484 



DISEASES OF CULTIVATED PLANTS 



Begin spraying when the leaves are expanding, and repeat 

 at intervals, using self-boiled lime and sulphur compound. 

 Bordeaux mixture cannot be used, as it scorches peach leaves 

 even when much diluted. 



Pierce and Galloway, Journ. MycoL, 7, p. 66. 



FIG. 145. Cercospora circumscissa. i, diseased peach leaf; 2, tuft 

 of conidia, highly mag. 



Cucumber and melon leaf blotch. This destructive pest 

 was first observed in 1896, and for the three or four following 

 years it simply ran riot, killing off whole houses of cucumbers 

 within a few days. It was almost entirely confined to the 

 extensive establishments around London, the produce of 

 which mostly found its way to Covent Garden market. At 

 the present day the disease has practically disappeared. This 

 epidemic may in a sense be looked upon as an artificial 

 creation, inasmuch as it can only extend at a rapid rate under 

 the modern conditions of culture, namely, an atmosphere 



