210 THE PRINCIPLES OF FLORICULTURE 



runs high in the late fall, it causes considerable damage. The 

 microscopical character and reproduction are similar to the leaf- 

 spot of the carnation, as are also the preventives and remedies. 



223. Anthracnose of the rose. Classification: Excipulaceas ; 

 Gloeosporium roses Hals. Anthracnose occurs to a limited extent 

 on outdoor roses, usually attacking the canes, although it may 

 appear on the leaves. It reveals itself in red-purple spots. It 

 rarely attacks indoor varieties. 



224. Microscopical nature and reproduction. The myce- 

 lium ramifies through the tissue of the stems and leaves, and feeds 

 principally in the cells of the cambium layer of the stem, causing 

 a breaking down of the tissue, and a consequent girdling of the 

 stem. It produces conidia which are one-celled and colorless. 

 They germinate easily and the disease spreads rapidly. 



226. Preventives and remedies. To prevent or remedy 

 anthracnose, give the plants thorough drainage, also sufficient 

 food to enable them to grow vigorously. Cut out all affected 

 tissue, and spray the bushes with Bordeaux mixture or copper- 

 carbonate solution. 



226.. Violet anthracnose. Classification: ExcipulaceaB ; Gloeo- 

 sporium violce B. & Br. Anthracnose attacks violet leaves, 

 but causes little trouble on plants otherwise healthy. The 

 fungus spreads from the margin of the leaves over the en- 

 tire surface, the tissue becoming brown and shriveled. Re- 

 productive bodies form in patches on the mycelium underneath 

 the epidermis, and as they mature, the epidermis ruptures and 

 the spores escape. 



The only preventive is to keep the disease tissue picked from 

 the plants. 



227. Mignonette disease. Classification: Hyphomycetes ; 

 Dematieae, Cercospora resedce Fuck. Mignonette disease is a 

 fungus which is very common. It shows itself by small depres- 

 sions of the leaf with brown or yellow borders. Gradually the 

 fungus affects the whole tissue of the leaves and they wither. 



228. Microscopic character and reproduction. The myce- 

 lium spreads throughout the tissue of the leaf and sends out 

 spore-bearing tufts through the stomata. Spores are produced 

 in great numbers. 



229. Preventives. Keeping the diseased tissue cut off, and 

 spraying occasionally with copper-carbonate solutions, will hold 

 the disease in check. 



230. Other diseases of similar character are caused by : 

 Cercospora violce Sacc. on the violets ; Cercospora rosacola 

 Pass, on the rose ; Cercospora althceina Sacc. on the hollyhock. 



