350 Diseases of Greenhouse Crops 



up of the summer spores of the fungus. Later, the 

 outer scales become covered with small hard fungus 

 bodies, sclerotia (fig. 72, d.). Besides the tulip, the 

 same disease may also attack Narcissus pseudo-nar- 

 cissus, Galanthus nivalis, and Crocus vernus. 



The Organism. The causal organism has two 

 spore stages, the summer stage, Botrytis parasitica 

 Cavara (fig. 72, c), and the winter or ascus stage, 

 Sclerotinia parasitica Massee.* 



Control. Since the causal organism is introduced 

 with the soil, steam sterilization of the latter is rec- 

 ommended. All infected material should be de- 

 stroyed by fire. Care should be given to the water- 

 ing and ventilation. 



ScLEROTiuM Rot 



Caused by Sclerotium tuUparum Kleb. 



The rot of tulip bulbs which is caused by the 

 above organism has not as yet attained economic 

 importance in this country. Very little is known of 

 the disease or of the causal organisms. Hopkins f 

 states that the sclerotia of Sclerotium tulipdrum are 

 much larger than those of Botrytis parasitica, the 

 latter of which are small, the size of a pin head. 



Sclerotium Rot, 



Caused by Sclerotium tulips Lib. 



This trouble was found by Seaver + on out-of- 



•Massee, G., A Text-book of Plant Diseases: 158-159, 1903 

 (London). 

 t Hopkins, E. F., Phytopath. 8 : 75, 1918. 

 4: Seaver, F.l.., Jour. N. Y. Bot. Gard. 18:186-188, 1917. 



