276 The Spraying of Plants. 



the formation of small dark-brown spots upon the foliage. 

 The affected areas increase in size until the leaves are so badly 

 affected that they fall to the ground. It is only within the last 

 few years that the disease has become serious. A leaf blight, 

 caused by Cylindrosporium Chrysanthemi, E. & D., closely resem- 

 bles the leaf spot and is with difficulty distinguished from it 

 without the aid of a microscope. 



New Leaf Spot (Phyllosticta Chrysanthemi, E. & D.). De- 

 scription. This is another recent disease affecting chrysanthe- 

 mums. It forms upon the leaves rather large purplish-brown 

 areas. These appear soft and velvety upon the surface. When 

 a leaf is severely attacked the portions apparently unaffected 

 turn yellow, and the value of the leaf to the plant is de- 

 stroyed. 



Treatment. Although these diseases have not been exten- 

 sively treated, it seems very probable that they should be kept 

 in check without much difficulty. Bordeaux mixture has in a 

 few cases been used with apparent success ; and if the applica- 

 tions are thoroughly made, and repeated at intervals of two or 

 three weeks, there is every reason to believe that the plants 

 may be kept comparatively free from disease. But these fungi 

 have also proved to be troublesome in the cutting bench, and 

 here their treatment is more difficult. Only healthy stock 

 should be used for propagation, and if the plants have been 

 well grown this should not be difficult to find. If the diseases 

 do appear among the cuttings, the use of fungicides will un- 

 doubtedly be of value in checking the spread of the parasites. 



CORN. 

 FUNGOUS DISEASES. 



Smut (Ustilago Maydis, DC.). Description. This fungus 

 attacks all parts of the corn plant above ground. It forms 

 large black swellings on the stalks, ears, and tassels, being espe- 

 cially common in the first two places named. It is less fre- 

 quently found upon the leaves. It does the greatest damage 

 in the ear, for it not only destroys much of the grain, but 

 that which remains serves well as a source of infection to the 

 crop grown the following year, provided any of it is used for 

 seed. 



