CHAPTER XV 

 Contact Insecticides — For Sucking Insects 



Lime-sulphur Solution 



Lime sulphur is a chemical combination of lime and sulphur, and 

 kills insects by its caustic properties. At the same time it has con- 

 siderable value as a fungicide, for the control of such plant diseases as 

 apple scab. 



The material is used both as a winter spray, when the trees are dor- 

 mant, and as a summer spray, the latter for fungus diseases ; but the 

 solution for summer use is much weaker. Material of the proper 

 strength for winter use must never be sprayed on trees in leaf as it 

 will burn the foliage. 



The best time to apply the winter strength of lime-sulphur solution 

 is in the early spring, just before the buds swell. For San Jose scale 

 and for leaf blister mite, two insects for which this material is especially 

 useful, this is the most effective season. It may be applied in the fall, 

 however, at any time after the leaves drop. 



There are three ways of preparing the winter wash of lime sulphur : 

 by diluting the commercial concentrated solution now on sale in stores 

 to the required strength; by making a concentrated solution at home, 

 and properly diluting when needed ; and by making at home a solution 

 which w^hen finished is ready at once for use. These will be described 

 in order. 



Commercial Lime Sulphur 



Commercial concentrated lime sulphur is a clear, reddish brown liq- 

 uid. It has been placed on the market by a number of manufacturers, 

 and is obtainable practically everywhere. 



For use, this material simply is diluted with water. The amount of 

 water to be added always is indicated on the container in which the 

 hquid comes. But if it is desired to test the strength, this can be done 



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