INSECTS AND DISEASES 53 



somewhat. The dust form is more frequently 

 used out of doors, the material being dusted directly 

 upon the plants and the insects found thereon. 

 Various tobacco solutions are upon the market and 

 are used in the form of spray, especially when large 

 plants must be treated. Directions for dilution are 

 to be found on the packages of every brand and 

 should be carefully followed. 



Under some conditions soap solutions are to be 

 preferred over all others for certain kinds of suck- 

 ing insects. If used upon dormant plants the soap 

 is used at the rate of from one to two pounds to a 

 gallon of water. If used on growing plants the 

 soap is used at the rate of one pound to three to 

 five gallons of water. Any soap will answer the 

 purpose, but the various fish oil soaps are more 

 commonly used, hence the common name whale oil 

 soap solution. 



Lime and sulphur as an insecticide for sucking 

 insects is widely used in two forms. First, what 

 might be called the homemade, where the lime and 

 sulphur are cooked or boiled together under home 

 conditions making the dark brown liquid com- 

 monly known as lime and sulphur. The com- 

 mon formula for preparation under these con- 

 ditions is 15 pounds sulphur and 20 pounds lime 

 boiled for one hour in a convenient quantity of water 

 and diluted to 50 gallons. This is now ready to 

 apply to dormant plants, but is entirely too strong 

 for growing plants. On account of the variable 

 composition of homemade lime and sulphur no de- 

 pendable rate of dilution can be given for use on 

 the growing plants. In order to use it safely under 

 these conditions, the hydrometer test must be em- 

 ployed for each lot as it is applied. A specific 



