PROTECTING THE UNITED STATES FROM PLANT PESTS 



21 



ceptions, the European 

 tussock moth, Notolophus 

 antigua, an injurious for- 

 est and ornamental plant 

 insect, was found in con- 

 nection with no less than 

 67 different shipments of 

 plants from Holland, in- 

 volving some 16 different 

 kinds of ornamental 

 plants. Such important 

 and easily detected pests 

 as the gipsy and brown- 

 tail moths were found re- 

 spectively, in the egg and 

 larval stages on no less 

 than 63 different ship- 

 ments of plants. These 

 are merely typical illus- 

 trations out of many 

 which could be afforded. 

 Practically all of these 

 injurious insects which 

 have been thus inter- 

 cepted have been carried 

 by the aerial portions of 

 the plants and include 

 few, if any, of the often 

 more dangerous species 

 hibernating in the soil 

 about plants imported in 

 balls of earth or in pots. 

 It is not possible, with- 

 out the destruction of the 

 plants, to disintegrate 

 and make an adequate 

 examination of such soil, 

 and no disinfection of 



THE JAPANESE BEETLE BREEDS IN THE SOIL 



A spadeful of soil taken in a New Jersey meadow in the 

 infested district is illustrated above. The eggs of the Japanese 

 beetle are placed in the soil in pasture and other uncultivated 

 lands during the summer, and the insect develops as a white 

 grub, and later transforms into a pupa or chrysalis, and eventu- 

 ally into the mature beetle. The only method of reaching the 

 weevil in the soil is by soaking it with powerful poisons — a very 

 expensive and not altogether effective treatment. 



such 



sou 



has 



proven possible without killing the plants. 

 PLANT DISEASES INTERCEPTED SINCE 1912 



There is risk of entry through the 

 medium of soil of a vast number of in- 

 sects which, as elsewhere indicated, may 

 have no relation to the plants imported, 

 but may become important enemies of 

 various field crops. The possibilities of 

 such introductions of insects with soil are 

 very large and are not theoretical, as in- 

 dicated by the examples of such importa- 

 tions already given. 



It is even more difficult to exclude 

 plant diseases than it is insect pests, and 

 in the case of many such diseases in- 

 spection is very often a safeguard of lit- 

 tle importance. Many of these diseases 

 are not discoverable by inspection or may 



develop to a visible stage only after a 

 period of months or even years after 

 the plants have been imported. 



The pine blister rust, for example, can- 

 not be determined often for five or six 

 years, and other similar diseases may be 

 in the tissues of the host plants and re- 

 main undiscoverable by any technical 

 method except by planting and growth 

 for a long period in quarantine. 



With respect to the risk of introduc- 

 tion of dangerous diseases from Europe, 

 it is significant that of the three serious 

 diseases of forest trees that have been 

 introduced into this country in recent 

 years, two of them — the white pine 

 blister rust and the European poplar 

 canker — have come from Europe, where 

 both of these diseases are well known, 

 and in spite of the protection of Euro- 



