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The loss of activity of pyrethrum. II

Published online by Cambridge University Press:  27 March 2009

F. Tattersfield  and
J. T. Martin
F. Tattersfield
Affiliation:
(Department of Insecticides and Fungicides, Rothamsted Experimental Station, Harpenden, Herts.)
J. T. Martin
Affiliation:
(Department of Insecticides and Fungicides, Rothamsted Experimental Station, Harpenden, Herts.)
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Summary

1. The loss of activity of pyrethrum flowers and preparations has been studied.

2. The degree of concordance between the content of pyrethrin I, as determined by the acid method, and the insecticidal value of pyrethrinised dusts, before and after exposure to air and artificial illumination, has been statistically examined. The pyrethrin I values, corrected for a small residual amount of extraneous matter, indicate fairly closely the degree of activity of the samples. The loss of pyrethrins on exposure has been traced out quantitatively.

3. A comparison was made between two samples of pyrethrum flowers, one rich and the other poor in pyrethrins, in order to determine the degree of concordance between the pyrethrin I content and their toxicity. The pyrethrin I value as determined by the acid method, subject to a small correction, gave a good indication of the relative activities of the samples.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 24 , Issue 4 , October 1934 , pp. 598 - 626
Copyright
Copyright © Cambridge University Press 1934

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References

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