40 CIRCULAR 2 78, U. S. DEPARTMENT OF AGRICULTURE 



potatoes do not have to be moved after the curing treatment. When 

 commercial lots are handled, the storage house is generally of special 

 construction with sufficient insulation to maintain a uniform tem- 

 perature and some means of ventilation that will insure the desired 

 humidity. Provision should be made for heating the building during 

 the curing process and for holding the proper storage temperature 

 afterward. The curing process ordinarily takes fom 10 to 14 days, 

 during which the house is kept at a temperature of 80° to 85° F., with 

 a relative humidity of 85 to 90 percent. After the curing period the 

 storage temperature is allowed to drop to about 55°, with a humidity 

 of 75 to 80 percent. Short periods of a few hours at temperatures 

 somewhat lower than 50° need not cause alarm, but prolonged periods 

 of low temperature should be avoided because of the danger from cer- 

 tain types of decay, which are more likely to develop at temperatures 

 below the range given (37, 82). Under the recommended conditions, 

 properly cured stock should keep satisfactorily for 4 to 6 months. 



Only well-matured stock that is practically free from mechanical 

 injury or decay should be used for storage. Sweetpotatoes are usu- 

 ally stored in slat crates of about a bushel capacity or in bushel 

 baskets. Shallow bins are sometimes used. The roots should be 

 handled as little as possible during storage. 



Tomatoes 



(Temperature: ripe, 40° to 50° P.; mature green, 55° to 70° ; relative humidity, 85 to 90 



percent) 



Ripe tomatoes are held in storage only temporarily and, except for 

 short storage, should not be stored at temperatures lower than 40° F. 

 At 40° to 50°, if not already soft ripe, they will keep in good condi- 

 tion for a week to 10 da}^s ; at temperatures lower than this they some- 

 times show a tendency to break down. 



Green tomatoes are best kept at a temperature not lower than 55° F. 

 At this temperature ripening progresses slowly but satisf actorily, and 

 mature green tomatoes can be kept for 3 to 5 weeks before becoming 

 overripe. At temperatures much below 55° green tomatoes do not 

 ripen well and if kept there more than about 8 days and then moved 

 to a warmer place usually do not ripen satisfactorily; on the other 

 hand, if they are to be kept for less than 8 days they can be held at 

 40° or even somewhat lower. If fairly rapid ripening is desired, 

 temperatures from 60° to 70° should be used. At 70° or slightly 

 above, ripening is accelerated, but so also is the development of decay, 

 which will be found difficult to control. At about 80° coloring will 

 be uneven since the development of the red pigment is inhibited at 

 this temperature or above. The relative humidity of tomato-storage 

 or tomato-ripening rooms should be from 80 to 85 percent. 



(See 88, 103, 105.) 



Turnips 



(Temperature, 32° F. ; relative humidity, 95 to 98 percent) 



Turnips require the same storage conditions as carrots. They can 

 be expected to keep for 4 to 5 months. 



Frozen Vegetables 

 For treatment of frozen vegetables see page 25. 



