GRAPES AND OTHER SMALL FRUITS 7 



BRUISING 



Bruising injury occurs on grapes that are in contact with the lug 

 or other container during a storage or transit period. It appears as 

 flattened areas that vary in size according to the severity of rubbing or 

 pressure to which the berries have been subjected (pi. 5, A). The 

 affected areas sometimes show no discoloration, but on light-skinned 

 fruit they are usually brown and on dark-skinned fruit they may be 

 dark brown or black. 



If the bruising is severe it is to that extent a factor predisposing the 

 fruit to decay under favorable temperature conditions. 



BUCKSKIN 



Buckskin of grapes is a slight roughening or dulling of the skin, 

 usually on the side of the bunch most exposed to the direct rays of the 

 sun. It does not seem to grade into the condition known as sun 

 kissed, but there is a possibility that the two are merely different 

 manifestations of injury by heat and light. 



Buckskin is more common on the Flame Tokay than on other 

 varieties. So far as known it has no effect on the shipping or storage 

 quality of the fruit. It is not known to occur on eastern grapes. 



CRACKING 



Grapes of the Flame Tokay, Mission, Petit Bouschet, Syrah (Petite 

 Syrah), Bibier, 5 Castiza (Red Malaga), and Cornichon varieties some- 

 times show cracking at the blossom end or on the side. The cracks 

 are rarely more than one-fourth of an inch long and one-eighth of an 

 inch deep. In time the edges of the broken skin become dry and curl 

 inward. Infection with various decay organisms frequently occurs, 

 especially in storage. That caused by gray mold is the most serious, 

 works the most rapidly, and not only destroys the grape in which 

 infection originally occurred but spreads to others around it. Less 

 common is infection by an olive-green mold (Cladosporium sp.) which 

 appears in dry, hard pockets one-eighth to one-fourth of an inch deep, 

 but does not seem to be at all active in causing decay (pi. 5, G, H, I). 



Of the susceptible varieties named above, the Flame Tokay, Castiza 

 (Red Malaga), and Ribier 5 suffer most. Nothing is known of the 

 cause of the cracking on these or any of the other varieties. Cracking 

 of eastern grapes (American varieties) seems to be associated with wet 

 weather late in the summer, and there is some evidence that it can 

 be reduced in amount bv late cultivation (22). 



DOWNY MILDEW 



(Plasmopara viticola (Berk, and Curt.) Berl. and De Toni) 



Downy mildew attacks all the tender growing parts of the vine, 

 and in humid sections of the country it sometimes causes more loss 

 than black rot. On young fruits it appears first as brownish spots 

 that later become covered with the gray downy growth of the fungus. 

 This stage of the disease is sometimes called gray rot. On older 

 fruits the disease occurs at separate points as brown or brownish- 

 purple patches; the skin becomes withered and eventually the whole 



6 Alphonse Lavalee is the accredited name, but the variety is grown commercially in California under 

 the name of Ribier. 



