292 PLANT DISEASES 



CHRYSANTHEMUM LEAF BLIGHT 



(Cylindrosporium Chrysanthemi, Ellis and Dearn.) 



Mr. J. Dearness has described a chrysanthemum leaf 

 blight which proved destructive to cultivated plants in 

 Ontario, Canada. Large dark blotches appear on the 

 leaves, which turn yellow, and shrivel. When attacked 

 the flower-buds do not expand. 



Numerous fruiting pustules are formed on the diseased 

 patches ; these produce myriads of long, narrowly spindle- 

 or club-shaped, colourless, septate conidia, which rupture 

 the epidermis of the host, become diffused, and spread 

 the disease rapidly. 



The diseased leaves hang down and lie close to the 

 stem. 



PREVENTIVE MEANS. 'The owners sprayed the plants 

 with all their fungicides, but without any apparent effect 

 on the disease. Doubtless the best course is to burn the 

 affected leaves, or destroy the plant as soon as the disease 

 is observed.' 



FIG TREE DISEASE 



(Libertella ulcer at a, Mas see.) 



This parasite causes the bark to become cankered and 

 cracked, large patches completely disappearing as the 

 disease progresses. When a branch is girdled, the portion 

 above the wound dies, and then produces the fruit of the 

 fungus in minute cavities in the bark, the very minute 

 conidia oozing to the surface in the form of fine hairs, 

 composed of conidia stuck together by a viscid substance, 

 which is dissolved by wet. The conidia are not capable 



