328 BROOKLYN BOTANIC GARDEN MEMOIRS 
bulletin lists about 2,700 such insects and that it also lists 130 
important insects which have already been introduced into the 
United States. Ifa thorough canvass was made of foreign literature 
I have no doubt that as many plant diseases could be located and 
described which are likely to be introduced into the United States, 
and many of them produce as much devastation as the chestnut bark 
disease, the asparagus rust, the potato blight, the citrus canker, or 
many other diseases that could be named. Unfortunately, we have 
at present no corresponding manual of plant diseases that are likely 
to be introduced into the United States. : 
There has never been a time when the danger from imported 
diseases and pests was so great as now. Commerce in living plants 
has in recent years extended to the ends of the earth. I have in mind 
one nursery company which makes a specialty of novelties from the 
Orient. This company is distributing throughout the United States 
plant material from all parts of Asia. Most of the things that they 
bring in are woody plants, many related to our American species, and 
on account of our comparative ignorance of the botany and zoology 
of the Orient we have no idea what diseases and pests are coming in 
with Oriental material. The San Jose scale, the chestnut blight, and 
the citrus canker are only a part of those that have come in already. 
Not only is commerce being carried on with countries from which 
hitherto there have been only scattering importations of live plant 
material, but material brought in now is much more miscellaneous and 
reaches this country in a much shorter time. There is at present a 
limited amount of port inspection but too limited to be efficient and 
the canker diseases and many insects can not be detected by any 
sort of inspection. The roots of plants imported with earth about 
them can not even be inspected and such plants constitute a par- 
ticularly dangerous class of imported material. 
The white pine blister rust (caused by Cronartium ribicola Fischer), 
which I am here considering as a fairly typical example of the imported 
disease, has long been known in Europe. It apparently originated in 
Asia and spread in Europe upon Pinus cembra. When the American 
white pine (Pinus strobus) was introduced into Europe it proved sub- 
ject to the disease. The first authenticated record of importation of 
white pine transplants from Europe to the United States dates back 
only to 1899. From that time until prohibited by law such importa- 
tion was extensive, as such transplants could be imported more cheaply 
than they could be grown in America. There was, furthermore, a 
prevalent belief among nurserymen that white pine seedlings could 
not be successfully grown in America, a belief which has since been 
proved erroneous. 
