New York Agricultural Experiment Station. 345 



SOME REFERENCES TO MOISTURE AND TEMPERATURE 



IN FUMIGATION. 



Lowe and Parrott 1 found in their fumigation experiments for the 

 San Jose scale that the strength of gas uniformly effective during the 

 spring, namely, .18 gram potassium cyanide per cubic foot, was 

 wholly ineffective when the tests were made during the winter. 

 Johnson 2 calls attention to some of the effects of temperature and 

 moisture in fumigation. He especially mentions the increased 

 injury to the plant when fumigations are made at high temperatures. 

 He also states that, in the fumigation of nursery stock, the plants 

 should be dry previous to treatment. 3 In speaking of the prepara- 

 tion of the greenhouse he says: " The room should not be fumigated 

 immediately after the plants have been sprinkled or watered." 4 

 Townsend 5 has shown that the presence of moisture is very important 

 in the fumigation of seeds. In his tests moist seeds absorbed the 

 cyanide gas which injured the germinating qualities and rendered it 

 unfit for food; while the dry seed was unaffected. Hinds and Turner 6 

 in a series of experiments with the rice weevil (Calandra oryza L.) 

 found that carbon di-sulphide at the rate of 5 lbs. per 1000 cubic feet 

 was effective when the work was clone at a temperature above 70° F., 

 while fumigation work done at temperatures ranging below 60° 

 appeared to be largely ineffective. The moisture factor was taken 

 into account in these experiments, but Hinds says " we have not 

 found as yet that moisture has anywhere near the same importance 

 as temperature ". 



In connection with the fumigation of citrus fruits in California, it 

 has been generally assumed that if the work is carried on while the 

 trees are damp injury to the foliage may follow. Penny 7 found in his 

 studies that moisture on the leaves absorbed gas during the fumiga- 

 tion, though Gossard 8 , Morrill 9 and Woglum 10 assert that the presence 

 of moisture on the foliage is not important as affecting the results. 



1 N. Y. Agr. Exp. Sta. Bui. 202, p. 20G. 1901. 



2 Fumigation Methods, New York. 1902. 



3 L. c, p. 120. 



4 L. c, p. 128. 



B Md. Agr. Exp. Sta. Bui. 75. 1901. L. c, p. 177. 



6 Jour. Econ. Ent. 3:47. 1910. 



7 Del. Agr. Exp. Sta. 12th Kept., p. 212-237. 1900. 



8 Fla. Agr. Exp. Sta. Bui. 67, p. G4S. 1903. 



9 U. S. Dept. Agr. Ent. Bui. 76:12-14. 190S. 



10 U. S. Dept. Agr. Ent. Bui. 90:08-69. 1911. 



