236 NEBRASKA STATE HORTICULTURAL SOCIETY. 



uncommon. In this trouble the parasite enters the stem and grows 

 rampantly in the water vessels or ducts until they are completely plugged, 

 and the supply of water to the foliage is interrupted. Often the first 

 indication of the presence of this disease is the sudden wilting of the 

 platit, no previous warning symptom having made its appearance. 



In some diseases, the death of parts of the plant, as leaves, twigs, 

 stems, flowers, etc., is the firet symptom that is observed. In the fire- 

 blight of pears and apples the young terminal twigs with their leaves 

 and flowers are killed and even large branches are involved and succumb. 

 The leaves turn brown and dry up while still hanging upon the tree and 

 the twig will be found to be dead down to a certain point, which marks 

 the advance of the bacterium which is the cause of the disease. In this 

 disease small, gummy drops, which consist of myriads of these bacteria, 

 often ooze out from the dead bark. Sometimes the blossoms of plums 

 turn brown and die prematurely as if blasted by frost or fire. This 

 blighting of the blossoms is due to the same organism, the brown rot 

 fungus, which causes the rotting of peaches, plums, cherries and some- 

 times apples. 



In many diseases a more or less marked reduction in size, a dwarfing 

 or atrophy of the whole plant or some of its organs, is evident. A 

 crippled and deformed individual or a poorly-developed organ, with im- 

 poverished nutrition, is the result in many cases. The dwarfing or 

 reduction in size of apples by attacks of scab is often prominent. Many 

 apples seriously affected do not reach over one-fourth the natural size, 

 while others are gnarly and deformed, due to localized atrophy of the 

 tissues of the fruit. The same may be said of apples affected by "cedar 

 rust," although perhaps the effect is not as striking as in apple scab. In 

 a disease of the peach, known as "little peach," a marked reduction in 

 size of the fruit is one of the attendant and characteristic symptoms. 

 Every farmer is familiar with the shrunken and shriveled appearance 

 of wheat from badly rusted fields. The energy of the plant is sapped 

 by the rust fungus, and as a result the grains are poorly developed, 

 lessening the yield and quality of the crop. The dwarfing of stem, 

 leaves, roots, flowers, or flower parts, or even the complete arrest of 

 seed development is often the result of the inroads of some parasitic 

 fungus. 



While a large number of fungi produce more or less extensive atrophy 

 or dwarfing of parts of their host, others cause abnormal enlargements 

 of organs or parts of organs. The so-called "plum pockets" or "fools" 

 is a striking illustration of hypertrophy. In this disease the outer layers 

 of the fruit become thick and fleshy, while the pit remains undeveloped, 

 causing the modified fruit to be hollow, hence the other common name 

 of "bladder plums," which is sometimes employed. The flower parts of 

 the radish and related plants are frequently enlarged and deformed 

 as a result of the attacks of white rust, while the catkins of some of 

 our trees show striking modifications of size and color due to the 



