THE MONTHLY BULLETIN. 



269 



All practical control of plant diseases and insect pests is based on two principles, 

 viz, the light against existing established evils and the prevention of their introduc- 

 tion from the outside into territories not yet invaded. The former yields remarkable 

 results in a great many troubles, such as San Jose scale and many crop and orchard 

 diseases, hut is almost hopeless in others unless unlimited funds are available. The 

 latter consists in a well-reasoned and organized quarantine. 



It has become necessary in recent years to organize a vigorous campaign against 

 two most serious forest tree diseases, the white pine blister rust and the chestnut 

 bark disease. The latter is firmly established in the East. The white pine blister 

 rust has gained an alarming foothold in the eastern part of the United States, but 

 still the light presents good chances for success if only it is kept up with energy and 

 perseverance (Fig. 76). The western part of the United States is still free from 

 both. It is imperative that both be kept out of the West by all possible means. 



WHITE PINE BLISTER RUST. 



The white pine (I'inus atrobus) is a typically American tree, but the fungus 

 which causes the white pine blister rust is not indigenous to this country. It came 

 to the United States from abroad. 



Fig. 76. — Thick stand of 13-year-old white pines heavily infected with 

 white pine blister rust (Peridermium strobi). Each white tag marks a sep- 

 arate infection. (Ulioto by J. F. Collins.) 



As contrasted with North American forests, those of Europe are poor in species. 

 With the progress of European forestry and the economic necessity of raising their 

 productiveness to the highest pitch, the attention of foresters, in the search for 

 promising foreign trees, was from an early date on attracted by the white pine. This 

 species combines a number of most valuable qualities. It is unusually fast-growing 

 and its yield in lumber is extraordinarily high, compared to other pines. It is not 

 particular as to .soil, growing luxuriantly in swampy ground and doing very well in 

 sandy ^"ils. The tree resists even the lowest winter temperatures. The wood is 

 very durable; it works easily, does not warp or check. 



Tin- tree was first introduced into England in 1705 and has spread from there 

 over the continent. Some plantations of Germany are more than a hundred years old. 



