490 



THE GARDENERS' MAGAZINE. 



June 29, 1912. 



one to suppose that the interests of horticul- 

 ture have been overlooked or neglected. 



Those countries which have led the way 

 I'n legislating- on the subject of the pests 

 and diseases of plants have generally had 

 public attention roused to the necessity of 

 taking action by some sudden and almost 

 dramatic disaster. Some new pest, whose 

 life history has been unknown, has appeared 

 in their midst and swept like an epidemic 

 across the country, destroying the crops and 

 ruining the cultivators of the soil. In Eng- 

 land, with one notable exception, we have 

 have been spared that experience. 



Freedom from Serious Pests. 



This freedom from serious pests that we 

 have so long enjoyed is due not to any acci- 

 dental good fortune, but in a great measure 

 to the geographical position and climatic 

 conditions of these islands. The destructive 

 injects, which have spread across the Conti- 

 nent of Europe, without regard for national 

 boundaries, have been checked by the sea 

 from invading England. The prevailing 

 south-west wind reaches this country from 

 the Atlantic, where there are no insect pests 

 that attack crops. It is true that, owing to 

 the large quantities of fruit and agricul- 

 tural produce imported every year some 

 foreign pests may be, and are, introduced, 

 but most of them are parasites on tropical 

 or semi-tropical jiants which can with dif- 

 ficulty survive a year of English weather. In 

 other countries whose area is larger their 

 acclimatisation and subsequent spread is 

 rendered easier by the gradual transition of 

 the climate from semi-tropical to temperate 

 conditions without any natural barriers to 

 check their progress. 



The small size of England, and the fact 

 that the climate varies but little from one 

 end of the island to the other makes such a 

 risk improbable. And even if any such pest 

 were introduced and established itself it 

 would not find the conditions favourable fnr 

 rapid breeding during the summer, so that 

 a second winter would find only a slight in- 

 crease. But there are other circumstances 

 which have contributed to keep England free 

 from any overwhelming incursion of insect 

 pests. 



Agriculture has been practised here for 

 many centuries, and the crops that are now 

 raised differ very little from those that were 

 raised a hundred years ago. Farmers and 

 fruit-growers are therefore not likely to be 

 exposed to the risks which beset pioneers in 

 a new country, where the insects that 

 formerly lived on native weeds attack their 

 cultivated crops, or to which pests may be 

 imported from abroad without the parasites 

 that keep them down in the country from 

 which they were brought. It is true that 

 the foregoing remarks apply chiefly to in- 

 sect pests, and are not equally applicable to 

 those more insidious diseases caused by 

 microscopic fungi, to which the constant 

 fall and the muggy weather that so often 

 prevail during the growing season render 

 the crops particularly liable. But with the one 

 ejception of the potato dieea^, caused by 

 Phytophthora infestans, already referred to, 

 the fungus diseases that have been intro- 

 duced into this country have not spread with 

 CTeat rapidity, or caused serious loss in the 

 t> few years after they have made their 

 first appearance. Even the American Goose- 

 berry Mildew (Sphaerotheca mors-uvae) which 

 was first detected in 1906, and had certainly 

 been in the country for some year^ pre- 

 viously, did not reach certain important 

 fruit-growing districts for some years, in spite 

 of the favourable seasons for the spread of 

 such diseases that prevailed, and has not yet 

 established itself in the south-western coun- 

 ties. 



Danger of the Introduction of 



large 



of disease. 



.crer to be feared 



try is of a very difterent order from that 

 which be&ets more extensive countries, espe- 

 cially th<>:e which are still thinly populated, 

 where farms are large, and means of com- 

 uiunication titiU imperfect. In an old and 



densely-populated country th^re are few 

 localities which are not under cultivation of 

 some kind. The area classed as mountain 

 and heath in England is very small, and 

 though the districts covered by towns are 



and numerous, there are gardens 

 attached to the hour^s among the mountains 

 and in the towns, where fruit and vegetables 

 are grown which might harlx>ur diseases and 

 pests, and render the task of extermination 

 correspondingly difficult. Even in the dis- 

 tricts that can properly be described as agri- 

 cultural there are no natural boundaries 

 which would chock the spread 

 \\ hile the means of communication by human 

 as well as natural agencies are rapid 

 and easy. The maps that have been 

 hung in the Exhibition show how few 

 fruit-growing areas there are which are at all 

 isolated. 



The danger, therefore, which lies before 

 the fruit-growers of this country is the intro- 

 duction, as it were l-y stealth, of some new 

 pest, its gradual spread until it is firmly 

 established before it is discovered and iden- 

 tified, and the difficulty of exterminating the 

 post to which such circumstances give rise. 

 In order to meet this danger it is essential 

 that a constant watch should be kept not 

 merely among English fields and gardens 

 to discover and control any new dangerous 

 pest that may be x^cported as attacking Eng- 

 lish crops, but also through foreign publica- 

 tions, whether official, scientific, or popular, 

 on the appearance of such pests in the coun- 

 tries that lie on the other side of the Channel, 

 or with which we have constant intercourse 

 by trade. It is for this reason that the plant 

 diseases service of the Board of Agriculture 

 and Fisheries has arisen in the Intelligence 

 Division, and it is this circumstance which 

 ha^ influenced and moulded the whole charac- 

 ter of English legislation and administration 

 on the subject of diseases of plants. 



Leg^islative Enactments. 



The Destructive Insects and Pests Acts of 

 1877 and 1907 by virtue of which the phyto- 

 pathalogical service of this country is con- 

 ducted, had their origin in the agitation 

 created by the introduction of the Colorado 

 Beetle (Doryphora decemlineata) in 1877, and 

 their completion in the alarm due to the dis- 

 covery in an English fruit garden of the 

 American Gooseberry Mildew (Spaerotheca 

 m.or*5-uvae), both of them pests from the New 

 A\'orld. The Acts contemplate the issue by 

 the Board of Orders to prevent the introduc- 

 tion of destructive insects and pests from 

 aVroad, and their control and, if possible, 

 their eradication after they have been intro- 

 duced. The duty of administrating these 

 Orders is placed on the Local Authorities, 

 though a large part of the work is carried 

 out by the Board's officers, so that there is a 

 double system of inspectors, those appointed 

 by the Local Authorities, who have a special 

 knowledge of local (Conditions, and those ap- 

 pointed by the Board, whose object is to 

 secure uniformity of administration through- 

 out the country. But both classes of inspec- 

 tors send in their reports to the Board, so 

 that the Central Authority is in constant 

 communication with all the districts in which 

 disea*se prevails or where inspectors are at 



work. 



Before describing the method by which the 

 reports are prepared and submitted, it will 

 l>e necessary to give some account of the 

 principles on which the Orders of the Board 

 are drawn up, and the procedure which they 

 require to be carried out. This had to be 

 settled while the Act of 1907 was being 

 drafted, and a memorandum was prepared 

 in which attenion was drawn to the fact that 

 all destructive insects and pests with which 

 agriculturists in England are likely to be 

 troubled may be classified under three heads. 

 First, there are those pests which are in- 

 digenous or have at least been prevalent so 

 long in this country that they are distri- 

 buted more or less 'evenly throughout the 

 land. These pests, though they frequently 

 cause serious injury, seldom, if ever, take 

 the form of an epidemic. Their virulence is 

 scarcelv affected by any abnormally wet or 



coun- 



dry season. They often yield fo simple 

 treatment, and at any rate there is hot the 

 slightest hope that they can be exterminated 

 by any State or municipal interference. The 

 number of such pests is large, and their 

 names will readily occur to any farmer or 

 fruit-grower. They include the Winter Moth 

 (Cheimatobia brumata), the Wireworms (Ela- 

 teridae), the Woolly Aphis (Schizoneura lani- 

 gera), Apple Canker (Nectria ditissima), and 

 Potato Disease (Phytophthora infestans). 

 These pests are described in the Board's leaf- 

 lets, thousands' jcff which lare distributed 

 every year free of cost, or at a nominal 

 charge, and they must be left to the indivi- 

 dual growers to contend with. Those who 

 cannot identify them are invited to 

 specimens to the Board for determination and 

 advice as to treatment. 



The second class includes those pests which 

 have only recently been introduced, or whicl 

 are only to be found in certain 

 ties. These pests, if likely to prove 

 dangerous to to spread to districts 

 hitherto unaffected, can be made the sub- 

 ject of a special Order, if there is any pros- 

 pect that they can be controlled by such 

 means. The two diseases that have been 

 treated in this way are American Gooseberry 

 Mildew (Sphaerotheca mors-uvae) and Wart 

 Disease of Potatoes (Synchytrium endobioti- 

 cum), but others might be mentioned. It is 

 these pests, of course, which claim the chief 

 attention of the Board and the Local 



Authorities. 



The third class includes those pests which 

 have not yet been found in England, but 

 whose introduction is to be feared, and those 

 which have been reported sporadically for 

 which no adequate treatment has yet been 

 found. Among these are to be numbered the 

 San Jose Scale (Aspidiotus perniciosus), the 

 Potato Moth (Phthorimaea operculella), the 

 Japanese Fruit Scale (Diaspis pentagona), or 

 the Large Larch Sawfly (Nematus erichsoni), 

 which, however, has perhaps been longer in 

 this country than was at one time supposed, 

 and the Tomato Canker (Mycosphaerella 

 citrullina). Though it is of the utmost im- 

 portance that these should be kept out of the 

 country, or dealt with adequately, where 

 they are found nothing can be done in ad- 

 vance. Preparations can be made for dealing 

 with them promptly when they appear, or 

 investigations carried out as to the best and 

 most effective treatment of those already 

 with us. As they assume more dangerons 

 proportions or a suitable method of control is 

 found, they should be removed from the 

 third category to the second. A fourth class 

 was subsequently added to which reference 



will be made later on. 



The lines laid down in this memorandum 

 have generally been followed in the prepara- 

 tion of the Board's Orders in connection with 

 Destructive Insects and Pests. Certain other 

 distinctions have also been drawn between 

 the pests in the second and third classes 

 which have led to a variation in the proce- 

 dure for dealing with each. Thus although 

 it is considered a cardinal principle that the 

 occupier of any premises on which aiiy 

 scheduled pest may exist or have recentlv 

 existed is bound under a penalty to report 

 the fact to the proper authority, the pests iij 

 the second class are considered to be so wei 

 known that the plea of ignorance otine pest 

 is not considered a good defence. Those in 

 the third class might easily fail to be de- 

 tected, and in this case a fine can only 

 imposed if the occupier can be convicted oi 

 " knowingly " failing to report. Again, wlien 

 one of the pests on the second list is ajs- 

 covered a notice is served on the occupies 

 declaring his premises "infected premise^, 

 and prohibiting the movement from them oi 

 any plant which might convey the dise^e to 

 other premises, except by licence. ino^ 

 parts of the plant which are used for- human 

 food are exempt from this rule if' 

 fit for consumption. The pests of the tliira 

 class are treated differently, and no at- 

 tempt is made to define- the infected place. 

 The reports refer merely to the parish i" 

 which the premises lie. 



^T<> be continued.) 



