64 STATE HORTICULTURAL SOCIETY. 



sions, well drained though they be, are more subject to fungous diseases 

 than those upon adjoining knolls. As exceptions to this rule we must note 

 the plants which naturally grow in moist soils, and all such as are subject 

 to the powdery mildews, the development of which is induced in hot, dry 

 summers upon the high land. While other causes may act, it is likely that 

 the dew deposited upon the foliage, being heavier in the depression than 

 upon the elevation, though but a few rods apart, is the principal cause of 

 the diflPerence. 



The amount and character of the plant food supplied to plants has of 

 course much to do with their growth, and, as noted above, this modifies to 

 a considerable extent their susceptibility to the attack of fungi. The 

 injury is caused by the entrance into the tissue of the plants of the roots 

 (hyphae) of the fungi, and if the pants are uninjured, and have made a 

 normal growth, the difficulty of gaining an entrance into the interior will 

 be enhanced. Plants growing in a rich, moist soil, containing large 

 amounts of organic matter, particularly stable manure, are likely to make 

 a loose, watery growth through which the germ tubes can readily gain 

 entrance. On the other hand, the use of fertilizers deficient in nitrogen, 

 but rich in potash and phosphoric acid, will promote a firm growth that 

 will not only be less subject to the attack of fungous diseases, but will be 

 less injured by unfavorable soil or climatic conditions. By the proper use 

 of these fertilizers (ground bone, wood ashes, and potash salts), there is 

 also a decided improvement in the flavor and color of the fruit. 



OPERATION OF FUNGI AND BACTERIA. 



With every precaution in caring for our fruits, destructive fungi often 

 gain admittance, and battle must be waged against them. 



While the number of diseases caused by fungi is legion, the number of 

 bacterial diseases that are known to act as parasites is comparatively small. 

 If in any way the microbes (seeds) of these diseases gain entrance to the 

 interior of the plants, they spread from cell to cell, causing a sort of fer- 

 mentation and destruction of the tissues. These microbes are very minute, 

 requiring the highest power of the microscope to reveal their presence. 

 The affected portions turn brown and the plant has much the appearance 

 of being sunburned. 



In the case of fungi, however, it is often possible with the unaided eye to 

 make out the nature of the disease, as each has its own specific appearance 

 and at some time of their development they form upon or just beneath the 

 surface clusters of seeds known as spores. These may be arranged, one 

 upon the other, in chains, or in groups upon the extremities of long, 

 slender stems, giving the leaves or stems a powdery or, at other times, a 

 velvety appearance. 



When the specific appearance of either fungi or bacteria can be made 

 out with the microscope, the botanist has no difficulty in determining 

 which is causing the disease and what species it is, A person familiar 

 with the appearance of the different diseases can also often do this without 

 the aid of a microscope. While no general rule can be given which will 

 apply in all cases, it may be said that if any portion of a plant takes on a 

 velvety, downy, or powdery appearance, or shows brown spots in which 

 black dots appear, the disease is due to a fungus. On the other hand, if the 

 leaves turn brown without apparent cause, with none of the above indica- 

 tions, it is very likely due to a bacterial disease. 



