EXPERIMENT STATION BULLETINS. 271 



POTASSIUM SULPHIDE. 



Potafs.siiim Sulphide (liver of sulphur) .... 3 ounces 

 Water 10 gallons 



This solution is valuable for the gooseberry and other powdery mil- 

 dews, for which it seems even more effectual than Bordeaux mixture, 

 although its effects are less lasting. It does not discolor the fruit and 

 is quite harmless. 



KEROSENE EMULSION. 



This is a well-known remedy for use upon soft-bodied or scale insects 

 that suck the sa]). It is made from kerosene, water and soap, either 

 hard or soft, or whale oil. 



To one quart of water add one pint of soft or two ounces of hard 

 soap and heat until the soap is dissolved. Add one pint of kerosene 

 and agitate freely for from three to five minutes, or until it forms a 

 cream-like emulsion, from which the oil does not separate upon stand- 

 ing. This is a stock solution and can be kept for any length of time. 

 Before using, it should be diluted according to the condition of the trees 

 and kinds of insects. For scale insects it is desirable to spray while the 

 trees are dormant, after diluting this stock solution so that there will be 

 one part of kerosene to three of water, but if it is applied for the same 

 class of insects wliile the trees are in leaf, the amount of water should be 

 at least seven or eight times as great as of the kerosene in the stock solu- 

 tion. At this strength it will be fatal to all soft-bodied insects and to 

 many of the scales, while for many of the insects with soft bodies it 

 will be found sufficiently powerful if fifteen parts of water are used to 

 one of the kerosene. 



When making the emulsion with whale oil soap, the amount of the soap 

 will vary with the amount of water it contains. If in a semi-liquid con- 

 dition, one pint will answer for a pint of the oil, while four ounces will 

 be sufficient if it is in a solid form. 



In making the emulsion care should be taken to keep the kerosene away 

 from the fire, and a force pump should be used rather than to rely upon 

 a spoon or paddle. 



SOLUBLE OILS. 



The various "soluble" oils that are being sold for the control of the 

 San Jose scale have been carefully tested, but while they kill a very 

 large per cent of this insect, owing to the rapidity with which it breeds, 

 the trees will be more thickly infested at the end of the season than 

 before they were sprayed. Aside from being ineffectual against the 

 scale at the strengths recommended, these remedies are quite expensive 

 and have no fungicidal value. By using them three or four times as 

 strong as recommended by the manufacturers their efficiency will be in- 

 creased, but this will make their cost several times that of lime and 

 sulphur, and, unless very carefulh^ used, injury may be done to the trees. 



