Canadian Forestry Journal, May, li)lS 



1687 



truction by fire, unless it can be 

 eradicated or held in check. 



This disease is caused by a fungus. 

 The fungus attacks the living bark, 

 causing death by eirdling. All 5- 

 needled pines are susceptible, all 

 other kinds so far as is known are 

 immune. The disease continues 

 from year to year in an infected 

 tree, but cannot spread from one 

 tree to another. The fungus also 

 causes a leaf disease of Ribes (cur- 

 rants and gooseberries). All species 

 of Ribes are susceptible, but some, 

 such as the cultivated black, and 

 the red currants, more so than others. 

 The disease spreads rapidly from 

 Ribes to Ribes by means of spores, 

 wind or animal-borne, but with the 

 falling of the leaves at the end of 

 the season, the affected plants are 

 free from it and can be infected 

 again only from rusted pines. It 

 also spreads by spores from Ribes 

 to 5-needled pines, and this is the 

 vital feature with respect to the 

 disease on the pine. This relation- 

 ship was discovered in 1892. The 

 dependence of the fungus on these 

 two hosts is so complete, that with- 

 out both its existence is impossible. 

 Observations and tests so far made 

 have shown that under natural con- 

 ditions there is probably little likeli- 

 hood of the disease passing from 

 one host to another if they are sep- 

 arated by a distance of one-third 

 of a mile. 



Origin in Siberia 



The history of this disease is both 

 interesting and instructive. Its home 

 is in Siberia and the Ural Mts., and 

 its natural host is the stone pine of 

 Europe and Siberia — Pinus cembra. 

 Two hundred years ago our white 

 pine was introduced into Europe 

 and planted there extensively, for 

 ornamental purposes and in some 

 cases as a commercial forest proposi- 

 tion. About fifty years ago it was 

 observed that the rust on Pinus 

 cembra had spread westward and 

 had attacked the imported white 

 pines, and that, as so often happens, 

 it was more virulent on the new 

 host thfvn on its own natural host. 

 Now follows the storv of its intro- 



duction into the western hemisphere. 

 A little more than 15 years ago a 

 planting movement gained great im- 

 petus in America, and the cry was — 

 "Plant white pine." The American 

 nurseries were unable to supply the 

 sudden demand for pine seedlings, 

 and because of the greater cost of 

 production made no eftort to compete 

 with the established European nur- 

 serymen. The result was that vast 

 quantities were imported from Europe 

 and with little or no fpiestion as to 

 the health of the stock. Up to 1909 

 nearly 5,000,000 seedlings had been 

 imported, about 95% of this from 

 Germany, and distributed to hun- 

 dreds of localities in the U.S. and 

 Ontario. In 1909 it was discovered 

 that large numbers of the shipments 

 of that year were diseased. Then 

 the door was closed. Examination 

 proved that the 1908 shipments had 

 been bad, too, and there is good 

 reason to believe that diseased stock 

 reached our shores even earlier than 

 1908. The suspected plantations 

 that could be located were destroyed, 

 but the records did not reveal the 

 whereabouts of all of them, so that 

 \ye have waited with fear and tremb- 

 ling, though with some hope that 

 the danger had been averted. Three 

 years ago, however, the blow fell, 

 and reports from Ontario and a 

 dozen states announced more or 

 less serious outbreaks. Consterna- 

 tion has reigned, but state, provincial 

 and federal governments have lost 

 no time in determining the extent 

 of the affected areas and in attempt- 

 ing some control or eradication meas- 

 ures. Massachusetts, New York and 

 southern Ontario are known to be 

 especially hard hit. As yet our 

 great northern pine forests are scarce- 

 ly' reached; but it is unescapable 

 that they are in imminent danger 

 of wide>pread infection. 



Infections have been reported from: 

 Ontario and Quebec: Maine, New 

 Hampshire, Vermont, Massachusetts, - 

 Connecticut, Rhode Island, New 

 York, New Jersey, Pennsylvania, 

 Ohio, Indiana, Michigan, Wisconsin, 

 Minnesota, and South Dakota. 



To be Concluded in June Issue 



