116 I. WAHL 



Unpublished data obtained in our laboratory show that 

 production of sclerotia by laboratory cultures in Rhizoctonia' 

 solani could be conspicuously increased by inoculating the 

 nutrient medium with Bacillus subtilis. It was further ascertained 

 by our studies that Mycosphaerella pinocles and Helmintho- 

 sporium teres which incite respectively the most severe diseases of 

 peas and barley in Israel, pass through the summer in this 

 country as a resting mycelium. Most probably many powdery 

 mildew parasites which affect various crops in Israel, as well as 

 Plasmopara viticola, the cause of downy mildew on grapes and 

 other important plant pathogens survive adverse conditions 

 here as resting mycelia. 



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