400 DISEASES OF PLANTS. 



Puccinia gramiBis will not reproduce itself, but if its spores are sown 

 on the leaves of tlie Barberry they will give rise to the Fungus called 

 ^cidium Berberidis. On the other hand, it has also been proved 

 that the spores of the ^cidium will not reproduce itself, but will give 

 rise to Puccinia graminis. There is thus an alternation of generation 

 in this case, which is remarkable, and in some measure explains the 

 old idea as to the injury caused to Wheat by the Barberry. 



Those Fungi which are developed in the interior of plants, and 

 appear afterwards on the surface, are called entophytic (hrSg, within, 

 and <pt)T6v, a plant). Their minute sporules are either directly applied 

 to the plants, entering by their stomata, or they are taken up from the 

 soil. Many other Fungi grow parasitically on plants, and either give 

 rise to disease, or modify it in a peculiar way. Among them may 

 be mentioned species of Ustilago, Botrytis, Fusisporium, Depazea, 

 Claviceps, Fusarium, and Erysiphe. Puccinia malvacearum makes great 

 havoc among MaUows and Hollyhocks. Fusisporium solani is considered 

 by Martins as the cause of a certain disease in the Potato. In the 

 recent potato-disease Peronospora iufestans, and other Fungi, com- 

 mitted great ravages, spreading their mycelium or spawn through the 

 cells of the leaves and. the tuber, and thus accelerating their destruc- 

 tion. Berkeley, Morren, and Townley, consider the Fungus as the 

 cause of the disease. Others think that there exists, in the first 

 instance, a diseased condition of the cells of the potato, caused by 

 meteorological influences, in connection with high cultivation, and that 

 the subsequent attack of the fungus aggravates the disease and causes 

 rapid decay. Various species of Botrytis also attack the Tomato, 

 Beet, Turnip, and Carrot. A species of Depazea sometimes causes 

 disease in the knots of Wheat. A diseased state of Eye and other 

 grasses, called ergot, owes its production to the presence of Claviceps 

 purpurea. By the action of the fungus the ovary becomes diseased 

 and altered in its appearance, so as to be dark-coloured, and project 

 from the chaff in the form of a spur. Hence the name spurred rye 

 (secale cornutum). The nutritious part of the grain is destroyed, and 

 it acquires certain qualities of an injurious nature. Spontaneous 

 gangrene is the consequence of living for some time on diseased rye. 

 Ergot has been seen in Lolium perenne and arvense, Festuca pratensis, 

 Phleum pratense, Dactylis glomerata, Anthoxanthum odoratum, Pha- 

 laris arundinacea, etc. Quekett found that he could propagate the 

 ergot by mixing the sporules with water and applying this to the 

 roots. 



Extensive disease has been caused to vineyards by the attack of a 

 Fungus called Oidium Tuckeri. The remedy which seemed the most 

 effectual was sulphur. Coffee leaves in Ceylon have suffered from the 

 attack of a Fungus called HemHeia vastatrix. 



Fruits when over-ripe are liable to attacks of Fungi, which cause 



