8 THE FUNGI WHICH CAUSE PLANT DISEASE 



knowTi. Seedlings raised in soil inoculated with chopped roots 

 bearing the disease become badly diseased as do also seedlings 

 upon which infected water is poured. 



P. humili Kirk is mentioned by Kirk'' as the cause of club 

 root of hops in New Zealand. 



P. vitis Viala & Sauvageau; * P. calif omica Viala & Sauvageau; ' 

 P. orchidis Massee *" and P. tomato Abbey " have been reported 

 as the causes of serious diseases but their relation to the diseases 

 and even their identity as actual organisms is seriously ques- 

 tioned. ^^-'^ 



Tetramyza Goebel grows upon water plants, notably Ruppia.* 



Sorosphsera Schroter (p. 6) 



Parasitic in the parenchyma of living plants; spores elliptic- 

 wedge shaped, forming a hollow, spherical spore ball. 



One species is found upon Veronica;* a second species has been 

 reported upon tea.^* 



S. graminis Schwartz is reported by Schwartz ^ on the roots 

 of Poa and other grasses where it caused nodules much resembling 

 those of nematodes. 



Spongospora Brunchorst Cp. 6) 



Similar to Sorosphaera but the spores forming a spore ball 

 with open reticulations. 



S. subterranea (Wallr.) Lag.""^' causes the powdery scab of 

 potatoes in Great Britain, Europe and South America. It has 

 been closely studied by Osborne '* who shows it to appear first in 

 the tuber cells as a uninucleate myxamoeba which ultimately 

 develops into a multinucleate amoeboid Plasmodium. 



Sorolpidium Nemec is a new genus with the species. 



S. bets Nemec which is on beets.'** 



Several little known genera, kin to the above, attack algae, 

 fungi, pollen, etc. 



Pseudomonas radicicola, the legume tubercle organism has been 

 by some placed in this order under the name Phytomyxa legumi- 

 nosarum. 



