OOSPORE-PRODUCING ALGAL FUNGI 



115 



papilla through which the germ tube grows (acroblastic). 



g. Bremia. 

 Conidiospores without papilla; pleuroblastic. 10. Peroiwspora. 



The most important species of these genera from the standpoint of 

 the plant pathologist are the following enumerated below with their 

 common English names where such have been given. 



English name 



Host plant 



Pythium de Baryantim 



Pythiacystis citriopthora 



Albugo {Cystopus) Candida... 

 Albugo (Cystopus) portulaca; . 



Phytophthora cactorum 



Phytophthora infestans 



Phytophthora phaseoU (Fig. 



44)- 

 Plasmopara cubensis 



Damping-off fungus.. . . 

 Brown rot of lemon.. . . 

 White rust of crucifers. 

 White rust of purslane. 

 Mildew of succulents.. . 

 Late blight of potato.. . 



Plasmopara Halstedii 



Plasmopara viticola ... 



Bremia ladiica 



Peronospora effusa 



Peronospora parasitica Downy mildew of crucifers! 



Peronospara Schleideniana. . . Onion mildew 



Downy mildew of beans. 



Seedlings 

 Lemon fruits 

 Cruciferous plants 

 Portulaca oleracea 

 Cacti, etc. 

 Potato 

 Lima-bean 



Downy mildew of cu- Cucumber 

 cumber. 



and 



Downy mildew of grape. . 

 Downy mildew of lettuce. 

 Mildew of spinach 



Helianthus annuiis 



H. tuberosus 

 Grape vine 



Cynara, Cineraria, Lactuca 

 Spinach 

 Cabbage 

 Onion 



