DISCUSSION OF PAPERS. 47 



Mr. Quaintance called attention to some tests of various arsenicals 

 on peach foliage made by the Bureau of Entomology during 1906, 

 and stated that all arsenicals used — as arsenate of lead (homemade) 

 and the principal proprietary brands, Paris green and Scheele's 

 green — were injurious either to the foliage or fruit. A new insecti- 

 cide arsenical was tested, namely, arsenic sulphid, which was stated 

 by chemists to be quite insoluble. Nevertheless this proves to be 

 more injurious than any of the other arsenicals used — in fact, killing 

 several of the trees outright. 



Mr. Webster recalled the fact that in 1888, while in Tasmania, he 

 found the pear mite and also a species of fungus in connection with 

 it. Dr. J. C. Arthur had told him that this fungus was always asso- 

 ciated with this particular mite. 



Mr. Parrott stated that the attack of these mites on foliage was 

 sometimes mistaken for the pear scab fungus (Venturia pirina 

 Aderh.). 



Mr. Taylor remarked that arsenate of lead was being used to a con- 

 siderable extent in Colorado. During the past year 16 carloads had 

 been applied with good results. He had used it on peach trees for 

 the twig borer {Anarsia lineatella Zell.) and found that it worked 

 satisfactorily. It can be used on these trees if it carries no free 

 arsenic. In some cases the branches had been killed by burning. 

 This trouble is usually indicated by the appearance of purple spots 

 on the young wood. The rainfall in this section is 7 inches per year, 

 and this may have some bearing on the effect of poison on the foliage. 



Mr. Slingerland called attention to the use of Scalecide and other 

 miscible oils. He stated that in an orchard badly infested with Asp- 

 idiotus perniciosus that had come under his observation excellent 

 results had been secured when scalecide was applied. 



Mr. Burgess remarked that he had used Scalecide and Kil-o-scale 

 on a badly infested apple orchard last spring. The manufacturer's 

 directions required the mixing of 1 gallon of these materials to *20 

 gallons of water. Tests were made using 1 gallon to W 14. L9, and '24 

 gallons of water. Satisfactory results were secured when Kil-o-scale 

 was used at the rate of 1 gallon to 14 gallons of water, but when 

 Scalecide was used at the rate of 1 gallon to ( .) gallons of water the 

 San Jose scale was simply held in check. 



Mr. J. B. Smith stated that the difference in these two substances 

 was not very great, although the Kil-o-scale carried more sulphur and 

 5 per cent less actual petroleum. 



A general discussion of the subject followed, which was participated 

 in by Messrs. Brooks, Taylor, Slingerland, J. B. Smith, Fernald, 

 Quaintance, Britton, and others. This brought out the fact that 

 variable results had been secured with these substances, as far as 



