344 Diseases of Greenhouse Crops 



that the fungus can go back and forth from the 

 apple to the sweet pea and vice versa. Anthracnose 

 begins its destructive work early, even in the seed- 

 ling stage. 



CHiETOMiuM Root Rot 



Caused by Chetomium spirochete Pratt. 

 ' This disease is of minor importance. It is found 

 on plants weakened by poor cultural conditions, such 

 as overwatering. The symptoms of this trouble 

 greatly resemble the injury from Thielavia root rot. 

 The only way, however, to tell them apart is micro- 

 scopically. 



FusARiuM Wilt 



Caused by Fusarium lathyri Taub. 



Symptoms. This disease is of much greater im- 

 portance to greenhouse men than root rot. The 

 writer has known of instances where the disease has 

 ruined the entire crop of indoor sweet peas. After 

 several resowings, the owners gave up in despair any 

 further attempt to grow them. Florists should do 

 everything to prevent the introduction of the dis- 

 ease into the house. In places where this disease 

 has made its appearance the growing of greenhouse 

 sweet peas had to be abandoned within less than two 

 years. The disease produces a sudden flagging of the 

 leaves which is accompanied by a wilting and col- 

 lapse of the seedlings (fig. 70, c). Usually, upon 

 sowing the seed, a fair percentage germinate and 

 reach a height of about eight to ten inches, when they 



