Impact of Swiss Needle Cast on Postharvest Hydration and Needle Retention of Douglas-Fir Christmas Trees. G. A. Chastagner, Western Washington Research and Extension Center, Washington State University, Puyallup 98371. R. S. Byther, Western Washington Research and Extension Center, Washington State University, Puyallup 98371, J. D. MacDonald, University of California, Davis 95616, and E. Michaels, Western Washington Research and Extension Center, Washington State University, Puyallup 98371. Plant Dis. 68:192-195. Accepted for publication 25 August 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-192.

Healthy Douglas-fir (Pseudotsuga menziesii) Christmas trees were compared with those infected by Phaeocryptopus gaeumannii for needle loss and dehydration after cutting. The presence of infected needles increased the rate of dehydration (as measured by changes in xylem water potential) of cut trees placed in water or left dry. Fungicide applications made 1 yr before harvest significantly improved retention of 1-yr-old needles on trees displayed either wet or dry, whereas applications during the year of harvest made no difference in retention of either current-season or 1-yr-old needles.