| Scientific Name | Hyaloperonospora erucae Y.J. Choi & Thines, Eur. J. Pl. Pathol. 151: 553 (2018) |
|---|---|
| Synonyms | - |
| Disease | Downy mildew |
| Taxonomic Rank | |||
|---|---|---|---|
| Order | Peronosporales | Family | Peronosporaceae |
| Host Plant | |||
|---|---|---|---|
| Common Name | Arugula (로켓샐러드(루꼴라)) | Scientific Name | Eruca vesicaria |
| Distribution | Argentina, Korea, USA |
|---|---|
| Characteristics | Lesions commonly present on leaves, causing discoloration of the affected tissues, initially pale green to yellow, later becoming brownish, polyangular, vein-limited, frequently covering larger areas by coalescing. Down present on the lower leaf surface, consisting of dense, whitish, felt-like conidiophore outgrowths forming patches. Haustoria filling the host cell partly to almost completely, lobate. Conidiophores emerging through stomata, up to 16 in a fascicle, hyaline, somewhat stout, straight to slightly curved, (350.0–)368.0–420.0–472.0(–510.0) μm (n = 15); trunk straight, (150–)160–200–240(−270) μm long (n = 50), (10–)12.0–13.5–15.0(−17) μm wide (n = 50), more or less uniform width; basal end slightly swollen, callose plugs absent; branching mostly monopodially, in 7–9 orders, first branching at 1/2–2/3 of conidiophore. Ultimate branchlets mostly in pairs, but rarely single, reflexuous to sigmoid, (7.3–)10.0–14.3–18.6(–25.9) μm long, (0.8–)0.7–2.4–4.1(–10.0) μm wide at the base (n = 30); tip obtuse or subtruncate. Conidia hyaline, subglobose, (17.9–)19.8–21.6–23.4(–26.4) μm long, (15.9–)17.2–18.8–20.4(–24.2) μm wide, l/w ratio (0.74–)1.01–1.16–1.30(–1.41) (n = 30), greatest width median, rarely sub- or supra-median, tip and base rounded; pedicel mostly present as a scar. Resting organs not seen. |
| Notes | Downy mildew of arugula in Korea was first reported as an unnamed Hyaloperonospora sp. because the pathogen was molecularly distinct from H. parasitica (Choi et al. 2010). Subsequent morphological and phylogenetic analyses demonstrated that the pathogen on Eruca sativa was distinct from both H. parasitica and Peronospora erucastri, leading to the description of H. erucae as a new species (Choi et al. 2018). The holotype, KUS-F24009, was collected from E. sativa in Korea. |
| Economic importance | Arugula is an economically important leafy vegetable cultivated primarily for fresh consumption. Downy mildew can markedly reduce leaf quality and marketability. In Korea, severely affected greenhouse-grown arugula was reported to be unmarketable and was abandoned before harvest, demonstrating the potential for substantial economic losses under favorable disease conditions (Choi et al. 2010). |
| References | Choi, Y. J., et al. 2010. Plant Pathol. 59:1165. Choi, Y. J., et al. 2018. Eur. J. Plant Pathol. 151:549. Das, K., et al. 2026. Phytopathology 116:707. |
