372 KEPORT OF THE COMMISSIONER OF AGRICULTURE. 



possible importance as a remedy, those who have access to natural 

 springs or who now use flowing wells of sulphur water for the purpose 

 oil irrigation, should thoroughly test it by making repeated applications 

 at short intervals. 



Kerosene.— Emulsions containing GG per cent, of kerosene oil, and 

 diluted with water ten times, as in applications for scale-insects, do not 

 kill the eggs of the Rust-ini{e. The same emulsions diluted one to 

 twenty, kill nearly all the mites, but do not kill the eggs. With dilu- 

 tions of one to forty, many adults escape destruction. In all the ex- 

 periments made with kerosene upon scale insect the trees were not 

 cleared of Rust-inites. They usually reappeared in numbers, within 

 rive or six days, owing to the hatching of the eggs. As a remedy for 

 Rust-mite, therefore, kerosene is not as effective as either whale oil soap 

 or sulphur. 



In making applications for scale-insect it is advisable to render the 

 wash effective against Rust-mite also, and this can be in a measure ae- 

 accomplished by adding sulphur. 



Experience has shown whale-oil soap to be superior to condensed milk 

 iu forming emulsions, and much cheaper. Emulsions made with soap 

 do not thicken or ferment, as when milk is used. 



The formula that has already been published (see ante, page 331) 

 gives the best results. 



The emulsion should be dilu-ted with water ten times, or in the pro- 

 portions 1 to 9, and applied in line spray. 



Iu cases where an application is needed for both scale-insect and 

 Rust-mite the above wash, with two or three ounces of sulphur added 

 to each gallon of the mixture, forms the most effective combination 

 that can at present be devised. It is best applied in early spring, but 

 should never be used in midwinter or when there is danger from frost. 



Creosote. — Several experiments with crude oil of creosote, saponified 

 with lard oil and lye, or dissolved in strongly alkaline solutions, gave 

 about the same results as 6G per cent, kerosene emulsions. The mites 

 were readily killed, but their eggs for the most part survived. 



Creosote is highly poisonous to plants, and must be used in small 

 doses. Four or five fluid ounces of crude oil of creosote, dissolved in 

 one gallon of stroug soap solution, makes as strong a wash as it is safe to 

 apply. Although even cheaper than kerosene, it is not a more effective 

 remedy, and, owing to the greater danger attending its use, it cannot 

 be recommended in preference to the latter. 



A strong carbolic or creosote soap can be purchased at a reasonable 

 price, and will prove ver}- useful to orange-growers, as it is not only a 

 powerful insecticide, but also a remedy for " die-back, 7 ' and possibly also 

 for " foot-rot," or any disease of the plant of fungoid origin. 



Potash. — Very strong lye is required to 1 ill tho mites, and their eggs 

 are not destroyed except by solutions sufficiently caustic to burn the 

 leaves and bark. 



The different commercial brands of concentrated lye and caustic 

 potash vary greatly iu purity and strength. The potash used in the 

 following experiments was a superior article, put up in 1-pound balls, 

 coated with rosin : 



(1.) Solution: 4 pounds (48 ounces) potash to 1 gallon water. Leaves 

 dipped in this solution were badly burned, and, together with them, the 

 mites and eggs were entirely destroyed. 



(2.) Solution: 2 pounds (24 ounces) potash to 1 gallon water. Leaves 

 charred. Mites and eggs destroyed. 



