Department of Agronomy, Federal Rural University of Pernambuco, 52171-900, Recife, PE, Brazil.
Microb Ecol. 1994 Jul;28(1):101-10. doi: 10.1007/BF00170250.
Curvularia eragrostidis yam leaf spot is a serious concern among the northeast Brazilian yam growing areas. In order to study its biocontrol, bacterial isolates from the yam phylloplane were tested against the pathogen. They were evaluated with respect to the following parameters: (1) inhibition of C. eragrostidis mycelial growth by using paired culture and cellophane membrane methods, (2) inhibition of conidium germination by using a paired suspension test, (3) reduction of disease severity and, (4) persistence of antagonistic action, on plants under greenhouse conditions. From a total of 162 bacterial isolates, 39 showed antagonism to the pathogen in paired culture. The bacteria produced extracellular, nonvolatile, and diffusible metabolites in the membrane cellophane test. Seventeen isolates resulted in more than 75% inhibition of C. eragrostidis mycelial growth. Among them, IF-26 showed the greatest antagonism. The isolates IF-82, IF-88, and IF-109 inhibited pathogen conidial germination, with average inhibition levels of 99.2, 98.2 and 96.2%, respectively. Under greenhouse conditions the antagonists were applied at three different time intervals relative to C. eragrostidis inoculation: 3 days before, at the same time, and 3 days after. IF-82 and IF-88 applied at the same time as pathogen inoculation both reduced disease severity 75%. IF-82 showed the best persistence of antagonistic action, with an average of 96.3%. IF-82, identified as Bacillus subtilis, was the best biocontrol agent for the yam leaf spot disease in this study.
旋花镰孢叶斑病是巴西东北部山药种植区的一个严重问题。为了研究其生物防治，从山药叶面上分离出的细菌分离物被用于对抗病原体。根据以下参数对它们进行了评估：（1）使用配对培养和玻璃纸膜方法抑制 C. eragrostidis 菌丝生长，（2）使用配对悬浮液测试抑制分生孢子萌发，（3）在温室条件下减少植物的病害严重程度和（4）拮抗作用的持久性。在总共 162 个细菌分离物中，有 39 个在配对培养中对病原体表现出拮抗作用。细菌在玻璃纸膜测试中产生了细胞外、非挥发性和可扩散的代谢物。有 17 个分离物导致 C. eragrostidis 菌丝生长抑制率超过 75%。其中，IF-26 表现出最大的拮抗作用。分离物 IF-82、IF-88 和 IF-109 抑制了病原菌分生孢子的萌发，平均抑制率分别为 99.2%、98.2%和 96.2%。在温室条件下，拮抗剂相对于 C. eragrostidis 接种以三种不同的时间间隔施用：接种前 3 天、同时和接种后 3 天。IF-82 和 IF-88 与病原体接种同时施用均将病害严重度降低了 75%。IF-82 表现出最好的拮抗作用持久性，平均为 96.3%。IF-82 被鉴定为枯草芽孢杆菌，是本研究中山药叶斑病的最佳生物防治剂。
