New York Agricultural Experimext Station. 301 



possible to determine whether the specimens found had survived 

 the fumigation. 



Under folding fumigators. — Five hundred and fifty tests were 

 made during the winter of 1900-1901. At time of treatment 

 many of these trees were infested. Only one was found where 

 there was positive proof that the scale had survived the 

 fumigation; this was a peach treated March 19th (a windy day), 

 with four-fifths ounce of potassium cyanide per 100 cu. ft. (.25 

 gram per cu. ft.) for 35 minutes. On August 26th, it was found 

 that the lower branches which lay close to the ground were 

 badly infested with living specimens. Adjoining trees showed 

 a few living scales on December 7th. These were not badly 

 infested trees before treatment, and the specimens were found 

 only on sides next the previously infested tree showing quite 

 conclusively that they became infested from it. 



In only one other instance has any trace of living scale shown 

 itself as lato as December 7th." This was on a tree which was 

 slightly if at all infested before fumigated. Only three speci- 

 mens were found. All indications are that this tree became 

 infested after treatment, possibly from the previously mentioned 

 tree, although about ten rods to the north of the latter. 



As shown in the discussion of diffusion, it is possible that 

 hydrocyanic acid gas was absorbed by the moist ground rapidly 

 enough so that individual scales on the lower branches survived 

 the treatment, but if this was the case similar results ought to 

 have been obtained from some of the other 181 tests made on 

 peach with same amounts of cyanide of potassium, even though 

 all the trees were not infested at time of treatment. It seems 

 more probable that an accident during fumigation of this one 

 tree must have occurred. Either the wind caused the fumigator 

 to lift frequently during the period of exposure, or an error was 

 made in the amount of chemicals used. 



Before drawing conclusions it should be stated that the plums 

 found infested after treatment were fumigated after the tents 

 were much the worse for wear and badly in need of reoiling. 

 In fact, at time of treatment of this small orchard there was 



