468 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 14 



the dust remains on the foHage for a sufficient length of time after appli- 

 cation in order to destroy the young mites as they hatch from the eggs. 

 In combining the lime sulphur solution at the rate of one gallon of 

 the stock solution to fifty gallons of water with the nicotine sulphate 

 40% solution at the rate of one gallon to nine hundred gallons in the 

 diluted lime sulphur solution, this combination proved an excellent 

 spray in killing the red spiders, thrips, and leaf hoppers. The lime 

 sulphur solution in this combination proved effective over as long a 

 time as did the lime sulphur alone against the red spiders on the trees. 

 Examination of the check plot showed the red spiders, thrips and leaf 

 hoppers alive. 



Comparative Cost of Spraying and Dusting 



During the time the comparative experiments were made a few 

 figures were taken on the cost of the different dusting and sprayiiig 

 materials employed, and the time required to dust and spray 100 average 

 avocado trees nine years of age. 



Comparative Cost of Spraying and Dusting 



Conclusions 



1. The dusting method with dry sulphur was found to be equally as 

 effective in controlling red spiders on avocado trees over as long a 

 period of time as the spraying method with liquid lime sulphur 

 solution. 



2. The experiments proved that it is not necessar^^ that the foliage of 

 the avocado be wet with dew in order that the dr}' dusting sulphur 

 be effective. 



3. Sulphur in any of the combinations used did not control leaf thrips 

 or leaf hoppers, and nicotine sulphate 40% solution when used alone 

 or combined with either lime sulphur solution or dry dusting sulphur 

 will destroy them. 



