394 SEEDING AND PLANTING 



often due to fungi entering wounds made in the trees at an 

 early age. In pruning operations every cut is a wound which 

 exposes the plant to disease that may later render the tree unfit 

 for use. 



The smaller the stock used in planting, usually the less the need 

 for pruning because of the less injury to the crown and root sys- 

 tem in the operations of lifting, transport, and planting. 



39. THE USE OF LAYERS 



A layer is a branch which is made to strike root while 

 still attached to and obtaining nourishment from the parent 

 plant. After the roots have developed, its connection with the 

 parent is severed and it is planted in the nursery or field in the 

 same manner as ordinary seedling or transplanted stock. The 

 tendency in plants to strike root from the stem cambium is quite 

 common, particularly in trees of warm regions. This method of 

 propagation has very little use in practical forestry but is more 

 useful in horticulture. The three kinds of layers from trees and 

 shrubs are: 



a. Layers from bent-over branches. 



6. Layers from stool shoots. 



c. Aerial layers. 



In the formation of layers from bent-over branches, the herbage 

 and litter is cleared from the ground at the proper point and the 

 ground loosened. The branch is bent downward to this point 

 and held in place with a forked peg driven into the ground and 

 covered to a depth of from 3 to 6 inches with rich earth. Some- 

 times a stem with numerous branches is bent down and covered 

 in similar manner, each of the branches as well as the main axis 

 later becoming rooted plants (Fig. 108). 



In making layers from stool shoots the parent plant is cut close 

 to the ground in early spring. By midsummer or as soon as the 

 stool shoots are well advanced a mound of rich earth is thrown up 

 around the stump and the base of the new shoots. The shoots 

 of some species produce abundant roots in the fresh soil and are 

 soon ready to be removed and set in the nursery or field. 



Where the stems or branches cannot be bent to the ground, 

 aerial layerings are sometimes made by encircling a portion of 

 the stem with soil surrounded with sphagnum moss kept con- 

 tinually moist. 



