Silviculture and Swiss needle cast : research and recommendations

For the past ten years, Douglas-fir on the Oregon and Washington\ud coast has shown a progressive decrease in height and diameter increment\ud as a result of Swiss needle cast, which is caused by\ud Phaeocryptopus gaeumannii. In this contribution, we discuss the\ud effects of silvicultural operations on Swiss needle cast and recommend\ud specific actions to reduce the severity of the disease. We also\ud suggest a method of assessing the severity of Swiss needle cast damage\ud to a stand based on years of needle retention. Our recommendations\ud are based on disease severity and are designed to discriminate\ud against Douglas-fir when planting, thinning, and harvesting\ud stands suffering low, medium, and high Swiss needle cast severity.\ud These recommendations are based on our collective observations\ud and research being conducted by the Swiss Needle Cast Cooperative