Effects of leader topping and branch pruning on efficiency of Douglas-fir cone harvesting with a tree shaker Copes, Donald L. creator Pacific Northwest Forest and Range Experiment Station (Portland, Or.) contributor text book [Portland, Or.] U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station [1985] 1985
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ENG Caption title. Distributed to depository libraries in microfiche. "October 1985." Conifers Douglas fir Harvesting Pruning Seeds Research note PNW, 431 https://www.biodiversitylibrary.org/bibliography/70764 14046734 10.5962/bhl.title.70764 GPO