R. R. Mason
Published: 2018-01-13
Total Pages: 26
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Excerpt from Forecasting Outbreaks of the Douglas-Fir Tussock Moth From Lower Crown Cocoon Samples A sample plot was 50 randomly selected host trees having lower branches within reach from the ground with the trees distributed over 2 to 5 acres to ha). Plots were selected for the study and sampled for cocoons only if they were expected to have measurable larval populations the next summer. Cocoons were sampled in the fall after moth emergence and oviposition. First and second instars were sampled on the same plots the following June. Densities were estimated in each plot by the frequency of occurrence of tussock moth (that is, cocoons in the fall or larvae in the summer) on the lower branches of 50 host trees (mason 1977, 1979, With this method for sampling cocoons, the underside of three 18-inch (45-cm) branch tips in the lower crown was visually examined on each tree for the presence or absence of cocoons. The proportion, -p, of infested sample trees on the plot was then converted to density of cocoons/1000 square inches m2) of branch area, X, by the theoretical distribution of the Poisson series (mason 1977) where. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.