First report of Alternaria alternata causing leaf spot on Solanum muricatum in Gansu Province, China.
In August 2014, a leaf spot disease on pepino (Solanum muricatum) was observed in Tianzhu County, Gansu Province, China. Disease incidence across the fields (∼667 ha) ranged from 49 to 65%. Disease symptoms included long, elliptical or V-shaped foliar lesions, 1 to 3 cm in diameter, sometimes with a yellow halo and concentric rings. To identify the pathogen, thirty small fragments (3 to 5 mm) excised from the lesion margins were sterilized in 75% ethanol for 40 s, washed with distilled water three times, then transferred to potato-carrot agar and maintained at 25°C in darkness. Based on morphological characteristics, molecular data (sequence analysis of the internal transcribed spacer region, endo-polygalacturonase gene, mixed-linked glucanase precursor gene and a major allergen gene) and pathogenicity tests, the causal agent was identified as A. alternata. This is thought to be the first report of A. alternata causing leaf spots on pepino in China.