10 BULLETIN 50, HAWAII EXPERIMENT STATION. 
the transaction and sweet potatoes are marketed practically free 
fro:n cuts, bruises, decay, scars, cracks, and other defects resulting 
from carele'ss handling, as well as from diseases and insect pests. 
SELECTION OF SWEET POTATOES FOR HOME USE. 
Fully 15 to 25 per cent of the total weight, depending upon the 
shape of the roots, is lost in the paring of sweet potatoes which are 
intended for culinary use. In other words, there is removed in the 
form of paring from H to 2\ pounds by weight for every 10 pounds 
of sweet potatoes pared. For this reason there should be selected 
for home use regular-shaped, uniform, smooth, firm, and fresh- 
looking roots rather than shriveled or irregular-shaped specimens. 
STORING. 
In Hawaii the sweet potato is not stored for future use for any 
great length of time, because the crop can be harvested during any 
month of the year. After sunning for a few hours in the field the 
roots are taken to a shed and spread out in shallow piles to cure 
thoroughly. A number of sweet-potato growers on Oahu make it a 
practice to harvest just enough to supply the current needs of the 
wholesaler, and the native Hawaiians never harvest more than the 
actual quantity of roots needed to supply the household for the day. 
In this they show an appreciation of the quality of the freshly dug 
root and a knowledge of how to eliminate the problem of storage. 
The small gardener would do well to adopt their practice. 
SHRINKAGE IN STORAGE. 
Data obtained at the experiment station on shrinkage occurriDg 
in sweet potatoes, which are sacked and left in a cool but dry room, 
show that a loss of 12 per cent of the original total weight takes 
place in 21 days, approximately 6 per cent of which is lost during the 
seven days immediately following harvesting and 6 per cent during 
the next 14 days. It is evident, therefore, that sweet potatoes should 
be carefully stored to reduce the loss by shrinkage to a minimum. 
Storage houses intended for sweet potatoes should have wooden 
roofing, which does not have the same heat-retaining properties as 
does galvanized-iron roofing, and the storage rooms should be kept 
cool and dark. 
COST OF PRODUCTION. 
The cost of producing a crop of sweet potatoes depends largely upon 
the locality where it is grown and the method of growing. On level 
land, where labor-saving devices can be used to do considerable of 
the work, the cost per acre is less than is the case on hilly lands where 
the greater part of the work has to be done by manual labor. In 
Hawaii, where labor is rated as an expensive item, the cost of pro- 
ducing an acre of sweet potatoes ranges between $80 and SI 00, 
exclusive of the charge for rental of land, fertilizers, and cost of 
sacks. The following table gives the comparative cost of producing 
sweet potatoes at the central station, the substation at Haiku, and 
on the mainland: 
