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



fruit in storage. Stem-end rot is not known to occur on California 

 and Arizona grapefruit. 



(See 10, &h 92, 93, H, 111, 112, 113.) 



Grapes 



vinifera 



(Temperature, 30° to 31° 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 

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

 Alphonse Lavallee (Ribier) are also occasional^ stored. All of these 

 have low freezing points, lower in fact than the freezing point 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. (13), they are usually held at tempera- 

 tures of 30° to 31°. At low air velocities a humidity of 85 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 (2,67). 



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 when properly handled can be held 3 to 6 

 months in storage at 30° to 31° F. Emperor, Ohanez, and Alphonse 

 Lavallee (Ribier) seem to keep better than any of the other storage 

 varieties. Treating grapes with sulfur dioxide has helped to reduce 

 spoilage in storage. In recent years the display type of lug has 

 grown in favor for storage, because grapes packed in it can be re- 

 fumigated. The common practice is to fumigate with concentrations 

 of about 1 percent of sulfur dioxide before storage and to refumigate 

 with about 0.2 percent of the gas at intervals of 10 days. Under these 

 conditions fruit has been held fully as long in this type of package as 

 in the more expensive sawdust chests or kegs. When fruit packed in 

 display lugs cannot be refumigated in storage, 5 grams of sodium 

 bisulfite is often added to the pads before packing, and this is fol- 

 lowed by the usual prestorage fumigation. Mixing 5 grams of 

 sodium bisulfite (per lug, chest, or keg) with the sawdust used in 

 packing grapes has also been effective in checking decay (66). 



Storage quality varies considerably from season to season and 

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

 Grapes picked before rains usually keep better than those picked after 

 rains. 



(See 13, 65.) 



