92 



barium, sodium and potassium. Certain results of tests con- 

 ducted by Prof. Parrott with these various compounds are 

 given below. 



Efficiency and Cost of Sulfur Compounds 



Only a glance at the figures is necessary to show that 

 the old reliable lime-sulfur wash is a little more efficient and 

 decidedly cheaper than the other compounds. It was found 

 in these experiments that sodium and barium compounds 

 lacked uniformity, while the sodium and potassium prepara- 

 tions were apt to burn the foliage very badly when applied 

 as summer sprays. The Federal insecticide law compels all 

 insecticides entering Interstate commerce to bear on eacn 

 and every package, a label giving the percentage of the 

 essential ingredients, and it is therefore very easy to judge 

 correctly as to the value of the sulfur compounds, if com- 

 parison is made with the above table. By all means pur- 

 chase insecticides on the basis of the efficient content. Mere 

 pounds count for nothing unless you have the real thing in 

 the package. With this table, so far as sulfur compounds 

 are concerned, one can easily judge as to which is the best for 

 average orchard spraying. The Baume or specific gravity 

 test is the most reliable indication of the relative value of 

 lime-sulfur washes. A high grade concentrated lime-sulfur 

 wash, commercial or home-made, should contain practically 

 no sediment. 



A miscible oil is sometimes used in the place of a lime- 

 sulfur wash for the control of San Jose scale and blister 

 mite. This, either home-made or commercial, is not entirely 

 safe, owing to the fact that under certain climatic condi- 

 tions or the physiological state of the tree, serious injury 

 may result. Such a preparation appeals to many, however, 

 because it spreads more readily than a lime-sulfur wash. 



In view of the great abundance of San Jose scale 

 parasites, the question may arise as to the probable need of 

 spraying in sections where these insects are numerous. There 



