FARMERS' INSTITUTES. 71 



of this early application will generally be repaid, with other fruits the 

 use of Bordeaux mixture just before the flower buds open will be even 

 more effective. The principal objection to putting off the first applica- 

 tion until this time is that rains may occur during the two or three days 

 when the remedy will be most effectual, and when one has large or- 

 chards the period during which spraying will be most effectual is not 

 suflficienth^ long to permit the work to be done. The best results will 

 be secured when the early application of copper sulphate solution is 

 made, and this^ is followed bj^ the use of Bordeaux mixture upon as 

 many trees as can be sprayed after the flower buds form, but before 

 the}^ open. For powdery mildew the use of a solution of liver of sulphur 

 at the rate of one ounce in three gallons of water will be even more 

 effectual than Bordeaux mixture. 



The number of applications that will be needed of any fungicide will 

 depend largely upon the season, but at least two should usually be 

 given after the trees blossom, and three or four will often be desir- 

 able. 



For the destruction of insect pests there are two classes of remedies 

 upon which the principal reliance should be placed. One of these con- 

 tains the arsenites and other materials that will destroy insects on being 

 taken into their stomachs. These remedies can only be used against 

 biting and chewing insects, but for all of this class that feed upon the 

 exterior portions of plants they are ordinarily the best that can be se- 

 lected. 



There are, however, a large number of sucking insects, such as plant 

 lice and the various scales, for which these remedies cannot be used, 

 and recourse must be had to such as will kill them by contact or act 

 through their breathing organs. 



Paris green is the most commonly used arsenite, and in an unadulter- 

 ated form contains about 50 per cent of arsenic. It sometimes troubles 

 by quickly settling in the water and by burning tender foliage. London 

 purple contains slightly less arsenic, united with lime, and is more 

 likely to burn the foliage, but will remain suspended in the water for a 

 longer time. These arsenites are used in water at the rate of one 

 pound in from 100 to 200 gallons, but when the stronger preparation 

 is used, especially if upon plants with tender foliage, it is desirable to 

 use two pounds of lime to each 100 gallons, unless the arsenite is to 

 be added to Bordeaux mixture. For ordinary spraying purposes it is 

 always well to combine an arsenite with Bordeaux mixture, as both are 

 generally needed, and, if applied at one time, it will be to the benefit of 

 both, besides the saving of labor. 



White arsenic has recently come into use as a substitute for paris 

 green. Its cost per pound, wholesale, is less than one-half that of 

 paris green, and but little more than one-half as much need be used 

 to secure the same results, so that the actual cost of white arsenic as 

 an insecticide is but about one-fourth that of paris green. To be used 

 with safety upon plants it must be dissolved and then rendered insol- 

 uble by combining it with lime. This can be done by boiling one pound 

 of arsenic with two pounds of freshly slaked lime in two gallons of 

 water for forty minutes. The arsenite of lime thus formed can be 

 added to Bordeaux mixture, one pound of arsenic, prepared as above 

 described, being sufficient for 150 gallons for use upon potato beetles, or 



