338 NEW YORK STATE MUSEUM 



moist and distinctly visible for several months, and this residuum undoubt- 

 edly interferes with the establishment of young scale insects. The spray- 

 ing should be done when the bark is dry. It must be very thorough, and, 

 in places where the scales have formed incrustations, it is quite difficult 

 to kill all the insects even with this substance. The best method in a 

 large orchard is to spray at two different times, working always on the 

 windward of the trees and .spraying the second half when the wind is 

 from the opposite direction to that from which it was when the first half 

 was sprayed. A 10 foot brass extension with two to four cyclone nozzles 

 is almost necessary for the best results. W. H. Hart, of Poughkeepsie, 

 prefers to have the nozzles connected with the extension by a small 

 piece of pipe bent at an angle of about 45° from the line of the extension. 

 Some prefer the nozzles set at a right angle to the extension. It is better 

 to have them turned somewhat, and the precise angle is apt to vary with 

 individual preferences. Trees sprayed with crude petroleum or kerosene 

 should not be trimmed previous to the apphcation as the cuts afford an 

 opportunity for the oil to enter and kill the twig for a short distance. 

 Experiments with this mechanical emulsion on the allied species of 

 A spidiotus are advised. 



Crude petroleum undiluted. Experiments with this undiluted 

 crude oil showed it to be very injurious to plant life, killing two out of four 

 trees and seriously injuring the others. The effects of an application of 

 this undiluted crude petroleum to plumtrees is strikingly shown on plate 

 8. The lombard plumtree 93 was sprayed with this substance April 11. 

 Compare its appearance on July 2 with that of tree 8, one of the same 

 variety, which was sprayed April 11 with a 20% mechanical kerosene 

 emulsion. A little later in the season tree 93 died. Plate 9 shows the 

 effect of crude petroleum on seckel peartree loi. Note the dead linibs and 

 contrast this with the illustration of the Kieffer peartree no, which was 

 sprayed on the same date as the others but with Good's whale oil soap no. 3. 

 It is a pleasure to record that this latter tree fulfilled the promise of its 

 bloom. The photograph taken at Kinderhook May 21 of a King apple- 

 tree, which was painted with crude petroleum Dec. i, 1899, apparently 

 shows that this substance is more deadly if the application be made in 

 early winter. This tree died during the summer. At present the use of 

 the undiluted article can not be recommended as safe in New York state. 

 Dr Smith states in a recent bulletin that he has found that crude petroleum 

 which ran above 43° on the Beaum6oil scale did not injure the trees, that 

 below 40° was liable to cause serious injury, while the oil giving a reading of 



