135 



affect the setting of the fruit to any material extent in the case of the 

 peach, and not at all in the case of the apple. 



' The experiments, as a whole, indicate the vastly superior merit of 

 the soap wash and its fall application. The greater vigour of the plant 

 resulting from the fall treatment more than offsets the possible failing 

 of bloom. Owing to the impossibility of controlling weather conditions 

 and the practical difficulty of wetting every part of the plant, one spray- 

 ing cannot often be relied on to accomplish the death of all the scales, 

 but two conscientious drenchings may bo expected to accomplish this 

 result. These may bo (1) at the time of, or shortly after, the falling of 

 the foliage in autumn, and (2) just before blooming in spring.' 



Other soaps (hard laundry soap) are efficacious, but not to the same 

 degree. 



In another of the American reports * is an instructive paper on in- 

 secticide soaps, by Mr. 0. L. Marlatt, from which 1 take the liberty of 

 quoting largely : — ' The decided insecticide value of the so-called whale 

 oil (more properly fish oil) soaps, against scale insects particularly, has 

 been fully demonstrated in the last few years in the work against the 

 San Jose scale, and has fully substantiated Professor Comstock's early 

 recommendation of this means of controlling scale-insect pests. The 

 merit of these soaps is not only in their effectiveness as insect destroyers 

 but from their being entirely without injurious effect on the treated 

 plant. In this respect they are perfectly safe in the hands of any 

 person, in contradistinction to all oily washes, which are very liable 

 to be injurious in greater or less degree, although the in- 

 jury may be insignificant, or perhaps not apparent immediately, 

 or during the first season.' .... 4 The use of soaps is 

 attended with certain difficulties.' .... 4 To be satisfactory for insec- 

 ticide use it must, when dissolved at the desired rate, say two pounds 

 to the gallon of water, remain a liquid capable of being sprayed 

 with an ordinary nozzle at an ordinary temperature. This may 

 be determined by a very simple test and one which should be invariably 

 given any soap before it is accepted for spraying operations. It con- 

 sists in simply dissolving a, small quantity of the soap at the desired rate, 

 and allowing it to cool.' 



Many soaps solidify or become gelatinous and tenacious on cooling 

 These are useless for spraying purposes. The common country soap of 

 Ceylon has this defect. I have experimented in a small way with soap 

 mixtures; but it is difficult to obtain here a brand that combines suitabil- 

 ity with cheapness. Such a brand is a great desideratum. I find that 

 one of the most useful properties of th9 soap mixtures is to prevent the 

 escape of the young larvae by blocking up the natural exits, and on this 

 account the treatment is to be very strongly recommended. 



Kerosene Emulsion — Soap is often combined with other ingredi- 

 ents. Of these kerosene emulsion is the best known and most widely 

 used. As its efficacy and its effect upon plant lite very greatly de- 



* U. S. Department of Agriculture (Division of Entomology). Bulletin 

 No. 6 (New Series.) 



