494 INSECTS AFFECTING VEGETATION 



what are popularly called, among growers, cranberry blast, cran- 

 berry scald, the cranberry rot, and anthracnose. Cranberry blast 

 and scald are really but different effects produced by the same par- 

 asitic fungus. 



Cranberry Blast, Cranberry blast is a name given to that 

 form of the disease which attacks the very young fruits as soon as 

 the blossoms fall. It causes the fruit to shrivel up, become black, 

 and finally become covered with one of the spore-producing forms 

 of the fungus, which is a species of Guignardia, very closely related 

 to the species which produces the black-rot of the grape. The 

 spores produced upon the young berries are the probable source of 

 infection of most of the other fruit. This fungus, which is repre- 

 sented in its various forms, produces two kinds of fruit, or, in other 

 words, passes through two stages of development. The earliest stage, 

 called the pycnidial form, produces its spores in small black spherical 

 receptacles. The spores are furnished with an appendage at the end. 

 This fruiting form of the fungus is the most abundant, and it is 

 probably from this source that most of the leaves and fruits are in- 

 fected. The second stage in the development of the fungus is that in 

 which the spores are produced in sacs. These are inclosed in recep- 

 tacles (perithecia), as in the other stage mentioned. 



Cranberry Scald. The name scald originated as a result of 

 the belief formerly prevalent among cranberry growers that the 

 injury was due to the effect of the hot sun upon the berries when 

 they were wet, thus producing what was regarded as a real scald- 

 ing of the tissues of the fruit. Fruit which has been overflowed for 

 a half day or more during hot weather may be injured as a result, 

 and the effect in many instances closely resembles that produced 

 by the scald fungus. A microscopic examination of the berries 

 shows at once the difference. In the berry which has been affected 

 by being covered with water no fungous threads or filaments can 

 be found, whereas in the case of the berry attacked by the scald 

 fungus an abundance of such filaments may readily be observed 

 in the pulp of the diseased berry. Only in the rarest instances does 

 the scald fungus fruit on the berries after they have become half 

 grown. 



The disease first becomes noticeable as a small light-colored 

 softened spot on the surface of the berry. This spot rapidly in- 

 creases in circumference and finally envelops the whole fruit. 

 Sometimes the diseased portion shows more or less distinct brown- 

 ish zones. In other cases the zones are lacking and the whole 

 fruit becomes very soft and has a light watery color. In many 

 instances it is very difficult to tell from the external appearance 

 only whether the disease is due to the scald fungus or the rot 

 fungus. 



Cranberry Rot. Cranberry rot has until recently been con- 

 fused with and attributed to the same cause as the scald. Its effect 

 upon the berry is very similar to that of the scald fungus. It is 

 produced, however, by a quite different species of parasite, though 

 belonging to the same large group known as the black fungi. In 



