DISEASES IN GREENHOUSE 113 



sweet pea. In his report before that so- 

 ciety, Chittenden gives an accurate de- 

 scription of the "streak," so that there can 

 be no doubt that he had the disease well in 

 mind, that is, he described it as a stem dis- 

 ease. Chittenden, however, attributed 

 "streak" to Thielavia bflsicola Zopf. In 

 this Chittenden erred, for streak has since 

 been found to be caused by a bacterium. 

 Massee,^ too, made the same mistake, for 

 he also considered Thielavia as the cause 

 of "streak." Streak however is different 

 from Thielavia root rot. 



Symptoms. Plants severely infected 

 with Thielavia have practically no root 

 system, since the roots are destroyed by the 

 fungus as rapidly as they are formed (fig. 

 12) . All that is left of the root system is 



* Massee, George, A disease of sweet peas, asters and 

 other plants. Roy. Bot. Gard. Kew Bui. of Misc. In- 

 form. No. 1:44-52, 1912, London. 



