138 



PHYCOMYCETEAE 



Fig. 45. Peronosporales. (A) Family Albuginaceae. Albugo portidacae (DC.) 

 Kuntze. Conidiophores and conidia. (B-F) Family Peronosporaceae. (B) Basidiophora 

 entospora Roze & Cornu, conidiophores and mature oospore. (C) Rhysotheca australis 

 (Speg.) Wilson, conidiophore. (D) Peronospora ficariae Tul., conidiophore and oogone 

 with oospore. (E-F) Bremia lactucae Kegel. (E) Tip of conidiophore branch. (F) 

 Conidia showing germination by germ tube and by zoospores. (A-E, after Berlese: 

 Icones Fungorum, Padua. F, after Milbrath: /. Agr. Research, 23(12) :989-994.) 



other composites; and A. ipomoeae-panduranae (Schwein.) Swing., on the 

 sweet potato (Ipomnra batatas (L.) Lam.) and related plants. In most 

 cases the disease caused is of minor importance. (Figs. 44 and 45 A.) 



Family Peronosporaceae. The Peronosporaceae, Hke the Albu- 

 ginaceae, differ from the Pythiaceae in their strictly parasitic habit, the 

 mycelium always being intercellular with haustoria penetrating the ad- 



