356 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



It is necessary here to precipitate the iron, which can be ascertained 

 by testing the clear liquid (before the paraffin is added) with potassium 

 ferrocyanide ; if a Prussian blue coloration is seen more lime is required. 



Uses. — The first acts both as a fungicide and insecticide, the second as 

 an insecticide only. Aphides, leaf-hoppers, and thrips are destroyed by 

 this wash, and, according to Mr. Spencer Pickering, caterpillars are also 

 killed by it. 



Time of Application. — Just when the buds are bursting, and again 

 when the blossom has fallen. Arsenate of Lead may be mixed with 

 either of these washes. 



Apply as a fine spray. 



Quassia and Soap Wash. 



Formula : 



Quassia chips 10 gallons. 



Soft soap . ^ lb- 

 Water 10 gallons. 



Preparation. — Boil the quassia chips in water for a couple of hours, 

 then dissolve the soap in warm water, if possible, and mix the strained off 

 quassia extract with the soap. Another method of preparation consists 

 of boiling the quassia with half the soap and half the water ; strain off the 

 liquid, and boil the residue for one hour with the rest of the soap and 

 water, and mix the two decoctions and make up to 10 gallons of water. 



Uses. — For the destruction of all aphides and Psylla. 



Time of Application. — As soon as the aphides hatch from their eggs 

 or appear on the plants, if migrants. 



Tobacco Wash. 



Formula : 



(1) Tobacco powder 

 Soft soap . 

 Water 



(2) Tobacco leaf 

 Soap . 

 Water 



3 lb. 

 Jib. 



10 gallons. 



i lb. 



1 



10 gallons. 



Preparation. — Infuse the tobacco powder or leaf in water for about 

 six hours, then strain off and press the tobacco and infuse again. Add 

 the tobacco extract to the dissolved soft soap and water. 



Uses. — An excellent insecticide for aphis, Psylla, cuckoo-spit insects, 

 leaf hoppers, and thrips. It is also to some extent a repellant or 

 ins. ctifuge, and for this purpose may be sprayed over unopened or 

 opened blossom, with the hope that it may prevent egg-laying by pear 

 midge and apple sawfly. No results, however, have yet been con- 

 clusively obtained in this matter. It may be procured in the form of 

 a powder-tobacco, which has been denatured in bond, at 20s. per cwt., 

 or if the leaf is used any of the coarser tobaccos will do at about 

 3.s. 6(7. per lb. If powder is employed a much greater quantity is 

 necessary than if the leaf, but the former, being so much cheaper, is 



