Fig. 12: Well-shaped tree (L.) and foliage (above) of Douglas-fir.
Douglas-fir is not a true fir. It is native to a wide geographic area in the West and Canada, and considerable genetic variation exists in the species (Fig. 12). Seedlings grown from seed collected on the West Coast are generally not winter-hardy in Ohio. Those from high elevations in the northern Rocky Mountains usually grow very slowly and are often damaged by late spring frosts after growth begins in early spring.
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Fig. 12: Well-shaped tree (L.) and foliage (above) of Douglas-fir. |
Seedlings raised from seed collected in southern Colorado, Arizona and New Mexico seem best for planting in Ohio. These include seed sources from the Coconino, Lincoln, Santa Fe, San Juan, San Isabel and Kaibab National Forests. These sources produce trees having good growth rates and relatively long needles borne singly along the twigs and usually have bluish or blue-green foliage. They also break bud somewhat later in the spring; thus, they are less subject to late spring frost damage.
Of those species commonly recommended for planting in Ohio, Douglas-fir is probably the most difficult species to grow successfully for Christmas trees. It prefers cool, moist, well drained sites with moderate to high fertility. It does not tolerate either excessive moisture or drought. Tight, fine textured soils, dry soils and dry ridges and slopes should be avoided as planting sites. Late spring frost injury is a major problem. The species should preferably be planted on cool, north and east facing slopes where there is good air drainage. The basic conical form of the species is good, but shearing is usually necessary to produce high quality Christmas trees. Needle retention on cut trees is excellent. About 7 to 11 years are needed to produce 6 to 7-foot trees on good sites. Gall aphids and Rhabdocline needle cast are the major pests affecting Douglas-fir.
In summary, of the several species that could be planted for Christmas trees in Ohio, five are recommended for general planting in the state: Scotch pine, white pine, Colorado spruce, Fraser fir and Douglas-fir. Scotch pine, adapted to a wide range of sites, has been by far the most widely planted species. However, because of continuing insect and disease problems and lower wholesale and retail prices, planting of Scotch pine has declined in recent years. Conversely, planting of white pine, also adaptable to a fairly wide range of sites, has been increasing steadily. Similarly, plantings of the more site- demanding Colorado spruce, Fraser fir and Douglas-fir have increased, although acreage in these species is still relatively low. The other three species discussed in detail in previous sections are not recommended for general planting. Needle shed on cut trees is the major problem with Norway and white spruces, while frost damage and irregular growth are the major problems with balsam fir.