GRAPES AND OTHER SMALL FRUITS 19 



STRAWBERRIES 



GRAY MOLD ROT 



(Botrytis sp.) 



Gray mold rot is one of the most serious diseases of strawberries 

 and sometimes occurs on raspberries, blackberries, and dewberries. 

 The disease is caused by a species of Botrytis apparently identical 

 with the one that attacks grapes (pi. 9, A, G). The characteristics of 

 that fungus and its relation to temperature and moisture conditions 

 are given under Gray Mold Rot of Grapes (p. 8). 



Blackberries, raspberries, and dewberries attacked by the fungus 

 are soft and watery, whereas affected strawberries are firm and fairly 

 dry superficially since in them there is no marked collapse of the 

 tissues and little or no leakage of juice. 



On strawberries, gray mold rot is most common in the cooler 

 producing regions, where it sometimes causes a loss of 10 percent or 

 more of the crop in the field. As noted under Grapes, it is especially 

 favored by wet weather. In such weather the rot is worse in places 

 where the leaf cover is heavy and conditions are particularly favorable 

 for the growth of the fungus on flowers, flower stalks, fruitstalks, and 

 various kinds of debris on the soil as well as on the fruit. 



Raspberries, blackberries, and dewberries suffer very little from 

 gray mold rot in the field apparently because they are borne singly 

 or in small open clusters and not close to or on the ground like 

 strawberries. 



Gray mold rot attacks strawberries and other berries in transit and 

 on the market, its development there depending on favorable condi- 

 tions of moisture and temperature (p. 10). If berries affected with 

 rot are allowed to remain in the packed fruit, they become centers of 

 infection around which nests of rot may develop, as described for 

 grapes (p. 8). 



Probably very little can be done to control the rot in the field if 

 conditions there favor its development. Control in transit depends on 

 careful handling of the fruit to avoid bruises and skin breaks, careful 

 culling wherever practicable to remove decaying fruits, and a temper- 

 ature below 45° F., preferably about 40°. The culling is most effective 

 when done in the field, because this practice avoids much of the bruis- 

 ing likely to occur if the culling is done in the packing shed. 



Development of gray mold rot and other rots on the market can 

 best be prevented by moving the fruit into consumption as quickly 

 as possible (8, 11, 14, 29, 31, 33, 36, 37, 38, 39, 40, 43, 46, 50). 



LEATHER ROT 



(Phytophthora cactorum (Leb. and Cohn) Schrt.) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Leather rot is a fungus disease of strawberries that has been found 

 in the field in Mississippi, Louisiana, Arkansas, Tennessee, Virginia, 

 Maryland, Missouri, Illinois, and Kentucky and on the market in 

 carlot shipments of strawberries from these States. It is most de- 

 structive in the Klondike and Aroma varieties. 



Leather rot is characterized by a rather slight softening of affected 

 tissues, by both external and internal discoloration, and by a marked 



