Lily Diseases 285 



Rot 



Caused by Botrytis paonia Oud. 



This disease, which is usually common on peonies 

 and on lilacs, also frequently attacks the lily of the 

 valley. The causal organism often attacks the pips 

 first; then works its way up to the stems. Infected 

 pips become soft, then become covered with a gray- 

 ish mold, and are later peppered with greenish-black, 

 flat sclerotia. 



Control. The disease is often introduced with in- 

 fected pips which have been previously injured, or 

 kept under poor storage conditions, especially under 

 too high temperatures and moistures. Hence only 

 healthy pips should be used. If the soil becomes in- 

 fected with the causal organism, it should be steam 

 sterilized, or treated with formaldehyde (see pp. 32- 

 43) the former method being preferred. 



Leaf Spot 



Caused by Dendrophoma convallarie Can. 



This leaf spot often destroys entire beds of plants. 

 Little is known of the causal organism or of methods 

 of control. 



Septoria Leaf Spot 



Caused by Septoria majalis Aderh. 



This disease is characterized by a general spot- 

 ting which is unevenly scattered over the leaves. The 

 spots, however, are found mostly on old and faded 



