WHITE-PINE BLISTER RUST. # 



The disease had evidently reached a stage at this place where its 

 future spread would be much more rapid than it has been in the past. 

 About lOOfeetfrom the apparent original center of infection was a single 

 black-currant bush (Ribes nigrum), 1 some 50 to 75 red-currant bushes 

 (Ribes vulgare) , and about 30 gooseberry bushes (Ribes grossularia) . 

 The leaves of the black currant were covered with telia and uredinia 

 of Cronartium ribicola, but only a very few sori were found on the 

 red currants and none on the gooseberry leaves. Evidently the 

 conditions have been extremely favorable for the propagation and 

 spread of the fungus ever since the Ribes were set in that locality. 

 All of the Ribes have been removed and destroyed, and the diseased 

 trees and parts of trees are being cut out and destroyed. 



Late in the fall of 1912 the writer received a specimen of blister 

 rust on leaves of Ribes from Ipswich, Mass. In the spring of 1913 

 two small white pines which bore fruiting bodies of the fungus were 

 found by the State nursery inspector near the diseased Ribes bushes. 

 These were destroyed, and it was believed that the disease had been 

 eradicated. It appeared later, however, about half a mile away, on 

 leaves of Ribes nigrum and of Ribes vulgare of the variety Red Cross. 

 The abundance of the fungus led the writer to suspect the center of 

 infection to be near by. An examination promptly revealed evidences 

 of the disease on neighboring white pines of about 10 and 18 years of 

 age. Steps are being taken to remove the diseased trees and branches 

 and also the black currants. 



In 1913 Clinton 2 reported an outbreak of this fungus on the leaves 

 of black currants near Meriden, Conn., late in 1912. He examined 

 the vicinity, but could find no infected white pines in that locality. 

 The origin of this outbreak is still unknown, and for this reason the 

 situation is perhaps more dangerous than that in any other locality 

 where the disease is now known to occur. 



SERIOUSNESS OF THE DISEASE. 



In the Vermont locality mentioned one large white pine about 2 

 feet in diameter and quite mature from the lumberman's standpoint 

 was found to have the disease scattered throughout the top. 

 Branches of all sizes up to 4 inches in diameter were thus affected. 

 From the condition of this tree it was very easy to understand how a 

 large tree may be killed by very severe attacks of this fungus, since 

 it is a mere matter of time before an attacked branch or tree trunk is 

 killed above the point of infection. One tree about 20 years of age, 

 which had been infected in the trunk about 10 feet from the ground, 



i The three Ribes mentioned are cultivated species which have been introduced into this country from 

 Europe. The last (Ribes grossularia) is usually placed in a different subgenus than are the two first; by 

 some authors it is placed in a separate genus. 



« Clinton, G. P. Notes on plant diseases of Connecticut. In Conn. Agr. Exp. Sta. Rpt., 1912, p. 347-348. 

 1913. 



