i8o Diseases of Truck Crops 



clear understanding of the storage problem. Investi- 

 gations have shown definitely that the greatest loss 

 from disease in storage is due to soft rot. It has been 

 estimated that 90% of the loss is due to this one 

 disease, 9% to black rot, and i% to all other rots. 



Table 14 gives part of the data collected in Novem- 

 ber, 1909, at the storage house of Huston Darbee, 

 Seaford, Del. The thermometer readings are re- 

 corded in Fahrenheit degrees and the compara- 

 tive moisture readings are taken with Mitthof's 

 hygrometers. Whenever the readings of the hy- 

 grometer run over 70 and remain there for some 

 time, soft rot sooner or later sets in. 



Table 14 also shows that not only is the tempera- 

 ture different in the different parts of the same floor, 

 but that it differs on different floors. Any ventila- 

 tion which will bring down the moisture content ten or 

 twelve per cent, will help keep sweet potatoes. How- 

 ever, natural ventilation will not always accomplish 

 this, since the moisture content of the outside air is 

 the great governing factor. For instance, it is seen 

 in Table 14 that from the ist to the 5th of November, 

 1913, the weather was fair and the air dry; hence by 

 opening up doors and windows in the morning, the 

 moisture readings were greatly reduced. However, 

 on the 7th, the moisture increased when the ventila- 

 tors were opened on the first floor. A fair day, there- 

 fore, does not always indicate dry air, just as a cloudy 

 day does not always mean moist air, as is indicated 

 by the hygrometer readings on both floors during the 

 1 4th of November. Rainy days and damp weather 



