154 Principles of Plant Oulture. 



271. The Injurious Parasites of plants are Very Numer- 

 ous and a scientific cliissification. of them is beyond the 

 limits of this work. We shall only endeavor to arrange 

 the different j)arasites into gronps based on their manner 

 of working injury and the methods by which they may 

 be controlled. 



AA'ith reference to the character of their injury and 

 the preventi\'es used, as well as in their natural character- 

 istics, plant i)aiasi(es are readily separable into two great 

 classes, viz., animal and vegetable i)arasites. These 

 classes will be considered in their order. 



A — Plants as Aj-i-ectku r.r Axijial Pakasites 



a — By quadrupeds and birds. The four-footed ani- 

 mals that injure cultivated crops nearly all belong to the 

 class known as rodents, which includes mice, gophers, 

 rabbits, wood chucks, moles etc. These may usually be 

 controlled by trapping, shooting, or poisoning, or by pro- 

 tecting the plants. 



272. Damage from Mice to orchard and nursery trees 

 is very common. Jlice are usually most troublesome on 

 sod ground covered with snow, especially beneath snow 

 banks, hence all grass should be removed in autumn 

 from the immediate vicinity of the trees. It is well to 

 ridge the soil a little, directly about the trees, so that the 

 mice in burrowing beneath the snow will not be likely to 

 come in contact with the stems. Packing the snow im- 

 mediately about the trees is helpful when damage is dis- 

 covered during winter. The stems of orchard trees may 

 also be wrapped in heavy paper or inclosed in fine wire 

 netting. If tarred paper is used, it should be promptly 

 removed in spring, or it may injure the bark. 



