Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is a non-native conifer from western North America that was introduced into European forests at the end of the 19th century. Plantations of Douglas-fir in Europe have shown good performance, quality, and resilience to exacerbating climatic conditions. However, all these qualities strongly depend on provenance. A total of 1061 surviving trees of fifteen different Douglas-fir provenances were measured in a Slovenian provenance trial that was established within the framework of the 1966/1967 IUFRO seed collection program. We found significant differences among provenances with respect to survival rate, growth performance, and log quality. The total recorded yield of the 46-year-old stand was 602.9 m³/ha, and the average survival rate was 43%. The correlation of juvenile tree heights in 1985 and their average breast height diameters in 2017 is positive and significant. Based on vitality and diameter, the best performing provenances were Yelm and Cathlamet. The provenance with the best log quality assessed through branchiness is Jefferson (Olympic Peninsula, western Washington). All the most promising provenances for western Slovenia (Central Europe) originate from the low-altitude western coast of Washington (WACO), with the Cathlamet provenance showing the best combination of good growth, survival rate, and log quality.

Pests and diseases together with harmful abiotic factors present a serious problem for the production of healthy and vital forest tree seedlings. In order to examine the most important and most frequently occurring harmful abiotic and biotic factors, we analyzed the annual reports of health surveys from 18 forest nurseries in the period 1997-2018. The results revealed that the observed injuries were caused by pathogenic fungi in 68 % of cases, insects in 29 % of cases and abiotic factors in 1.1 % cases. Injuries occurred on 45 different tree and shrub genera, with Quercus sp. and Pinus sp. being the most frequently damaged (24.1 % and 17.5 %, respectively). Damage was frequently observed on leaves or needles (64.0 %). The most commonly reported diseases were powdery mildews (Erysiphe sp.). The greatest variability in the number of pests and diseases appeared on pines (Pinus sp.). Damage to planting stock usually occurred at low intensity (up to 10 %) but varied considerably during the period. The production of quality and healthy planting stock requires a holistic approach to seedling care.