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ESTIMATING MITE POPULATIONS IN SOUTHERN OREGON PEAR ORCHARDS1

Published online by Cambridge University Press:  31 May 2012

P. H. Westigard  and
L. D. Calvin
P. H. Westigard
Affiliation:
Oregon State University
L. D. Calvin
Affiliation:
Oregon State University
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Abstract

Studies were conducted in southern Oregon pear orchards to develop sampling methods for assessment of mite abundance. Those species included in the investigation were the two-spotted spider mite, Tetranychus urticae Koch; European red mite, Panonychus ulmi (Koch); yellow spider mite, Eotetranychus carpini borealis (Ewing); and the predaceous phytoseiid Typhlodromus occidentalis Nesbitt.The results show that five leaves on one limb per tree are adequate to include representative numbers of the four mite species. Variation in mite densities between trees, even of the same variety, was quite high. The sample size (numbers of trees) required for assessing mite density can be calculated provided that an estimate of the coefficient of variation (S/X) is available.

Type
Articles
Information
The Canadian Entomologist , Volume 103 , Issue 1 , January 1971 , pp. 67 - 71
Copyright
Copyright © Entomological Society of Canada 1971

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References

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