DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 49 



Potatoes. Dusting potatoes with calcium arsenate for the control of 

 the Colorado potato beetle has given excellent results. Such work can 

 be done with an of chard duster and without any special outlet for dis- 

 tributing the material to each row. If there is much work of this 

 kind to be done, it would probably be better to secure a special attach- 

 ment. 



DRY LIME-SULPHURS AND B. T. S. 



The dry lime-sulphurs and B. T. S. have not given satisfactory control 

 of apple scab so they cannot be recommended for the summer spraying 

 of apples as a substitute for lime-sulphur solution. 



Xo experiments have been conducted with this material for the con- 

 trol of San Jose scale as it has not been possible to find enough live 

 scale during 1918 and 1919 for reliable tests of this kind. 



ARSEXICALS 



Lead arsenate is recommended for general use on all kinds of fruits. 

 It has given uniformly better results than any other arsenate. 



Calcium arsenate has given excellent results when used on potatoes 

 and other similar crops, but has not always given satisfactory results 

 when used on fruit trees. 



Magnesium arsenate has caused severe foliage injury on peaches and 

 apples and has failed to give satisfactory control of codling moth. This 

 material probably will not give such unsatisfactory results in every in- 

 stance but since there is danger of injury from its use it is not recom- 

 mended at this time.* 



*This material at this time is manufactured in a form which is supposed to be non-injurious 

 to foliage. It cannot, however, be recommended without further tests. 



