EXPERIMENT STATION REPOET. 627 



such, adds nothing to the Paris green; it is merely the carrier by 

 means of which the poison is spread over a large surface. The water 

 dries off soon after the application and leaves a very fine coating of the 

 dry green. Any other method of producing the same mechanical 

 result is likely to be equally effective. Water is sometimes difficult 

 to get in quantities necessary for spraying purposes, especially in 

 hilly regions or in the arid plains of the central and further west. 

 This has induced an effort to develop dusters in the form of rotary 

 fan-blowers to apply the same poison mixed with the dry hydrate or 

 one of the prepared forms of ground lime. In the form of a dry 

 application on potato vines, New Jersey growers are familiar with the 

 general principle involved, and not a few up-to-date fan-blowers are 

 in use in the State for this purpose. It seems a far jump from a 

 blower to cover a potato vine to one that will cover a tree, nevertheless 

 is has been made, and '"spraying" an orchard with dust is no longer a 

 difficult task, even if the trees be of good size. 



In New York and in Delaware experiments have been made' and 

 reported upon by the Experiment Stations, but there is no record of 

 any considerable number, of horticulturists following the method. 

 In New Jersey there are only two of the large orchardists using the 

 dust process, and here I had a chance to see the practical working of 

 the machines. There is no doubt that a tree can be more rapidly cov- 

 ered by a cloud of dust than by a spray, and, when properly made, 

 the application seems to be quite as complete. The work with a good 

 machine is easier, and there is much less carting. A surprising 

 amount of surface is covered by the dust, and its cost per tree is de- 

 cidedly less than where the liquid spray is used. In the Delaware 

 and New York experiments a double purpose was held in mind, and 

 both copper sulfate and Paris green were used. The New York con- 

 clusions are, in brief: Labor and expense of applying dust sprays 

 appears to be less than for sprays in liquid form. Six applications 

 of dust were not more effective on apple than two applications of Bor- 

 deaux. Brown rot on peach and plum were not prevented; but the 

 experiments are not conclusive. Dust should be applied in early 

 morning or late afternoon and powder must be strictly dry. Damp, 

 not wet, conditions of atmosphere and tree are desirable, if not 

 essential. 



The Delaware conclusion is a little more favorable in the results 

 on apples, and it is believed that for some purposes the dusting may 

 replace liquid sprayings. 



