280 STATE HORTICULTURAL SOCIETY. 



The body of a fungus consists of a mass of minute, thread-like tissue, to 

 which the name of mycelium has been given. These may be found either 

 upon the exterior of plants, in which case they send short, root-like suckers 

 down into the tissues below and thus take up their food, or they may pene- 

 trate the bodies of their hosts, where they suck out the sap from the cells 

 and cause their destruction. While most common on the leaves, all parts 

 of plants are subject to attack. When they have reached a certain stage 

 of development, arrangements are made for reproduction. In most cases, 

 a number of short branches are sent out upon which round or oval spores 

 are formed, the number in most cases being very large. These spores are 

 distributed by the wind, and in various other ways, and if they fall upon 

 a moist place on a plant of the same kind a germinating thread will be sent 

 out and a new mass of mycelium will be formed. In many cases only a 

 few hours will elapse from the time the spore drops from its stalk until it 

 has germinated and become a new fungus. These summer spores can not 

 survive great changes in temperature and moisture and, to carry the fungus 

 over winter, another form known as winter spores is developed by most 

 plants, as the end of the season approaches. These as a rule have thick, 

 firm coverings, and are often buried deep in the tissues of the plants. 



When spring approaches, the spores escape from their coverings and the 

 life of the new crop of fungi begins. While in some cases the mycelium 

 survives the winter, there is also, in most cases, a crop of winter spores by 

 which the disease can be distributed in the spring. 



While the same conditions do not favor the development of all kinds of 

 fungi, some thriving best when it is hot and dry while with others a cool, 

 moist atmosphere seems most favorable to their development, a certain 

 degree of moisture is necessary for the germination of all forms. 



The fungi cause injury to the plants in various ways, as they not only 

 rob the tissues of the food designed for the nourishment of the plant, but, 

 as the cells are ruptured, a large amount of water will be lost by evapora- 

 tion from the tissues. Oftentimes a large amount of the leaf surface of a 

 plant is involved, and, being unable to perform its normal functions, the 

 assimilating powers of the plant are weakened. When large areas of new 

 stems are involved, the drying out is so deep that the circulation is nearly 

 if not quite cut off and it may result fatally to the plant. 



A few of the fungi, such as the powdery mildews, live upon the exterior 

 of plants and can be readily reached by fungicides, but the great majority 

 of them penetrate the epidermis on germinating, and are then beyond the 

 reach of any external application. For all such inside feeders, or endophytes, 

 the principal means at hand for combatting them is by the covering of the 

 plants with some material that will destroy the spores and prevent them 

 from sending their germ tubes into the plants. Many forms of fungicides 

 have been tried, but the ones that have been found most efficacious are 

 some of the salts of copper. 



In most cases nothing more can be done, but there are some diseases 

 which work in such a way that much can be done to prevent their spread 

 by destroying the iafected portions. When this can be done without too 

 great trouble, considerable good will be done. 



The bacteria are parasites and saprophytes of an even lower order than 

 the fungi. They are extremely minute, being so small that they can only 

 be seen with the highest powers of the microscope, and consist each of a 

 single cell, although, as they multiply by fission, a single individual sep- 



