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The Bacterial Stalk Rot of Maize Caused by Dickeya oryzae in Taiwan
Fig. 1.　Symptoms of maize bacterial stalk rot observed in the field. (A) Water-soaked blotch on the surface of the stalk at the initial stage of the disease, (B) browning on the stem surface, (C) browning symptom in vascular bundle of the stem, (D) water-soaked browning of the diseased maize ears, and (E) browning and soft rot symptoms on maize kernels.
Fig. 1.　Symptoms of maize bacterial stalk rot observed in the field. (A) Water-soaked blotch on the surface of the stalk at the initial stage of the disease, (B) browning on the stem surface, (C) browning symptom in vascular bundle of the stem, (D) water-soaked browning of the diseased maize ears, and (E) browning and soft rot symptoms on maize kernels.

Author:Chia-Hsin Tsai, Shu-Ling Hwang, Jia-Rong Ku, Mei-Ju Lin, Ching-Yi Lin, Cheng-Ping Kuan, and Chin-Chih Chen*

Abstract:

In 2017, water-soaked brown lesions were found in the stalk of the maize plants in Yuanchang and Huwei township, Yunlin County. The stalks were finally softened by the spreading lesions, resulting in hollowing and lodging of the plants. The bacteria were isolated from the diseased stalk tissues and cultured on nutrient agar. The pathogenicity of the bacteria was verified by Koch’s postulates. The 16S rDNA, gyrB and dnaX gene sequences of the pathogen showed a high identity to Dickeya zeae, and multilocus sequence analysis revealed that the pathogen, D. zeae and D. oryzae were grouped as a clade. However, a publication of a new species of D. oryzae reassigned some D. zeae strains to D. oryzae, and the pathogen was further identified as D. oryzae based on the average nucleotide identity nucleotide of whole genome sequences in our study. This is the first report of maize bacterial stalk rot caused by D. oryzae worldwide. In the host range test, the pathogen could infect potatoes, carrots, onion bulbs, Welsh onions, rice, and cabbages; it therefore showed a potential threat to the agricultural industry. On screening agrochemicals, the 500-fold-diluted 20% oxolinic acid showed the most effective inhibition of the pathogen growth.

Key words:Maize, Bacterial stalk rot, Dickeya oryzae

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Journal of
Taiwan Agricultural Research
Vol. 73, No.3 (2024) ISSN: 2790-086X Vol. 73, No.3 (2024)
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