.\sroM\vi. i ES 259 



necessary to continue such operations. To one familiar with tin- 

 life history of the fungus it is evident that: the time for spraying 

 will be governed by the condition in which the fungus is found. 

 \Yhen no spores are being produced spraying may be unneces- 

 sary ; when spores are being produced in quantity weekly spray- 

 ings may be demanded. Moreover, when it is necessary to spray 

 during the late season, ammoniacal copper carbonate may be sub- 

 stituted for the Bordeaux, in order to avoid the unattractive dis- 

 coloration of the fruit. 



XLI. CRANBERRY SCALD 

 Guignardia Vaccinii Shear 



SHEAR, C. L. Cranberry Diseases. Bur. Plant Ind., U. S. Dept. Agl. Built. 

 110: 1-64. pis. 1,2. 1907. 



Distribution and effects. Under the name of scald a number 

 of fungi affect the cranberry, but the most important diseases of 

 this plant are produced by the fungus above mentioned. It has 

 been estimated that the annual loss from cranberry scald is about 

 $200,000, and that this fungus is responsible for the greater part 

 of this amount. The disease is more common toward the south- 

 ern limit of cranberry culture, especially from New Jersey south- 

 ward, whereas further to the north, as in Massachusetts, it is far 

 less destructive. 



The fungus may attack very young fruit, and even flowers, 

 which promptly shrivel and die. The latter effect is commonly 

 known as " blast." Upon such parts the pycnidial stage of the 

 fungus is commonly found. The term scald is applied partic- 

 ularly to the effect upon the berry, which begins, according to 

 Shear, as a small watery spot upon the surface of young fruit. 

 This spot may remain small under certain conditions, and again 

 it spreads quickly, often concentrically, rendering the whole berry 

 soft, and sometimes marked by rings. This, however, is not a 

 definite character. There is little superficial evidence of the pres- 

 ence of the fungus, unless the berries are attacked before they are 

 half grown, when they may promptly shrivel and develop the 

 pyenidia of the fungus. The fungus also affects thT* leaves, and 

 when found upon these parts, brown spots, irregular in outline, 



