GEAPES AND OTHER SMALL EEUITS 23 



greater when they are many. Grapes which have been handled so 

 carelessly that many of the individual fruits are cracked or even no 

 more than loosened on the cap stem, and strawberries and other berries 

 that have been bruised by careless picking or by being packed too high 

 in the containers are much more susceptible to attack by Rhizopus 

 than are fruits that have been carefully handled at all times. 



CONTROL MEASURES 



The danger of attack in transit by Rhizopus, therefore, is greatly 

 increased by the presence of skin breaks and moisture; whether or 

 not the attack takes place depends almost entirely on the temperature 

 at which the fruit is held. For the species of Rhizopus (R. nigricans) 

 which is most common in transit and on the market, the critical temp- 

 erature or danger point is about 50° F.; 2° or 3° above this gives a 

 chance for decay to begin; 2° or 3° below, the product is fairly safe. 

 Delay in cooling, due either to failure to ice cars promptly or to load- 

 ing of warm fruit, gives opportunity for the rot to develop and so 

 increases the liability of loss; delay in moving the car also increases 

 this probability, for by giving the fungus a longer time in which to 

 work, it aggravates a condition that already exists, or causes one to 

 arise tha-t would not have done so had the car moved on time. For 

 such perishable fruits as strawberries and other berries the importance 

 of precooling immediately after the completion of loading into refriger- 

 ator cars is beyond question (8, 11, 14, 16, 17, 18, 29, 31, 32, 33, 36, 

 37, 38, 39, 40, 42, 45, 50). 



SCLEROTINIA ROT 



{Sclerotinia sp., probably S. libertiana Fckl.) 



Strawberries affected with sclerotinia rot are firm but rather watery 

 and usually show small patches of a white, cottony, fungus growth 

 that becomes quite luxuriant if the berries are held in a close moist 

 place. If held in a dry place, the berries shrivel and the fungus 

 growth collapses and finally develops hard, rounded black masses 

 known as sclerotia or resting bodies. 



The disease occurs in various sections of the South but is not often 

 seen on the market. Losses caused by it are probably not large. 



TAN BROWN ROT 



(Pezizella lythri (Desm.) Shear and Dodge) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Tan brown rot has been found in Cuba, Louisiana, Florida, 

 Arkansas, Tennessee, Virginia, Maryland, Wisconsin, and Alaska. 

 When field and transit conditions have been favorable for its develop- 

 ment it also appears, sometimes in rather high percentage, on fruit 

 shipped to the market. 



The rot occurs on both green and ripe fruit as sunken, softened, tan- 

 colored spots (pi. 8, F), which extend more deeply into the flesh of the 

 berry than might be suspected from their superficial diameter. The 

 rotted tissues are so thoroughly interpenetrated and held together by 

 the fungus as to form a core that can easily be removed intact. The 

 spots vary in diameter from about one-fourth to one-half inch, but 



