BLISTER RUST OF PINES (Peridermium stroll) 

 EUROPEAN CURRANT RUST (Cronartium ribcola) 



/""Blister rust of pine has recently been found in this and other 

 near-by States on a few white pine seedlings imported from Ger- 

 many. Acting under authority of the State law and with the 

 co-operation of all persons interested, this Department hopes to 

 eradicate the disease promptly. The white pine (Pinus strobus), 

 native to America is recognized as one of the most beautiful of 

 trees and its value for timber is enormous. Judging by the experi- 

 ence of other countries where the blister rust disease prevails, it 

 may be said that the American white pine is in grave danger so 

 long as this disease exists in our country. Some foreign nursery- 

 men have abandoned the business of white pine growing because 

 of the losses on this account. 



The recently increased interest in the subject of reforesting 

 astareas_pf our lands not adapted for farming purposes has led 

 to a demand for coniferous seedlings far in excess of the supply. 

 Millions of these seedlings have been imported from nurseries in 

 other countries where the climatic conditions and cheap labor favor 

 such production. A large proportion of these trees are grown 

 from seeds of the pine which are annually exported from the 

 United States. Young trees are suitable for forest planting when 

 from two to three years old. 



The disease has been found upon a number of the three-year 

 seedlings imported in the spring of 1909. Unfortunately the 

 presence of the fungus is not apparent at or before planting time. 

 Tt develops sufficiently in June to be identified by the spore forma- 

 tions. The prominent character of the disease quickly disappears 

 and by the first of July it can hardly be found even by the closest 

 expert examination. The same appearances recur the following 

 year. It is known that when the fungus once becomes fixed in a 

 pine tree it will remain until finally the tissues of the tree are so 

 involved as to kill it. Affected three-year seedlings are likely to 

 die the first year of planting, but this is not an invariable rule. 

 Two-year seedlings may be infected and not develop spores until 

 they are three years old. Such seedlings imported from abroad 

 should be very carefully inspected next May and June and all 

 suspicious plants removed and burned as described below. The 

 stages of growth of this fungus are complex and not generally 

 understood. It does not spend the full cycle of its life on the in- 



3 



