New York Agricultural Experiment Station. 425 



In 1911 Dr. J. B. Smith 3 stated "experience has shown that a 

 winter spray of miscible oil, diluted not over ten times, and applied 

 with force enough to penetrate to the bottom of all crevices, produces 

 satisfactory results. I usually recommend that the rough bark be 

 first removed; but if that is done, it is essential that the spraying 

 be done immediately thereafter, and that the scrapings be either 

 burnt at once or thoroughly drenched with the spray. The insects 

 become active enough to crawl at a very moderate temperature, 

 and if scrapings are left lying during an entire sunny day, they may 

 leave them and get among the soil rubbish for a new shelter. On 

 the other hand, the sprayings should not be done at a temperature 

 at or below the freezing point as that impairs the efficiency of 

 the oil." 



The eggs of the pear psylla have usually been regarded as quite 

 resistant to sprays which are considered " safe to foliage." Experi- 

 ments by Slingerland 4 in 1892 with various insecticides such as 

 kerosene emulsion used full strength, or diluted in three parts of 

 water heated to 130° F., pure kerosene, turpentine emulsion at a 

 dilution of one part of the emulsion to three parts of water, pure 

 turpentine, crude carbolic acid emulsion diluted with ten parts of 

 water, resin wash used triple strength, and heated to 130° F., whale- 

 oil soap and sulphide of potash wash used at double strengths, 

 concentrated potash in the proportion of one pound to one gallon 

 of water, or benzine in undiluted sprays, led him to conclude that it 

 is inadvisable to attempt to combat the pest by spraying to kill 

 the eggs. Subsequent experiments by Marlatt 5 in 1894 with various 

 oil-emulsions were more successful, but as a varying percentage of 

 the eggs were unharmed he also laid chief emphasis on the importance 

 of destroying the newly hatched nymphs as the most reliable method 

 of control. 



With the general use of the lime-sulphur sprays in the East, com- 

 mencing about 1902, there have been indications that applications 

 of these mixtures have proven of more or less value in the prevention 

 of injuries by this pest. In 1904 6 some experiments by this Station 

 indicated that these washes had afforded considerable protection 



3 N. J. Agr. Expt. Sta. Rpt. 31:305-6. 1910 (1911). 



'Cornell Univ. Expt. Sta. Bui. 44:179. 1892. 



"Insect Life. 7:183-4. 1894. 



•N. Y. State Agr. Expt. Sta. Bui. 262:62-63; 65-6. 1905. 



