EXPERIMEXT STATION EEPORT. 579 



l)le. oil in preference. Pear trees, unless verv badlv infested (and 

 the same is true of plums), will do very well with the lime and 

 sulphur combinations, but pear trees seem on the whole to derive 

 as e^-eat a tonic effect from the oil as the peaches do from the Kme 

 and sulphur, and therefore I advise the former if only one kind of 

 material is to be used. Apples should have at least one spraying 

 T\'ith O'il to reach the scales near the tips, which are so guarded that 

 they stand more than an even chance of escape from even two ap- 

 plications of the lime and sulphur washes, and if one kind of ma- 

 terial only is to be used, I advise the oil. 



IS'o oil combination that contains less than 4 per cent, of actual 

 petroleum in the spraying mixture can l>e depended upon, and upon 

 that basis ''Scalecide," "Kill-O-Scale'' and similar combinations, 

 which are really liquid petroleum soaps, should be used at the rate 

 of 1 to 15 as a minimum strength. Those mixtures that are said 

 to be emulsions, and for which a greater percentage of actual oil is 

 claimed, should be used at a similar dilution, even though this may 

 give a slightly greater percentage of oil, because, for some reason 

 which is obscure to me, emulsions are not so effective as the "solu- 

 ble" oils. The K.-L., properly made and applied, is equal in effect 

 to the soluble oils when it contains 15 per cent, of actual oil, and 

 the same is true of the mechanical mixtures of oil and water. 



The litoe washes cannot be satisfactorily used on trees that have 

 been treated with undiluted crude oil or with a mechanical mix- 

 ture containing a large percentage of crude oil, because the vaseline 

 remnant on the surface prevents a proper adhesion ; but they may 

 be used after the soluble oils because these contain no vaseline 

 remnants, and wash oft" or evaporate comjiletely. 



Rain within twenty-four hours after spraying is apt to interfere 

 with the effect of any mixture except undiluted crude oil, but the 

 lime and sulphur combinations rarely suffer much after they are 

 once set. 



Thoroughness of application is essential whatever is used, and 

 there should always l)e force enough to drive the spray into every 

 crevice and through the hairy covering of twigs, and this is espe- 

 cially true of the lime washes, which tend to form a coating over 

 a crevice or depression, instead of penetrating into it. 



