274 FRUIT PESTS 



poison cannot be placed where it will be effective. Many 

 kinds of washes have been recommended, but few of them 

 prove satisfactory. The fruit grower usually examines 

 his trees every spring and fall, and digs out all borers that 

 he finds working in the trunks. The soil should be re- 

 moved from the base of the tree about a week or two be- 

 fore digging out the borers. Their presence will then be 

 indicated by fresh castings. 



FRUIT DISEASES 



The fruit grower has to contend also with plant diseases. 

 These may be classified under two heads, fungous and 

 bacterial diseases. 



Fungous Diseases. A fungus is a plant living upon 

 other plants. It contains no chlorophyll and, therefore, 

 cannot manufacture food for itself, hence it must live by 

 appropriating food from other plants. Some fungi live 

 upon the fruit, others upon the foliage, and others upon 

 the bark of the branches, while still others live upon two 

 or more parts of the tree. Nearly all scabs, smuts, mil- 

 dews, rots, and blights are fungous diseases. For the 

 control of these it is well to know something of their life 

 history. Fungi reproduce by means of minute spores, 

 which are somewhat similar to seeds. These spores, car- 

 ried by the wind, insects, or rain, alight on the surface of a 

 leaf or fruit and if conditions are favorable germinate 

 there. Most spores will not germinate unless moisture is 

 present. The spores upon germinating produce small 

 rootlets which penetrate the surface of the leaf or skin of 

 the fruit and spread from cell to cell in every direction, 

 feeding upon the tissues within. When a fungus has reached 

 this stage, it is impossible to destroy it with a spray, since 



