30 



THE SPRAYING OF PLANTS. 



Mr. B. T. Galloway, Chief of the Division of Vegetable Pathology, 

 U. S. Dept. of Agriculture, says in a preface to a work on the above 

 heading by Mr. E. G. Lodeman : — " In looking back over the past 10 

 or 1 2 years, it is difficult to realise the rapid advance made in com- 

 bating ihe insects and fungi which attack our cultivated plants. It is 

 not going too far to say that the discoveries made within this period 

 have worked almost a revolution in certain lines of agriculture." 



Mr. Lodeman's treatise is a very valuable one, and the following 

 extracts are given to explain the importance of the subject : — 



" Man's power over the organisms which injure cultivated plants 

 was never so great as it is at the present time. One by one these ene- 

 mies have been carefully studied, the history of their lives determined, 

 and their habits observed. Only by understanding them thoroughly 

 can proper steps be taken to check their ravages in the most t conomi- 

 cal and efficient manner ; yet it is within comparatively recent years 

 that this first step was taken to obtain the mastery over them. For- 

 merly, when a pest injured a plant, it was no uncommon practice to 

 apply any remedies or materials that c-ime to hand, regardless of their 

 probable efficiency. It was not generally the weakest point of the or- 

 ganism that was assai'ed In many cases, it was not even the proper 

 organ'sm which was held responsible for the injury. Nevertheless 

 many valuable discoveries came from these varied and desultory treat- 

 ments, and some of the remedies most highly prized to-day were dis- 

 covered merely by chance, not very many years ago. 



" Present knowledge and methods of investigation, largely founded 

 upon this experience, enable us to arrive at conclusions which, from 

 the outset, are founded upon a sound and logical basis. Tt is fortunate 

 that this is the case. The number of the enemies of cultivated plants 

 is either now more numerous than formerly, or the attacks are much 

 more energetic. It is undoubtedly true that the maladies of cultiva- 

 ted plants are much more widespread. This fact is mostly due to the 

 greater food supply, and to the greater ease with which most of the 

 injurious forms can pass from one part of the country to another, be- 

 cause the cultivated areas lie so close together. If a plant is grown 

 to any considerable extent, it is eas} r for its enemies to spread over the 

 entire region in which it is cultivated. Physi' al barriers are almost 

 without value in checking this sp>eadingof disease. The ocean is 

 only a partial exception, since such close means of communication have 

 been established between all parts of the globe that this obstacle is 

 now of little avail. Some diseases have not yet been able to ovei"pass 

 it, but as it has proved of little hindrance in so many cases, it is pro- 

 bable that ultimately the enemies and diseases of plants will be as 

 widespread as are the plants upon which they flourish. "Weedy plants, 

 insects, and possibly also fungi, are frequently more destructive in a 

 new country than in their old home. They are freed from the enemies 

 or conditions which formerly kept them in check, and in some cases 

 they are the cause of very serious disturbance, although originally 

 they may not have been markedly destructive. 



"Farmers and fruit growers cannot fence out the many forms of insects 

 and fungi which live upon their crops, and which are as anxious for a 



