¹Division of Applied Biology, Chemistry and Food Science, College of Agriculture, Chungnam National University, Taejon 305-764, R. Korea
²Korea Research Institute of Bioscience and Biotechnology, Taejon 305-600, R. Korea

*shunyu@cnu.ac.kr

Accepted for publication 10/10/2000

A leaf blight disease of blackberry-lily (Belamcanda chinensis) was observed during September 1999, in a garden in Kyonggi district, Korea. Further survey of the blackberry-lily in gardens in the district of Chungnam and Kyongbuk revealed that the disease was widespread and under moist conditions was responsible for considerable damage.

Leaf lesions were elliptical to irregular oval in shape, yellow brown to dark brown, sometimes concentrically zonate with diffuse margins frequently surrounded by light coloured haloes. Infection often started at the leaf tips and progressed to the base of leaves as symptoms developed (Fig. 1). In severe infections, lesions enlarged and coalesced, resulting in blighting of the leaves.

Figure 1. Leaf lesions caused by A. iridicola on blackberry-lily.	Figure 2. Conidia of A. iridicola (Bar=30µm)

A species of Alternaria having conidia with prominent beaks and spores produced singly or in chains of 2-4 was consistently observed on and isolated from the lesions of the plant. On PDA the fungus grew slowly, colonies reaching about 35mm in diameter in 7 days when incubated at 25°C. Conidiophores from naturally infected blackberry-lily were more or less cylindrical, arising singly or in bundles of 2-5, pale yellow to pale brown, straight or flexuous, almost colourless at the tip, sometimes geniculate with one to several conidial scars and measuring up to 120×5-7.5µm. The conidia from the host were obclavate to long ovoid, mostly straight or slightly curved, pale olive or pale brown and smooth. The number of transverse septa varied from 3-10, and 1 to several longitudinal septa were present. The conidia were slightly or sharply constricted at the transverse septa and measured 20-95×15-35µm with beaks which measured up to 90µm (Fig. 2). The isolates were identified as Alternaria iridicola J. A. Elliott (Elliot, 1917, Shimasaki, 1930). A. iridicola has been reported on Iris species in the central United States (Anonymous, 1960) and Japan (Anonymous, 1980), but little is known of this pathogen from Korea.

Pathogenicity tests were carried out in the greenhouse on 2-month-old plants of blackberry-lily, Iris germanicola and Iris nertschinskia. These were sprayed with a conidial suspension (5×10⁴ conidia per ml) of Alternaria isolated from diseased blackberry-lily; control plants were sprayed with sterilised water. Plants were covered with polyethylene bags for 2 days. Disease symptoms on blackberry-lily and Iris species appeared 3 days after inoculation. Symptoms on Iris leaves were similar to those on blackberry-lily. Control plants did not develop symptoms. A. iridicola was consistently re-isolated from inoculated plants. This is believed to be the first report of A. iridicola on blackberry-lily.

References

Anonymous, 1960. Index of Plant Diseases in the United States. USA : United States Department of Agriculture : USDA publishing no. 165. (Agriculture Handbook Series.).

Anonymous, 1980. Common Names of Economic Plant Diseases in Japan. Vol. 2. Japan : The Phytopathological Society of Japan.

Elliot JA, 1917. Taxonomic characters of the genera Alternaria and Macrosporium. American Journal of Botany 4, 439-476.

Shimasaki Y, 1930. A disease of Iris caused by Macrosporium, Journal of Plant Protection (Tokyo) 17, 459-463 (in Japanese)

The British Society for Plant Pathology