1893. J PUBLIC DOCmiENT — No. 33. 241 



3. The Cluster Cup or the Gooseberry (^cidium 

 Grossularice Schum.) occurred also on some of the leaves 

 sent by AV. C. Strong, Esq., as mentioned in the previous 

 note. Gooseberry leaves and berries very badly attacked 

 were also received, about the same time, through the " New 

 England Homestead," from Mr. C. C. Stickney of Ballard- 

 vale. From the facts which came to my notice during the 

 season, it would appear that this fungus has been more than 

 usually abundant this year. It may commonly be found in 

 early summer on gooseberry bushes, and occurs also on some 

 of our wild and cultivated species of currants (Ribes) ; but it 

 is rarely very destructive. It may, however, as was seen this 

 year, assume serious proportions, practically destroying a 

 large part of foliage and fruit. It seems not to have 

 attracted much attention as a cause of loss, but has lately 

 been said by Pammel* to be quite destructive in Iowa. The 

 form we are considering is the " cluster-cup" stage of one 

 of the rust fungi. The bright yellow cups occur in groups 

 on somewhat swollen and discolored portions of the leaves 

 or berries, and contain the chains of spores by which the 

 further development of the species is accomplished. It is 

 probable that, as in other rusts, this "cluster cup" is 

 followed bv red-rust and black-rust forms. But, as these 

 are not known to be developed on the same host-plant, they 

 are probably produced on a second one. This would place 

 the present fungus among the heteroecious rusts. So long, 

 however, as we do not know its life history, we cannot avail 

 ourselves of all the means of combatinof it. 



When the cluster cup begins to appear, in spring or early 

 summer, the harm for that season is done, and cannot be 

 avoided. Yet, if the discolored spots be watched for and 

 the affected parts picked and burned before the cups have 

 burst open and discharged their &pore, one may hope to 

 escai)e attack in a considerable measure the following year ; 

 and the annual repetition of this practice should result in 

 comparative immunity from the fungus. This recommenda- 

 tion is based on the justifiable assumption that the cluster- 

 cup form requires for its reappearance the development of 



* Journal of Mycology, VII., p. 101, 1892. 



