22 BULLETIN 614, U. S. DEPARTMENT OF AGRICULTURE. 
toward a vase shape with open head. In the better cared-for or- 
chards three to five leaders usually were chosen and headed back 
for the first 3 to 5 years, after which the pruning may be said to have 
consisted of merely the thinning out of the heavier lateral growth 
along the main limbs each year. When these trees reach the age of 
12 years they usually are severely headed back, and from then on 
are pruned in such a manner as to prevent them from reaching a 
size or shape which will inconvenience the operator in doing the 
principal orchard operations. In the older orchards comparatively 
little heavy wood is cut from the trees. ; 
Many factors affect the time required for this operation, chief 
among them being the variety, size, age, and number of trees per acre, 
as well as the expertness of the pruner. Perhaps the greatest of 
these factors is the pruner himself. His skill and ideals are told 
by each tree throughout the orchard. In considering these data no 
detailed study was made of the influence of these factors, the object 
being merely to obtain the average time required for the operation. 
There appears to be little difference in the cost of this operation in 
the two districts. (See Table XIV). The majority of farms and 
orchards do not vary greatly in size, so that the time required for 
the pruning is not affected greatly by the size factor. However, 
where the ranches are small a larger percentage of the acreage is in 
bearing apples and usually there is a greater number of trees per 
acre. In the Nob Hill section this is especially true, for the orchards 
occupy such a large percentage of the total acreages and there is 
usually so little other work to be done that the men spend more 
time on this operation than do the farmers of the Zillah district, 
because they do not feel the pressure of other work. 
Apparently there is little difference in the cost of pruning the 
trees under clean-cultural management as compared with those 
under mulch-crop management. There is, however, considerable 
variation in the number of trees which some men give as the average 
number which they are able to prune per day, the extremes being 
6 and 60. Considering the valley as a whole, it is found that a man 
will prune an average of 14 trees 12.6 years of age in a 10-hour day. 
The acre cost for pruning in the North Yakima district is $13.90; 
in the Zillah district it is $12.27. Considering the valley as a whole, 
the pruning cost is 19.5 per cent of the gross labor cost up to har- 
vesting time. The tree cost for this operation (18 cents) is the same 
in both districts. The difference in the acre cost is due to the fact 
that there are 78.2 trees per acre in Yakima and but 68.2 in Zillah. 
Taking the valley as a whole, with an average of 73.55 trees per acre 
having an average of 12.6 years, 52.55 man-hours are required to 
prune an acre, at a cost of $13.14, or 18 cents per tree. 
