332 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



the emulsions. Emulsions, you know, are used for the destruction of 

 aphis, Psylla, and scale-insects. There are some hundreds of different 

 formulae which have been used. There are the paraffin emulsions in 

 which paraffin oil has been mixed with soap — what are called soap 

 emulsions. We use these very casually. We just spray the tree with 

 paraffin emulsion to kill the aphis that is coming or is there ; we do 

 not think what paraffin we are using ; there are any number of paraffins, 

 some more fatal to the tree than others, some scorch up the trees and do 

 infinitely more harm than insects can do ; but there are paraffins you can 

 use which do only a little damage. So, first of all, if we are going to 

 use paraffin emulsion, which I should certainly advise no grower to use 

 in the summer, because paraffin always damages the leaf to a certain 

 extent — but if we have to use it, for instance, if we have a very bad 

 combined attack of apple scale and apple sucker, where we have to do 

 something drastic, then use only the best oils. Without discriminating 

 particularly there are two very excellent oils. One is the Solar Distillate 

 Oil, which has an advantage over others for several reasons ; one is that 

 it is carried by the railways without bother because of its very low flash 

 point ; another is that it contains something that is very fatal to the 

 sucking-mouthed insects, and from what has been seen it has less effect 

 on the foliage of the trees than other good oils. Another kind of oil 

 which does comparatively little harm is known as White Rose Oil. I 

 need not now give you the formulae. Probably you have all got your 

 own. You will always find that if soap emulsion is left a little while a 

 certain amount of the paraffin separates from the soft soap. I do not 

 think you can get anything like perfect emulsion with soap and paraffin. 

 The metal emulsion that Mr. Pickering has discovered is very important 

 and you will find it works excellently. De-emulsification does not take 

 place with basic sulphates, as it does with soft soap, and the metal 

 emulsions can be permanently emulsified, and have just as strong killing 

 power on many aphides as where soft soap is used. There, again, we 

 have an old idea upset. I have not the slightest doubt that soft soap 

 alone is fatal to aphides, and yet you use one of these metal emulsions 

 without soft soap, and get exactly the same results. If you use an 

 emulsion with the soap you are liable to de-emulsification ; the paraffin 

 may come off too strong and do harm ; the soft soap may come out as 

 usual, and we know in the destruction of aphis it does a very large amount 

 of good. If we have certain fungi, for instance the scab, we can make 

 the metal emulsion with copper sulphate instead of with iron sulphate, 

 which one would use if dealing only with insects. We can thus combine 

 a fungicide, for instance for scab, and an insecticide, the copper sulphate 

 acting as a fungicide and emulsifier of the paraffin at the same time. 

 That I call a distinct advance, and from what has been claimed for it, 

 and what I have seen on a small scale, this emulsion will destroy certain 

 young caterpillars. Some time ago Mr. Bear, of Hailsham, found he 

 could kill sawfly on the gooseberry with ordinary paraffin emulsion. 

 Thus we may be able to simplify washing fruit trees to a very consider- 

 able extent, but I would emphasize the fact that this is only at present in 

 an experimental stage. We have not had sufficient experiments to know 

 whether caterpillars are destroyed wholesale, or to know whether it is only 



