臺灣農藥科學 第一期

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臺灣農藥科學 第 1 期 142
Bacterial Leaf Spots on Chrysanthemum coronarium
Caused by Pseudomonas syringae
Che-Ming Chang1, Chiou-Chu Su1*
Abstract
Chang, C. M., and Su, C. C. 2016. Bacterial leaf spots on Chrysanthemum coronarium caused by
Pseudomonas syringae. Taiwan Pestic. Sci. 1: 127-142.
In February 2011, Chrysanthemum coronarium leaves with necrotic spot symptoms
were collected from Xiluo Township, Yunlin County in Taiwan. Symptoms began as small
water soaked lesions on the leaf and gradually expanded to become irregular brown spots.
A G(-) bacterial pathogen was isolated from infected leaf tissue. This pathogen was a rod
shaped bacteria that possessed many polar flagella. It was able to induce hypersensitive
reactions in tobacco, produce levan, and utilize sucrose and sorbitol as carbon sources. Using
physiological and biochemical analyses, Biolog identification, PCR analysis, and 16S-23S ITS
rDNA sequence analysis, we identified the pathogen as Pseudomonas syringae. Pathogenicity
was verified by Koch’s postulates. The 16S-23S ITS rDNA sequences of the tested strains were
99.5 ~ 100% identical to the ITS sequences of P. syringae pv. antirrhini, P. syringae pv. tomato,
P. syringae pv. maculicola, and P. syringae pv. lachrymans . We constructed a phylogenetic tree
using the neighbor joining method and determined that the tested strains were clustered with
genomospecies 3 classified by Gardan. We then investigated the ability of 9 agrochemicals to
control this pathogen by disc diffusion assays, and found that Streptomycin + Tetracycline,
Streptomycin, Thiophanate methyl + Streptomycin, Kasugamycin, Copper hydroxid, and
Oxolinic acid had inhibitory activities against the pathogen.
Key words: Pseudomonas syringae, bacterial leaf spot, Chrysanthemum coronarium .
Accepted: September 12, 2016.
* Corresponding author, Email:
1 Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Council of Agriculture. Taichung.