FUNGOUS DISEASES OF ORNAMENTAL PLANTS. 27 



The change of color in the affected leaf is controlled somewhat by 

 the color of the bloom. In the yellow varieties the foliage often 

 turns to some shade of lemon, while purple is not infrequent in the 

 pink sorts. The bacterial germs most likely enter the leaf through 

 the stomates and, multiplying, spread from there. 



This bacterial disease sickens the whole plant, and there is no 

 fungous growth that breaks through the epidermis as in the rust, 

 etc. Many other plants are liable to similar affections, the most 

 widely known being the twig or fire blight of the pear, apple, and 

 quince trees. 



Fungous Diseases of the Violet. Passing from the carnation to 

 the violet houses, we observe that health does not prevail. Some 

 plants are stunted, others are yellow, while others still have the 

 foliage blotched and spotted in various ways. It will be best for 

 us to single out certain leaves and note the fungi that prey upon 

 .them. 



The Violet Leaf Spot {Cercosiiora Violce Sacc), Figs 2 and 3, as 

 the common name suggests, causes the foliage to become more or 

 less covered with circular spots. There are several fungi causing 

 the spotting of violet leaves, but the Cercospora can usually be 

 detected by the dark centre of the spot due to the multitude of 

 spore-bearing threads that are brown colored. Black moulds of 

 various kinds often flourish upon the dead tissue of the spot and 

 greatly change its appearance. 



Another spotting of the violet leaves is caused by another fungus, 

 namely, Pliyllosticta Violce Desm,, Figs. 4 and 5, of a quite different 

 type from the one above mentioned. By the naked eye, when 

 carefully inspected the Phyllosticta spots are seen to have no dark 

 central area, but scattered over the whole brown spot are minute 

 dark specks in which the spores are borne. The Cercospora spot 

 has the spores on minute aerial branches, but in the Phjdlosticta 

 Spot the spores are formed within flask-like bodies, and ooze out 

 of the open neck when mature. Similar to the Phyllostica are a 

 number of other violet parasites, as Marsonia Violce Sacc. 

 Besides these there are some fungi which cause blotching of the 

 leaf and a general collapse of the whole plant. For example, 

 there is an anthracnose (Glaosporium) of the violet similar to the 

 one mentioned upon the rose. There is a bacterial trouble also, 

 so that the violets are fully supplied with fungous parasites. 



Fungous Diseases of Draccenas. Some of the cultural varieties 

 of Dracaenas, notably the Cordyline terminalis, have failed to 



