，每种镰孢菌接种400粒种子。将培养皿在26°C下保持24小时。对照种子播种在浸湿的滤纸上。将接种后的种子播种在含水量为16%（重量/重量）的沙子中，用聚乙烯袋覆盖，并在生长室中于26°C和12小时光照周期下培养7天。所有接种了三种镰孢菌的样品都出现了种子腐烂、幼苗子叶和下胚轴出现如前所述的病斑（2），同时也出现了胚芽软腐病。对照幼苗无症状。这是第一份证实大豆幼苗特有的胚芽软腐病是与尖孢镰孢、尖镰孢和淡玫瑰色镰孢相关的非特异性症状的报告。参考文献：（1）B. González等人，ISTA - PDC研讨会，第二届，1996年。（2）G. S. Saharan和V. K. Gupta，植物病害报告56:693，1972年。
