GRAPES AND OTHER SMALL FRUITS 11 



browning. As seen from the outside, it appears merely as a darker 

 spot on the side of the berry. No investigation has been made of the 

 history of such injured places during the marketing process, but there 

 is little doubt that the skin over them is weakened and makes the fruit 

 more susceptible to attack by decay organisms (pi. 1, A). 



HEAT INJURY 



During periods of high temperature, especially those that come in 

 midsummer, grapes in California sometimes suffer serious damage 

 known as heat injury. In its commonest form this injury consists of 

 definite sunburn and even complete killing and drying up of part or 

 all of the fruit in bunches at the top of the vine or in places fully ex- 

 posed to the sun. 



In another form of heat injury frequently seen, the grapes become 

 wilted or softened, and the flabby wilted condition often remains per- 

 manent. In certain vineyards known to have suffered from high tem- 

 peratures, Malagas are sometimes found to be permanently collapsed 

 like a leaky rubber ball. These when cut show cavities in the pulp 

 around the seed. 



INTERNAL BROWNING 



In California, some grapes of the Malaga variety when seen from the 

 outside sometimes appear slightly darker than other berries in the bunch. 

 When cut, these are found to have a brownish discoloration hi the flesh 

 surrounding the seeds and extending to within about one-sixteenth of 

 an inch of the skin. In location and general appearance, the dis- 

 coloration is roughly analogous to that often found in apples affected 

 with internal browning. It does not seem to be due to decay organ- 

 isms and is not followed by decay. No other variety than the Malaga 

 has been found affected and nothing is known of the cause. 



OHANEZ SPOT 



The Ohanez variety of grapes (usually known to growers and re- 

 ceivers as Almeria) sometimes shows a spotting that does not occur 

 on any other variety except possibly Olivette de Vendemain. The 

 spots may occur at any place on the surface of the grape or in any part 

 of the flesh. Those on the surface are faint purple or gray and slightly 

 sunken; those in the flesh are brown and they sometimes underlie a 

 sunken area on the surface. Both kinds resemble drought injury in 

 plums and prunes and can be seen more distinctly if affected fruits 

 are held between the observer and a strong light. Under such con- 

 ditions or if observed in longitudinal sections, the spots are seen to be 

 associated with a brown discoloration of the vascular bundles (pi. 1, 

 B,C,D). 



The cause of the spots is not known. They are not associated with 

 decay of any sort, and there is no evidence that they increase in num- 

 ber or size in transit or storage. Nothing is known of methods of 

 control. 



POWDERY MILDEW 



(Uncinula necaior (Schw.) Burr.) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Powdery mildew occurs in practically all parts of the United States 

 where grapes are grown, but it appears on the market almost exclu- 



