(Casp.) Schroet. ex Wartenw.
SPORANGIA WITH SPORANGIOPHORES occur in conglomerations forming white, dense or loose coatings on the under leaf surface. The fragments of the upper surface of affected leaves, directly above the coatings, became first yellow, then brown.
Branches. Lower branches of the first order frequently produce two, rarely three secondary branches. Terminal branches with one to four final, somewhat irregular branches, 4-10(-25) µm long, 1-2(-5.0) µm thick at the base.
SPORANGIA (s) ovoid, 15-25 x 14-21 µm.
OOGONIA 32-57 µm, with a yellow brown, 2-4 µm thick wall.
OOSPORES 25-42 µm diam, with a smooth or slightly roughened episporium.
PLANT HOST AND DISTRIBUTION. Plasmopara umbelliferarum affects numerous species of the family Umbelliferae. The fungus commonly occurs in Poland and the other regions of the world (Kochman and Majewski 1970).
Kochman J., Majewski T. 1970. Grzyby (Mycota) IV. Glonowce (Phycomycetes), Wroslikowce (Peronosporales). Warszawa, 308 pp.