Donald L Copes

• Effects of leader topping and branch pruning on efficiency of Douglas-fir cone harvesting with a tree shaker
• Effects of water suspension and wet-dry cycling on fertility of Douglas-fir pollen
• Rooting Sitka spruce from southeast Alaska
• Selection and propagation of highly graft-compatible Douglas-fir rootstocks, a case history
• Tree shaking machine aids cone collection in a Douglas-fir seed orchard