FOREST COMMISSIONERS REPORT. 133 



Pennsylvania, New Hampshire, Vermont, Massachusetts and 

 Connecticut have been found to be infected with this disease. 

 Plantations in other states are under suspicion. 



Unlike the chestnut blight, the blister rust cannot spread 

 directly from one pine to another pine. It has two hosts ; one 

 stage of the disease lives in the bark of five-leaved pines, the 

 other develops on the leaves of currant and gooseberry bushes, 

 both the wild and the domestic species. The stage of the dis- 

 ease on currants and gooseberries can spread to other currants 

 and gooseberries, and also to pines. There is but one stage of 

 the disease on the pines, and this can spread only back to cur- 

 rants and gooseberries. Therefore the disease has a vulnera- 

 ble point of attack; namely, the complete elimination of one 

 or the other of the hosts in the sections where the disease is 

 found. The pine forests, as a whole, are infinitely more valua- 

 ble'than the currants and gooseberries; therefore, the latter are 

 the ones to be destroyed in the sections where the disease has 

 been found. Where the disease has been located, the safe 

 thing to do is to destroy all currants and gooseberries in the 

 immediate vicinity, whether or not they are infected, as well 

 as all pines that are infected. 



The total distance that the disease will spread in one season 

 is not, and probably cannot be definitely determined, but one 

 point is certain, namely, that it will surely spread in this coun- 

 try, wherever pines and currants or gooseberries are found in 

 the same vicinity. Wild currants and gooseberries are found 

 practically all over the country, which makes the spread cer- 

 tain, unless drastic measures are taken to prevent it. The max- 

 imum distance that the disease will carry from currants and 

 gooseberries to pines, and vice versa, has not been definitely 

 proved, but certainly that distance is several hundred yards. 



The disease is known to attack the white pine (Pinus stro- 

 bus), the Pacific Coast sugar pine (Pinus lambertiana"). and 

 the white pine of the northern Rocky Mountain region (Pinus 

 monticola). There are six other five-leaved pines which are 

 believed to be susceptible. The value of the pines that will 

 certainly be attacked in the United States is estimated by our 

 foresters to be over $425,000000. 



Unless adequate steps are taken against this disease at once, 

 the future value of the young second growth white pine will be 



