 For instance, the taxonomically correct name of the parasite of the well-known model organism "Arabidopsis thaliana" is "Hyaloperonospora arabidopsidis", not "H. parasitica", whereas the pathogen of "Brassica" has to be called "Hyaloperonospora brassicae".The infection first appears as conidiophores covering the upper and lower leaf surfaces.Other symptoms include lesions on spikelet, fungal growth on leaves, and necrosis on stems and leaves.