KEMEDIAL MEASUEES. 83 



The owner of this vineyard is greatly pleased with the results 

 obtained by the treatment described above and is satisfied that a con- 

 tinuation of these methods will in another season restore his vine- 

 yard to its full bearing capacity of 1905. It might be added that 

 previous to this experiment Mr. Mosher was very skeptical regarding 

 the possibility that this pest could work such havoc in vineyards 

 and also as to the value or necessity of a spray treatment. During 

 this experiment, however, he has become a thorough convert, and 

 is satisfied that the intelligent use of a poison spray has been the 

 chief factor in the restoration of his vines. 



SPRAYS. 

 ARSENICAL POISONS. 



Arsenic in some form or other is usually the active killing agent 

 used against insects which secure their food by chewing upon the 

 foliage or fruit of plants, and since the grape root-worm beetles belong 

 to the category of chewing insects the direct killing agent (or stomach 

 poison) applied to grapevines is the arsenical poison which the spray 

 mixture contains. 



There are several forms of arsenicals used as insecticides. Those 

 that have been most commonly used in the past are Paris green and 

 arsenite of lime. Arsenite of lime is a common home-prepared 

 insecticide made by boiling together, for about 20 minutes, 1 pound 

 of white arsenic with 4 pounds of sal-soda crystals in 1 gallon of 

 water. This is known as the Kedzie formula; and when used with 

 water, milk of lime made by slaking 2 or 3 pounds of good stone lime 

 must always be added to 50 gallons of the mixture; for the boiling 

 of the sal-soda with the arsenic is simply to put all of the arsenic 

 into solution in order that all of it may unite with the lime to form 

 arsenite of lime. When used with Bordeaux mixture this addition of 

 lime is not necessary. 



Another arsenical poison and the one which has largely displaced 

 both Paris green and arsenite of lime as a stomach poison for use on 

 foliage is arsenate of lead. In properly made arsenate of lead less 

 than 1 per cent soluble arsenic is present, whereas in Paris green and 

 arsenite of lime a much higher percentage of arsenic may be soluble 

 or exist in a weakly combined state, and since it is this soluble arsenic 

 which is injurious to foliage a much higher strength of the arsenate 

 of lead can be used without danger of injuring the foliage. In 

 addition to having this advantage the lead base makes the arsenate 

 of lead much more adhesive to the foliage than either Paris green 

 or arsenite of lime. The chief element in favor of the two latter 

 arsenicals is that they are somewhat cheaper than arsenate of lead. 

 However, within the past few years the increased consumption of 



