The Korean Soclety of Plant Pathology : M ; 현장연구 : M-13 ; Powdery mildew caused by Erysiphe heraclei on funnel in Korea

Fennel (Foeniculum vulgare Mill.), belonging to the family Apiaceae, is wide-ly cultivated and used as a culinary spice (Diao 2014). In October 2014, fen-nels showing typical symptoms of powdery mildew were found with 100% disease incidence in a plastic greenhouse in Namwon City, Korea. Symptoms first appeared as white colonies, which subsequently showed abundant my-celial growth on the leaves, often covering the whole surface. Infected plants were mainly unmarketable due to signs of white fungal growths on leaves and stems. Severe infections often caused leaf withering and premature senescence. The fungi hyphae were septate, branched, and 4 to 7 μm wide. Appressoria were multilobed to moderately lobed, and solitary or in opposite pairs. Conidiophores were cylindrical, 80 to 140 × 8 to 10 μm, and composed of 3 to 4 cells. Foot-cells of the conidiophores were straight to sub-straight, cy-lindrical, and 25 to 50 μm long. Singly produced conidia were oblong-elliptical to oblong, occasionally ovate, 30 to 50 × 12 to 16 μm with a length/width ratio of 2.4 to 3.6, had angular/rectangular wrinkling of outer walls, and lacked distinct fibrosin bodies. Germ tubes were produced on the perihilar position of conidia. Primary conidia were apically conical, basally truncate, and gener-ally smaller than the secondary conidia. Chasmothecia were not found. These structures described above were typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The specific measurements and morpho-logical characteristics were consistent with those of E. heraclei DC. (Braun and Cook 2012).