June 1, 1912. 



THE GARDENERS' MAGAZINE. 



[supplement] 



13 



has come into force. That the San Jose Scale 

 hitherto never gained footing in Europe is, 

 in the opinion of the Profe&sor, not because 

 of the prohibitive measures enacted in several 

 European countries concerning the importa- 

 tion of American stock. The difEerence in 

 climate, in soil, in cultivation, furnish 

 reasons why it cannot tlirive in the&e regions. 



In the second place, attention has to ibe 

 paid to the fact that sometimes a disease 

 or insect pest is not nearly so destructive in 

 the country of its origin as in the country 

 where it is introduced. 



The vine Phylloxera is a striking instance ; 

 it is not at all such a bad pest in America, 

 its native country, as in Europe. On the 

 other hand, the Gipsy Moth and the Brown- 

 tail Moth are not among the promi- 

 nent injurious insects in Europe, while in 

 some of the United States of America, where 

 they are introduced from the Old World, 

 they play havoc with all plantations and 

 parks. 



the American Gooseberry mildew was ob- 

 served for the first time in Holland ; two 

 years ago it spread over a great deal of the 

 country, and it appeared to be a grave 

 menace to gooseberry cultivation in some 

 districts. The Dutch Phytopathological 

 Service has done its utmost to control this 

 pest. In some districts the efforts to ex- 

 terminate it were crowned with success, in 

 other parts they had not yet been success- 

 ful. In the meanwhile, a rather rigorous 

 law was passed enacting measures to pre- 

 vent the inland spread of the disease. The 

 burgomaster of each community where the 

 disease prevails is authorised by it to order 

 the means of exterminating which are con- 

 sidered necessary and useful by the chief 

 of the Phytopathological Service. So the 

 cutting off and burning of the diseased parts 

 of the shrubs can be ordered. If need be, 

 the uprooting and burning of entire shrubs 

 is ordered, and, anyhow, the transport of 

 infected shrute, cuttings, or fruits, and even 



great obstacles they offer to trade, and the 

 uncertainty of their effect. 



In dealing with the question : Can inspec- 

 tion at the port of landing be relied upon 

 as a method of preventing the introduction 

 of plant diseases from abroad? The answer, 

 said the Professor, was. No. 



As a rule, the great quantity of imported 

 stock and the solidness of its packing will 

 make it impossible to inspect thoroughly. Let 

 it be granted for a moment that the potatoes 

 imported from abroad must be inspected at 

 the port of entrance for the presence of black 

 scab, which dangerous pest in it© first stage 

 only is perceptible at the eyes of tiie tubers 

 by careful examination. The inspector would 

 be obliged to look attentively at nearly every 

 potato in every imported case ; for even when 

 only one in a thousand of the potatoes 

 destined for seed is attacked, the disease can 

 make its introduction. 



Talking into consideration the enormous 

 quantity in which cases full of conifers. 



AN 



ATTRACTIVE AIIKAXGKMEXT OF NEW HOLLAND AND OmEE PLANTS, 



Exhibited by Messrs. Stuart Low and Co., Bush Hill Park, N, 



ilow often, on the other hand, a pest wliicli 

 one would like to keep outside the frontiers 

 proves, after being introduced, not to be so 

 aestructive as it was expected to be. In 

 and 1878 Europe stood in awe of the 

 ^lorado beetle, the introduction of which 

 ^^P^cted to be the ruin of the cultivation 

 oi the most indispensable article of food, 

 h^ ^^^^^^a^ds, when the public attention 



Wi ^^^^^^ ^^^y ^^^^ Colorado 

 W r+i.^^^ "imquestionably present for at 

 ^ast three year^from 1884 to 1887— in the 

 potato fields at Torgau (Germany) without 

 tievelopmg to a destructive pest. 

 f*«t^ ^J'^^^ being misunderstood, the Pro- 

 aWi^ .^^^i^ctly stated that he was not an 

 a^^.^ <>PPf>nent to prohibitive orders as 

 wh^ checking pests. Especially 



infr^ prevention of the re- 



extl^^''*'''^ ^ P^st ^^lich is alDOut to be 



fromT" ^^^^ S^^^ an instance 



nis own experience. Four vears ago 



of sound shrubs, from infected grounds or 

 premises, is forbidden. 



Having thus taken all possible pams to 

 exterminate the disease, it would, in his 

 opinion, be a great mistake to run the ven- 

 ture of re-infection from abroad. In the 

 present circumstances he considered it quite 

 reasonable, for the Dutch Government has 

 completed the measures by forbidding the 

 importation into Holland of gooseberry, cur- 

 rant and raspberry bushes. Indeed, this 

 prohibitive me^isure should have been taken 

 before the di^ase passed over the frontiers, 

 for this alarming pest already having spread 

 to a great extent in several countries ot 

 Europe, which in soil, climate, and culture 

 are not considerably different from those of 

 Holland, it was probal^le that it would come. 



But however unavoidable, in some cases 

 prohibitive measures may be, yet authori- 

 ties are cautioned onc^ more not t<> t^lfc 

 refuge in them heedlessly, because of the 



evergreens, shrubs, and plants are shipped 

 in the export sea^son from Holland to other 

 countries, we must be convinced that it is 

 impossible for the experts at the port of 

 landing to inspect these quantities as care- 

 fully as to be secured against the introduc- 

 tion of nests of Brown-tail Moth, egg-clus- 

 ters of Gipsy Moth, woolly aphis, scales, nec- 

 tria, monilia, American Gooseberry mildew, 



and so on. i - i • 



It was not denied that the use which in 



some cases may be derived from inspection 

 at the port of landing, for when fungus or 

 insect pests are found on the imported stock, 

 and when this stock is burnt or returned at 

 the consigner's charge, he gets the wojst 

 of it. Experience keeps a dear school lor 

 him, and he may serve as an example for 

 his fellow-nurserymen. 



Professor Ritzema Bos then proceeded to 

 deal at some length with the question of 

 5n«TW>f^tion of stock, and the granti — - 



