Inoculation of Curvularia eragrostidis in yam plants (Dioscorea alata) cv. São Tomé

ABSTRACT The aim of this study was to select the method of C. eragrostidis inoculation in yam seedlings (Dioscorea alata) cv. São Tomé to determine the infection and the latency period. The isolate of C. eragrostidis was obtained from yam leaves showing symptoms of the disease. Plants aged 45 days old, cultivated in a greenhouse, were inoculated with the pathogen, as follows: T1 – Spore suspension (1x10 conidia mL-1); T2 – Colonial disks of 10mm fixed with adhesive tape (two on the abaxial surface and one on the adaxial surface); T3 - Brushing of spores; T4 - Cotton soaked in the inoculum suspension; T5 - Control (plants sprayed with sterile distilled water). After 72h of inoculation, the disease incidence was daily evaluated and the severity was assessed on the 15th day. The obtained results revealed that the spore suspension spraying method was more efficient for C. eragrostidis inoculation in yam seedlings, causing the first symptoms to appear from the third day after inoculation.

摘要 本研究旨在筛选针对参薯（Dioscorea alata）品种‘圣多美’（São Tomé）实生苗的C. eragrostidis接种方法，以明确其侵染过程与潜伏期。该病原菌菌株分离自表现出典型病害症状的山药叶片。选取种植于温室的45日龄参薯实生苗，采用以下5种方式接种病原菌：T1——孢子悬浮液喷雾接种（浓度为1×10个分生孢子·mL⁻¹）；T2——以胶带固定直径10mm的菌落圆盘（叶背2个、叶面1个）；T3——孢子刷涂法；T4——浸有接种悬浮液的棉团接种法；T5——对照组（喷施无菌蒸馏水）。接种72小时后，每日调查病害发病率，于接种后第15天评估病情严重度。研究结果表明，孢子悬浮液喷雾接种法对参薯实生苗的C. eragrostidis接种效果最优，首次病害症状于接种后第3天即可观测到。