荔枝酸腐病之發生及病原菌特性

本省荔枝酸腐病主要是由Geotrichum candidum及G. ludwigii所引起，在荔枝園土壤及果實皆可分離到病原菌，病原菌除了可感染荔枝外，尙能感染印度棗、龍眼及楊桃等果實。G. candidum於馬鈴薯葡萄糖瓊脂培養基上之菌落爲白色，表面粉狀或近似細絨毛狀，菌絲無色，有隔膜，呈二或三分叉生長，節孢子(arthrospores)圓桶狀或橢圓形，孢子大小爲5-15 × 4-8 μm ,於28 C恆溫箱培養，3小時後節孢子即開始發芽，6小時後有隔膜產生，節孢子於8C 以下，40 C以上不發芽，28-32 C爲最適發芽溫度；而G. ludwigii之菌落則爲乳白色，似酵母菌，菌絲無色，有隔膜，節孢子圓桶狀或橢圓形，孢子大小爲5-35 × 5-10 μm ,於28 C恆溫箱培養，4小時後節孢子即開始發芽，7小時後有隔膜產生，節孢子於12C以下，40C以上完全不發芽，28-32 C發芽率最高。此兩種病原菌在8 C以下或36 C以上生長緩慢，最適生長溫度爲28-32 C，在不同之酸鹼度下生長適應性極廣，於pH3-11皆可生長，pH6-9時最適生長。

關鍵字

荔枝酸腐病

並列摘要

Sour rot of litchi severely occurred at Shuili. Chichi, Nantou, Pinglin. Fenyuan, Taiping and Chia-I in recent years. The causal organisms were identified to be Geotrichum candidum and G. ludwigii. Both pathogens were widespread in the orchard soils in Taiwan. Based on pathogenicity tests, the pathogens not only caused sour rot of litchi but also caused fruit rots of longan, Indian jujube and star fruits. Colonies of G. candidum on PDA medium, effuse, fari nose and lanose. Hyphae dichotomous or trichotomous branching. Arthrospores cylindrical, ellipsoidal, hyaline, smooth, 0-1 septa, 5-15 x 4-8 μm. The arthrospore germination and septa formation were found on PDA after incubation at 28 C for 3 and 6 hr, respectively. The optimal temperatures for arthrospore germination were from 28 to 32 C. while no germination was observed below 8 c and above 40 C; Colonies of G. ludwigii on PDA effuse, whitish Arthrospores cylindrical. ellipsoidal. hyaline. smooth. 5-35 x 5-10 μm. The arthrospore germi nation and septa formation were found on PDA after incubation at 28 C for 4 and 7 hr, respectively. The optimal temperatures for arthrospore germination were from 28 C to 32 C, while no germination was observed at temperature below 12 C and above 40 C. The optimal tempera tures for the growth of G. candidum and G. ludwigii were from 28 C to 32 C. and the optimal pH values were from 6 to 9.

並列關鍵字

Litchi sour rot ； Geotrichum candidum ； G. ludwigii

國際替代計量

荔枝酸腐病之發生及病原菌特性

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