106 MISC. PUBLICATION 4 3 4, U. S. DEPARTMENT OF AGRICULTURE 



A sharp blade with a lifter attachment is essential, although in loose 

 soils the lifter may be removed. Tractor power has proved to be 

 more satisfactory for pulling diggers than animal power. Generally 

 an ample and more uniform pull is assured without the inconvenience 

 and delay caused by frequent resting of the horses or mules. (Fig. 37.) 

 The digger should be set to run at a uniform depth of approximately 

 11 inches, since this root length has been found convenient and of 



Figure 37. — U-blade tree digger mounted on tool bar of tractor. Depth of 

 undercutting is gaged by adjustment of levers on tractor. Blade is raised or 

 lowered by power lift. Blade is constructed of %&- by 6-inch plow steel, rein- 

 forced at top where fastened to cultivator shank. Blade is 28 inches deep 

 and inside width above bottom curvature is 10 inches. Rear bolt hole is 1 

 inch lower than front, thus giving blade necessary tilt. 



adequate length for plains planting. If the lifter is set for a greater 

 depth, additional pruning of the longer roots will be necessary. A 

 clean sharp cut at time of digging will permit the cut ends of the root 

 to heal up properly in the heel-in bed. Following the undercutting 

 operations, the seedlings are pulled, long lateral roots are cut to 

 convenient planting size, and the trees are graded, counted, and tied 

 in bundles. 



Grading Technique 



Grading the stock in the field and selecting only the usable seed- 

 lings greatly simplifies and speeds up the entire operation and dis- 

 penses with double handling of the stock. The usual commercial 

 practice in the plains region is to place the seedlings in a storage 

 building immediately after pulling, and to perform all subsequent 

 operations under cover when time is available, with a few specially 

 trained men. Since commercial practice demands that the seedlings 



