Gooseberry Cluster-cup 353 



there produced cannot infect other pines. Hence the disease cannot 

 spread directly from pine to pine. It must first go to the groselles 

 and from there back to pine. Various species of currants and goose- 

 berries are subject to attack. Certain spores produced by the fungus 

 while living on them can only infect the pine. Those of another 

 type affect groselles readily, so that during summer and autumn 

 the disease may spread readily among these plants. Only the leaves 

 of these plants are attacked, so that the work of the fungus ends 

 with the season, so far as they are concerned. Difficulty in explain- 

 ing certain outbreaks of the disease have led to the suggestion that 

 perhaps in some form the fungus may pass the whiter on Ribes 

 plants. Careful experiments have shown, however, that rarely if 

 ever does such a thing occur, and then certainly not under normal 

 conditions. 



Control. This rust is a European disease, and is found chiefly on 

 imported pines. Since it is only from such sources that it can spread, 

 care should be taken to prevent the dissemination of such stock or its 

 being allowed to remain if found. The fungus is a more serious 

 enemy to the pine than to the groselles. In Europe it has driven 

 the growing of white pine out of some nurseries and localities. It 

 has been urged that the importation of five-leaved pine should be 

 stopped and that they should be kept away from groselles in the 

 nursery. If the disease is found it is recommended to destroy the 

 least valuable group entirely and all diseased plants in the other. 



Just at the present time this disease appears to be causing great 

 consternation in the United States. Several states have estab- 

 lished quarantine regulations forbidding the importation of five- 

 leaved pines and of currants and gooseberries within their borders. 

 References. 



Geneva, N. Y., Expt. Sta. Bull. 374 and Tech. Bull. 2. 



Bur. of Plant Indus. Bull. 206. 



GOOSEBERRY CLUSTER-CUP 



Puccinia ribis-caricis, Kleb. 



This disease takes the form of reddish-yellow swellings on the 

 leaves and fruit with clusters of minute cups imbedded in the dis- 



