16 CIRCULAR 2 7 8, U. S. DEPARTMENT OF AGRICULTURE 



with, stem-end rot, blue mold and green mold rots are relatively less 

 important in storage on Florida and Texas grapefruit. Stem-end rot 

 is not known to occur on California fruit (5, 12, Jj.2, 43, 55, 56, 57). 



GRAPES 



VIXIFERA 

 (Temperature, 31° to 32° F.; relative humidity, 85 to 90 percent") 



Large quantities of the European or vinifera grapes, grown princi- 

 pally in California, are stored every year. The most important of the 

 varieties stored are Emperor and Ohanez (Almeria). Olivette de 

 Vendemain, Malaga, Sultanina (Thompson Seedless), Cornichon, and 

 Ribier are also occasionally stored. All of these have low freezing 

 points, lower in fact than that of any other important fruit, largely 

 because of their high sugar content. Although for most varieties 

 there is no danger of freezing injury at temperatures as low as 28° F. 

 (8), they are usually held at temperatures of 31° to 32°. At low air 

 velocities a humidity of So percent prevents excessive wilting of stems 

 and berries without favoring the formation of mold growth. At air 

 velocities of 100 to 150 feet per minute a humidity of 90 percent is 

 desirable (32). 



California grapes for cold storage are packed in kegs or drums in 

 sawdust or in various types of lidded lugs with or without sawdust. 

 Good results are usually obtained, although if the fruit or the sawdust 

 is damp at packing time or becomes so in storage there is danger of 

 damage by mold. Mold may develop also if the grapes have been 

 handled carelessly and if there are numerous cracked or loosened ber- 

 ries scattered through the pack. Varieties differ in keeping quality. 

 The best storage varieties, packed in sawdust, can be held 2 to 4 

 months at 32° F. Emperor and Ohanez seem to keep better than any 

 of the other storage varieties. Treating grapes with sulphur dioxide 

 before placing them in storage has been found helpful in preventing 

 decay. Sodium acid sulphite placed in the sawdust, in sawdust lugs or 

 kegs, or in the pads at the top and bottom of display lugs releases 

 sulphur dioxide over a long period and has given good control of decay 

 without causing fruit injury, if not used in a too-strong concentration. 

 The most effective, safe concentration of the sulphite is 5 to 10 grams 

 per lug or keg {31). 



Storage quality varies considerably from season to season and 

 seems to be adversely affected by ram just before and during harvest. 

 Grapes picked before rains usually keep better than those picked after 

 rains. 



AMERICAN 



(Temperature, 31° to 32° F.; relative humidity, 80 to So percent) 



The eastern or American varieties of grapes, the most important of 

 which is Concord, are not adapted to long storage and most of them 

 do not hold up well under storage conditions for more than 3 or 4 

 weeks. After that time they begin to deteriorate in flavor and may 

 suffer heavily from decay if the temperature is not kept close to 

 32° F. The Catawba keeps better than most other eastern varieties 

 and, if in good condition when stored, can be held for 3 to 4 months 

 even in common storage in the districts where this variety is grown on 

 a commercial scale. 



