28 
MILDEWS, RUSTS AND SMUTS 
elliptical, 27—30 X 22—24 p,, dingy brownish-violet; 
oospore unknown. 
On leaves of Valeriana officinalis. 
Peronospora schleideni, Unger. Patches of mildew 
effused, rather dense, dingy greyish-lilac ; conidiophores 
large and stout, 250—600 x 12—16 p, emerging from the 
stomata singly or in tufts, branching alternately in a forked 
manner, ultimate and penultimate branches more or less 
curved ; conidia large, broadly pear-shaped, tip blunt or 
somewhat pointed, pale dingy violet, 40—55 X 20—27 p ; 
oospores broadly elliptical or subglobose, wall thin, smooth. 
Syn. Botrytis destructor, Berk. 
Peronospora destructor, Casp. 
Botrytis parasitica, Schleiden. 
Parasitic on various species of Allium. Often very des¬ 
tructive to the cultivated onion (Allium cepa). 
Peronosporu schactii, Fuckel. Forming very dense 
patches, at first white, then gradually changing to dingy 
greyish-violet; conidiophores emerging from the stomata 
singly or in tufts, 250—350 X 7—8 p, repeatedly forked 
above, ultimate and penultimate branches often curved ; 
conidia broadly elliptical, tinged brown, 22—27 X 17—20 p ; 
oospores globose, with a thick, smooth, brown wall. 
Syn. Peronospora hetae, Kuhn. 
Parasitic on plants belonging to the order Chenopodia- 
ceae. 
This parasite is responsible for much injury to Beet 
(Beta vulgaris), also to sugar beet and mangolds. The 
younger central leaves are most frequently attacked, and 
in the case of seedlings growth is materially checked, or 
in many instances killed outright. 
Peronospora rumieis, Corda. Patches of mildew dense, 
broadly effused, dingy greyish-violet; conidiophores 
emerging from the stomata in small tufts, or singly, 450— 
650 X 9 —II p, repeatedly forked upwards, the ultimate 
branchlets spreading ; conidia broadly elliptical, tip very 
blunt and rounded, dingy violet, 26—33 x 16—22 p ; 
oospores unknown. 
83^1. Peronospora effusa, var. rumieis, Fuckel. 
Parasitic on leaves, stem and inflorescence of Sorrel 
(Rumex acetosa), also on Rumex acetosella, R. crispa, etc. 
Peronospora dianthi, De Bary. Patches of mould dense, 
broadly effused, dingy greyish-violet; conidiophores 
