26 STATE HORTICULTURAL SOCIETY 



252. P. polygon!, Thuem. 



On Polyyonum aviculare and on P. dumertorum, var. 

 scandens. 



253. P. potentate, DeBy. 

 On Potent ilia norvegica. 



254. P. pygmaa, Unger. 



On Anemone dichotoma. 



255. P. sordida, Berk. 



On Scrophuteria nodosa. 



256. P. trifoliorum, DeBy. 



On f-icia americana and on Astragalus canadensis. 



257. P. ttrfa'coj, DeBy. 



On Laportea canadensis. 



258. P. viticola, DeBy. 



On TWs raparia. On cultivated grapes. Brown rot. 



259. P. tncwB, (Berk.) DeBy. 



Abundant in latter part of May and early June on Vicia 

 americana. 



260. P. arthuri, Farlew. 

 Abundant on (Enothera biennis. 



261. P. effusa, (Grev.) Rahenh. 



Abundant on Ckenopodium album in May and June. 



262. P. euphorbia, Fuckel. 



Abundant on Euphorbia preslii and #. macuteta. 



263. P. cite, Fuckel. 



Abundant on Plantago major. 



264. P. cubensis, B. & C. 



Mildew of squash and cucumbers, usually under glass. 

 PYTHIUM, Pringsh. 



265. P. de baryanum, Hesse. 



Attacks seedling plants, and is called by gardeners 

 "damping-off." 



