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SOME NOTES ON THE SOUTH AFEICAN ERYSIPHACEAE. 
By Ethel M. Doidge, DSc, RL.S. 
(Read April 21, 1915.) 
(Plates XXX.-XXXV.) 
The fungi belonging to the group Erysipliaccae, generally known as 
the " powdery mildews," are responsible for a number of very widespread 
diseases in this country, and in some cases cause serious damage. It is a 
well-known fact that in Europe the mildews on cultivated plants form 
perithecia comparatively seldom, and this condition prevails to an even 
greater extent in South Africa, therefore the work of accurately classifying 
these fungi is rendered difficult, as although Oidium spp. have been 
reported on a wide range of indigenous host plants, on these, too, 
perithecia are seldom found. 
In his Monograph of the Erysipliaceae, Salmon has traced the identity 
of a number of these mildews which seldom form perithecia on cultivated 
plants, and in the accompanying list these oidial stages are provisionally 
assigned to the species to which they most probably belong. 
The apple mildew {Poclosphaera leucotriclm (Ell. k Ev.) Salm.) is 
rather a serious pest in the orchards of the Orange Free State ; trees 
four and five years old are seriously attacked. From an orchard in that 
province were obtained twigs bearing numerous perithecia of the fungus, 
and the identity of the pest was thus established ; they were most 
plentiful on the variety known as Rome Beauty. Several outbreaks of the 
apple mildew have also been reported from various localities in the Cape 
and Transvaal Provinces. 
SpliaerotJieca pamiosa Lev., the rose mildew, is prevalent wherever the 
rose is cultivated, and is very common and widespread in South Africa ; 
indeed in some localities it is almost useless to cultivate susceptible 
varieties such as the Crimson Rambler. Although diseased plants 
have been under observation at all seasons during the past two or three 
years, the perithecia of this fungus have not been observed. There 
is only one case of the occurrence of this fungus on the peach {Primus 
persica). 
According to Salmon the perithecia of vine mildew {Oidium Tuckeri) 
