Today I found two specimens of Foeniculum vulgare (fennel) covered with a blanket of sparse white mycelium. Under the microscope I observed a white-semi-hyaline profusely branched mycelium over the epidermis of the host's leaves (=cladodes) but imprgenanting down into the host tissues at regular intervals. The mycelium produced upright perpendicular, simple, 2-3 (4) segmented, 70-100um long branches (conidiophores) were the last cell, fragments away and becomes free as a conidia. The conidia are 30-40um x 10-17um wide, rectangular with truncate sides, finely dotted, an a thick wall, somewhat more thick at one pole forming an eccentric hyphal content.  The surface seams to be rought at the perimiter. No Cleistothecium was observed, perhaps the mycelium is young.


I think it is an Erysiphe spp. but can you confirm or suggest alternative IDs please (Microsphaera spp. ??)