88 CRANBEKRY DISEASES. 



complete destruction of the vines was threatened. So far as known 

 the only measure taken to prevent the disease was the withholding 

 of the water during the winter, as it was believed that the disease was 

 distributed chiefly by the water. This plan seems to have proved 

 successful, as the disease disappeared entirely within a few years. 

 When the affected bog was recently visited it was impossible to find 

 a trace of the fungus present on the vines or to learn of its occurrence 

 anywhere in the region since. It seems to have entirely disappeared." 

 Similar sudden appearances of new parasites have been observed. Xo 

 entirely satisfactory explanation of such phenomena has yet been 

 given. Their sudden disappearance is less common. This fungus is 

 not restricted to the cranberry plant, but has been found on several 

 other ericaceous plants. Specimens on the following hosts collected hj 

 Doctor Halsted in New Jersey are preserved in the pathological col- 

 lections of the Department : Gaultheria procumhens^ Cassandra caly- 

 culata, Kalmia angiistifolia, Azalea viscosa, Clethra alnifoUa, and 

 Gaylussacia sp. It may be expected to appear again if the condi- 

 tions for its development and spread should happen to be favorable. 

 Since its discovery in New Jersey it has been found as far north as 

 Newfoundland, but has not been reported as doing harm to the cran- 

 berry, except in the case mentioned. 



Pestalozzia guepini vaccinii Shear.-- — This fungus has been 

 isolated in eight instances from diseased cranberries. It is also 

 frequently found on the leaves of the cranberry plant. The effect of 

 this fungus upon the berries, like that of some other parasites, is not 

 sufficiently characteristic to enable one to recognize it by an examina- 

 tion of the fruit. Hence we are unable to determine how much injury 

 is caused by it. The indications are, however, that it does not do 

 nearly as much damage as the other parasites already described. It 

 is much more frequent upon the leaves than upon the berries and 

 may be found upon the recently fallen leaves during the summer. It 

 also develops very frequently on leaves apparently free from disease 

 Avhen they are placed in a sterile moist chamber. 



The acervuli of the fungus are formed beneath the epidermis and 

 are sparsely scattered over the leaf (PI. II, fig. 15). As the fungus 

 matures the epidermis ruptures and the spores collect in dark masses 

 or spread out and form a thin layer upon the surface about the 

 acervuli. The conidia are elliptical and somewhat inequilateral and 

 usually four-septate (PI. II, fig. 15, «, 6). The three central cells are 

 dark colored and usually guttulate. The septum below the upper cell 

 is usually darker than the others. The two terminal cells are hyaline, 

 and the apical one is furnished with tJiree to four filiform seta% 



o Since this was written the disease has again been reported as occurring this 

 season in New Jersey. 



110 



