TREATMENT OF DISEASES INJURIOUS TO ORCHARD CROPS. 75 



fumigate all stock before it is sent out. At the same time, with 

 flourish of trumpets they do not forget to proclaim abroad the protection 

 which they are giving to their customers by this operation. 



It may be remarked, by the way, that fumigation with hydrocyanic 

 acid gas has been tried in greenhouses.* It cannot be said that experi- 

 ments have shown its limitations as to safety with all classes of plants, 

 but it has been used with excellent results on low growing plants, as, for 

 example, violets and lettuce. On chrysanthemums, carnations, and 

 plants of taller habit than violets it may be used when plants are small 

 and' low. It cannot be used safely where plants grow near the glass, or 

 where loosely constructed houses permit draughts during the process of 

 fumigation and tend to cause banking of the gas. 



Spraying Apparatus. 



When the value of Paris Green as an insecticide was first demonstrated 

 the conditions w^ere such as to force the extension of its use for the 

 protection of various crops in field, orchard and garden. Various kinds 

 of apparatus for the application of this and other poisons of similar form 

 soon began to be devised. An exhibition now of these really primitive 

 appliances would remind one of a museum of weapons and armour of 

 ancient and medieval ages, so completely have they been replaced among 

 progressive agriculturists and horticulturists by improved apparatus. 



The application of insecticides in liquid form in most cases gradually 

 displaced other methods, but it was not till after the introduction of 

 Bordeaux Mixture that spray pumps came to be a common article of 

 farm and garden machinery. The Bordeaux Mixture was at first used as a 

 thick heavy mixture. Repeated experiments afterwards demonstrated 

 that when diluted so as to pass readily through force pumps and spray 

 nozzles it could thus be applied most rapidly and effectively. Then the 

 spraying apparatus which had already been developed for applying Paris 

 Green and such insecticides was at once pressed into service for the 

 application of the Bordeaux Mixture. As the merits of Bordeaux Mixture 

 became better known the demand for spraying machinery naturally 

 increased. This, in turn, led rival manufacturers to strive to bring out 

 the best appliances which they could put on the market at reasonable 

 prices. Improvements in spraying apparatus have kept pace with the 

 demand for spraying machinery. There was at first, quite naturally, 

 among farmers and fruit growers a greater demand for the less expensive 

 spray pumps of comparatively small capacity. But as the practice of 

 spraying became more thoroughly established among them, the bucket 

 pumps, knapsack sprayers, and the weaker types of barrel pumps quite 

 largely gave place to the stronger types of hand pumps or to pumps 

 driven by horse-power or steam. In barrel pumps an important improve- 

 ment was made when pumps of the type of the so-called Eclipse and 

 Pomona were introduced. In this type of apparatus the pump is placed 

 near- the bottom of the barrel or tank, so that it is not necessary to lift the 

 liquid the length of the barrel before it can be forced through the pump 

 asimust be done with pumps which are mounted outside the barrel or tank. 



* See also li.H.S. Journal, vol. xxv, p. 305 



