NOTES AND COMMENT 



The forest pathologists of the eastern United States have their 

 hands very full at the present time. The chestnut blight peril has been 

 overshadowed by the spread of the much-dreaded white pine blister 

 rust {Cronartmm rihicola), which promises to far exceed the former 

 in its ravages. The rust attacks five-needle pines, and like certain 

 of the grass rusts, must reach a second host in order to complete its 

 life-cycle. The second host in this case may be either the gooseberry 

 or the currant, wild or cultivated. The aecidiospores developed on the 

 pine host are spread in May and June, and the resulting mycelium on 

 gooseberry and currant bushes produces a yellow rust (uredospores) 

 on the abaxial surfaces of the leaves. Spores of the yellow rust are 

 shed from the first of June to the end of the summer and carry on fur- 

 ther infection of the second host over considerable distances (as far 

 as 20 miles). In late July another type of spore (the teliospore) which 

 must reach the white pine in order to germinate, appears on the same 

 mycelium that produced the uredospores. The mycelium in the pine 

 now undergoes a period of "incubation" varying in length from less 

 than one year to several years, then forms the white, blister-like aecidia 

 which appear on the surface of the bark and give the common name to 

 the disease. 



Up to date the white pine blister rust has appeared in thirteen 

 states and is now as far west as ]\Iinnesota. Estimates of government 

 foresters place the value of mature standing white pine endangered 

 in the eastern and western forests of the United States at $186,000,000 

 and $240,000,000 respectively. Infected nursery stock is the principal 

 agent of interstate dispersal, so that b}^ prompt action the western 

 forests may yet be saved. Measures recommended bj^ competent 

 foresters and pathologists for checking the disease are: destruction of 

 infected trees; quarantine of nurseries in infected districts; rigid govern- 

 ment inspection of all pine stock intended for planting; destruction of 

 all gooseberry and currant bushes in infected districts. The Novem- 

 ber issue of American Forestry calls attention to the progress of the 

 disease and prints a request for public aid in combating it. In the 

 same journal Spaulding and Hartley give an interesting popular 



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