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Sitka spruce
Coast Spruce
Yellow Spruce

Picea sitchensis

The largest spruce in the world is the Sitka Spruce. A Sitka Spruce may live for 700 – 800 years old and reach a height of 200 feet or more. Although the natural range of Sitka Spruce is a relatively narrow strip from Alaska to northern California, it may be found anywhere from 3000’ mountain heights down to seashore level.

Sitka Spruce trees near sea level in Alaska have exceeded 200 feet in height and 10 feet in diameter. The largest Sitka Spruce on record can be found in Seaside, Oregon. It is 216’ tall, almost 17’ in diameter, and has a crown spread of 93’.

Its tolerance for salt spray allows the Sitka Spruce to grow near the seashore. The summer fogs and moist maritime air also help to maintain the humid conditions that are favorable to the growth of Sitka Spruce. Trees in coastal areas also benefit from relatively mild winters, cool summers, and plentiful moisture although, once dormant the Sitka Spruce is able to withstand low temperatures without damage.

Sitka Spruce will grow best on deep, moist, well-aerated soils. It can tolerate sandy or coarse-textured soils, or soils with a thick accumulation of organic matter, as long as there is adequate drainage. Sitka Spruce will not tolerate, or will grow poorly, in swampy sites. Additionally, root decline will occur if soils become compacted or the level of aeration in the soil is altered. Ornamental Sitka Spruce can be killed if soil is added over the root zone.

The Sitka Spruce is one of the few conifers that will regrow branches along the main trunk if the trunk is exposed to sunlight. Thinning of the upper canopy, or surrounding trees, may stimulate new lower branch growth. Conversely, if shaded, lower branches die quickly and break off leaving a resinous branch stub. Ideally, these branch stubs should be pruned back to the main trunk to allow callus growth to grow over the wound.

The needles of Sitka Spruce are green, about 1” long, and pointed at the tip.

Cones are 1.5 – 3.5” long, cylindrical, with thin, irregularly toothed scales. Most Sitka Spruce tree will start producing cones when they reach 20 – 40 years of age.

 

A few insect pests on Sitka Spruce are White Pine Weevil, Spruce Aphid, and Root Collar Weevil. White Pine Weevil usually attacks Sitka Spruce trees that are 10 – 20 tall and are more common in the southern part of the range of Sitka Spruce. A natural hybrid between Sitka Spruce and White Spruce (Picea x Lutzii Little) has shown some resistance to White Pine Weevil attacks. Spruce Aphid may be found on ornamental Sitka Spruce trees from Alaska to California. Root Collar Weevil girdles, and may kill, 1 – 2 year old Sitka Spruce seedlings.

Sitka Spruce is highly susceptible to root rot if injury occurs to the main trunk. Several rust diseases can cause light to moderate defoliation.

A natural variation, known as the Golden Spruce was discovered in British Columbia. Cuttings from this tree have been developed into a cultivar named Picea Sitchensis ‘Bentham’s Sunlight’.

The natural range of Sitka Spruce is a relatively narrow strip along the Pacific coast from south-central Alaska, south into Canada, and continuing to Mendocino County, California.

Sitka Spruce characteristics:

Common insect pests of Sitka Spruce: White Pine Weevil (Pissodes strobi); Spruce Aphid (Elatobium abietinum); Root Collar Weevil (Steremnius carinatus); Spruce Beetle (Dendroctonus rufipennis)

Common disease pests of Sitka Spruce: Root rot caused by Heterobasidion annosum and Armillaria mellea. Several Rust diseases cause minor foliar problems.

Fruit: 1.5 – 3.5” long brown cones

Growth Rate: Moderate to fast

Needles: About 1” long, four-sided, pointed at the tip

Mature height: Up to 200’

Preferred soil pH: 3.9 – 5.7

Summer foliage: Green

Tree Bark: Thin, divided at the surface into thin, elliptical silvery-gray to purplish-gray scales.

USDA Hardiness Zone: 6 – 9

 

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