44 BULLETIN 479, U. S. DEPARTMENT OF AGRICULTURE. 



spruce thrives much better if shaded during the second year at the 

 Boulder, Savenac and Monument Nurseries. The same is true with 

 bigtree at the Savenac, Douglas fir at the Pocatello, and western red 

 cedar (Thuja plicata) and Norway spruce at the Wind River 

 Nursery. At the Converse Flats Nursery 2-0 Jeffrey pine and 2-0 

 incense cedar are shaded, but it is not known to be necessary. At the 

 Page Creek Nursery the shading of sugar pine in its second year in 

 the seed beds has proved undesirable, because the seedlings when 

 shaded reach a size larger than is convenient for transplanting. 



BOOT PRUNING. 



Root pruning is the cutting off of the lower part of the roots of 

 seedlings without removing them from the beds. Its object is to 

 promote the growth of lateral finely branched roots and a stocky 

 top (Pis. IX and X). It is especially worthy of trial for species 

 with very pronounced taproots or with any species when field plant- 

 ing is to be attempted with seedling stock. It is a practicable opera- 

 tion only when the seedlings are grown in drills or in narrow broad- 

 casted strips. It has not been tried extensively at Forest Service 

 nurseries, and the results of the practice are not yet conclusive. 



One type of pruner that has been used is a large butcher knife, 

 which is thrust into the ground between the rows at an angle of 

 about 45° and then drawn along so that its edge severs the roots 

 about 6 inches below 7 the surface of the soil. Another is a heavier 

 blade about 12 inches long which is bent below the middle and has 

 its lower cutting end slanted somewhat downward. It has two han- 

 dles at right angles to each other and about 8 inches apart. Before 

 starting to prune with this tool the soil between two rows of trees is 

 cut with a spade, then the bent end of the pruning blade is dipped 

 into the soil at the end of a row and drawn along as in shaving at 

 any desired depth under the surface. The tool most commonly used 

 is a sharp spade, which is driven into the soil at an angle along one 

 or both sides of a row of seedlings and thus cuts off a portion of the 

 roots. The advantage of using a spade is that it can be operated 

 more rapidly than the other tools and can be used even in stony soils. 

 The other tools are not very efficient under any condition, and are 

 especially impractical in stony ground because they are quickly 

 dulled. In Australia root pruning with spades is practiced even 

 where broadcast sowing is done in long strips 12 to 13 inches wide. 

 Two men with sharp spades work together. Facing each other on 

 opposite sides of a strip, each thrusts a spade into the soil on his side 

 of the row, guiding it at an angle of about 45° downward and toward 

 the center of the strip. The spades meet, practically insuring Ik*' 

 severance of the lower portions of the roots of all seedlings in the 

 strip. 



