Soft Rot of Onion Bulbs Caused by Pseudomonas marginalis Under Low Temperature Storage

Kim, Yong Ki; Lee, Seung Don; Choi, Chung Sik; Lee, Sang Bum; Lee, Sang Yeob

The Plant Pathology Journal 2002;18(4):199-203.
Published online August 31, 2002.

Soft Rot of Onion Bulbs Caused by Pseudomonas marginalis Under Low Temperature Storage

Yong Ki Kim, Seung Don Lee, Chung Sik Choi, Sang Bum Lee, Sang Yeob Lee

Abstract

Soft rot occurred severely in onion bulbs stored under low temperature (5℃) in storage houses at Changyoung, Kyungnam province, Korea in early 2000. Water-soaking and yellowish-brown lesions initially appeared on the outside scales of diseased onion bulbs, gradually progressing into the inside scales. Among the bacterial isolates obtained from the lesions, K-2 isolate was found to be responsible for the disease, which grew at a temperature range of from 0º to 36℃ with optimum temperature of 30º-33℃. However, it showed strong pathogenicity to onion bulbs at 25ºand 5℃ at 3 days and 2 months, respectively. The bacterium also caused soft rot on potato and showed hypersensitive reactions to tobacco and potato. The causal bacterium of onion soft rot was identified as Pseudomonas marginalis based on morphological, biochemical, and physiological characteristics including LOPAT. Soft rot in onion under low temperature storage caused by P. marginalis has not been previously reported.

Key Words: Low temperature, onion, Pseudomonas marginalis, soft rot