CULTIVATED BLACK CURRANTS 

 ENDANGER WHITE PINES 



It has been determined that the Enro]3ean or cultivated black currant is 

 the most susceptible host plant of the white pine blister rust. The blister 

 rust is a disease caused by a fungus which spends a part of its life growing 

 in the leaves of currant and gooseberry plants, and the remainder, in the bark 

 of white pine trees. The disease is only slightly injurious to currants and 

 gooseberries, but kills white pines of all sizes. The rust spreads by means 

 of wind-carried spores (like seeds). These disease spores can not spread 

 the rust to white pines, unless currant or gooseberry bushes are present. 

 All kinds of currants and goosel)erries are attacked, but the cultivated black 

 currant becomes diseased more easily than other kinds, and is more active in 

 spreading the rust. 



COMPARATIVE IMPORTANCE OF WHITE 

 PINES AND BLACK CURRANTS 



The white pine is the most valuable timber tree in ^Massachusetts, and ranks 

 high in the development of forestry within the State. There are thousands 

 of acres of young pine growth in Massachusetts, which, if protected from the 

 blister rust, will provide the white pine lumber of the future. The wood 

 of white pine, in one form or another, is used for so many purposes that the 

 preservation of our white pine forests is of importance, not only to pine 

 owners, but indirectlv to every citizen. 



On the other hand, black currants are not grown in large numbers in 

 Massachusetts, and are of very little commercial value. The black currant 

 is not a native American plant; it is of European origin. The blister rust 

 likewise came to us from Europe. Unfortunately, there is such a natural 

 attraction between the cultivated black currant and the blister rust fungus, 

 that these plants become infected manv miles from diseased white pines. 

 When black currants do become diseased, they act as centres from which 

 the rust spreads very rapidly to currants and gooseberries and to white pines. 

 In addition, diseased black currants cause more severe and extensive damage 

 to white pines, than do other kinds of currants and gooseberries. 



Because of their vigorous habit of spreading the blister rust, cultivated 

 black currants are a serious menace to the white pine forests of Massachu- 



