The Pacific Northwest (PNW) has seen increasingly dry and hot summers over the past decade resulting in high mortality rates of newly planted noble fir seedlings in Christmas tree plantations. The majority of Christmas trees grown in the PNW are dry-land produced. In late June of 2021, a prolonged period of excessive heat, referred to as a heat dome, caused temperatures to soar to record breaking highs in Washington and Oregon. Temperatures reached 118 °F (48 °C) in major Christmas tree production regions of Oregon. Past trial data indicates typical noble seedling mortality ranges 10-15%, during the first year. Many PNW growers experienced significantly higher mortality percentages in 2021. Many growers suffered 70-80% mortality and some complete crop losses.

To explore options of improving seedling survival, trials were established in March 2022 to increase survival and growth of first year noble fir (Abies procera) and Douglas-fir (Pseudotsuga menziesii) at three grower sites in the PNW. The trial is investigating three promising pre-plant treatments and wood chip mulch, which has proven to increase seedling survival in past trials at some locations. Two-year old noble and Douglas-fir seedling plugs were hand planted at all sites. Pre-plant treatments include: 1. Mix of, Puric Prime 1-0-2, Nutrio Unlock, Till-It Blue Zone Max 6-24-6, Tricoderma Ecto mycorrhizae, 2. Nucleus 0-0-21-13 and O-Phos, 3. Best Paks 20- 10-5. Post-planting treatment: Wood chip mulch applied 2 inch depth (5 cm) in a 12 inch (30 cm) circle around tree. A non-treated control is included for comparison. Height measurements at initial planting, mid-season and at conclusion of trial are planned. Air temperature and tree bio-mass data will be collected throughout the growing period. Seedling mortality and root volume evaluations are planned after fall rains begin in October 2022.