Origin
Picea glauca (Moench) Voss var. densata Bailey is a variant of the white spruce, commonly found in Canada and northern parts of the United States.
Common Names
This variant of the white spruce is commonly known as the black hills spruce, Densa spruce or Picea glauca ‘Densata’. The name 'Densa' is derived from the plant's dense habit.
Appearance
The Densa spruce is a slow growing, conical evergreen tree with a dense habit. It has a symmetrical form, with a straight trunk and a narrow crown. The branches are slender and slightly curved upwards. The needles are blue-green to gray-green in color and are approximately 1 inch long. The buds are light brown and particularly resinous.
Uses
The Densa spruce is commonly used for ornamental and landscaping purposes due to its dense and symmetrical growth habit. It is also a valuable timber tree, used for paper pulp, lumber, and other wood products. The needles of the plant are sometimes used in tea and as a source of vitamin C.
Light Requirements
Picea glauca var. densata prefers full sun to partial shade to grow and thrive. It can tolerate shady conditions for a brief period, but it may affect the tree's growth and overall health. To ensure proper growth, the tree should receive at least six hours of direct sunlight daily.
Temperature Requirements
The Picea glauca var. densata is hardy and can tolerate cold weather and harsh winter conditions. Generally, it grows well in areas where temperature ranges from -40 to 20 degrees Celsius (-40 to 68 degrees Fahrenheit). However, the tree may not thrive in hot and humid conditions, making it unsuitable for regions with temperatures above 30 degrees Celsius (86 degrees Fahrenheit).
Soil Requirements
The Picea glauca var. densata grows well in well-drained, moist, and loamy soils with a pH level ranging from 5.0 to 7.0. The tree does not tolerate acidic soil and may struggle to grow in heavy or poorly drained soils. Adequate soil preparation and proper drainage are essential for the tree's optimal growth.
Cultivation
Picea glauca (Moench) Voss var. densata Bailey prefers growing in a location with full sun to partial shade. It can excel in different soil types, but soil that is well-draining, moist, and slightly acidic is recommended for optimal growth and development.
In terms of temperature, this plant can tolerate cold and frosty conditions but should be protected from extreme heat and drought.
Watering Needs
Picea glauca (Moench) Voss var. densata Bailey requires an adequate amount of water to grow. Young trees need more frequent watering than mature ones. However, it is crucial to avoid over-watering since excessive moisture can lead to root rot. The best way to keep the plant adequately watered is to use a moisture meter to monitor moisture levels and water the plant only when the soil becomes relatively dry.
Fertilization
Picea glauca (Moench) Voss var. densata Bailey benefits from regular fertilization to support healthy growth and development. It is recommended to fertilize the plant in the growing season, spring to summer when the plant is actively growing. A balanced fertilizer with a 10-10-10 ratio of nitrogen, phosphorus, and potassium should be used. Be sure to follow the manufacturer's instructions for proper application, frequency, and amount of fertilizer.
Pruning
Pruning Picea glauca (Moench) Voss var. densata Bailey should only be done to remove dead, damaged, or diseased branches. Pruning should be done during the spring or early fall when the tree is dormant. To avoid harming the plant, only remove up to one-quarter of the tree's branches in a single season. Avoid cutting too close to the branch collar, which could lead to further damage or disease.
Propagation Methods for Picea glauca (Moench) Voss var. densata Bailey
Propagation of Picea glauca (Moench) Voss var. densata Bailey can be done through several methods including seeds, cuttings, and grafting.
Propagation by Seeds
Seeds can be collected from the cones of mature trees during the fall season once they have ripened. After collecting the seeds, they should be cleaned and stored in a cool, dry place until the spring planting season. Prior to planting, it is recommended to soak the seeds in water for 24 hours to promote germination. The seeds can then be planted in a well-draining soil mix and kept moist until they have germinated.
Propagation by Cuttings
Softwood cuttings can be taken from new growth on the tree during the summer season. Cuttings should be taken from healthy trees and should be at least six inches in length. Remove the needles from the bottom half of the cutting and dip it in rooting hormone before placing it in a well-draining soil mix. Keep the soil moist and the cutting in a bright, but not direct sunlight until new growth appears.
Propagation by Grafting
Grafting can be used to propagate Picea glauca (Moench) Voss var. densata Bailey onto a rootstock of a related species. This method is usually done by professional growers and requires skill and experience. The graft should be done during the dormant season and careful attention should be given to ensure that the graft is successful.
Disease and Pest Management for Picea Glauca var. Densata
Picea glauca var. densata, commonly known as the Rocky Mountain White Spruce or the Alberta White Spruce, is a coniferous tree with blue-green needles and a dense pyramidal shape. Due to its hardiness, it is popular in landscaping and as a windbreak. However, like all plants, it is vulnerable to diseases and pests. Proper disease and pest management is crucial to keep the trees healthy and looking their best.
Common Diseases
The most common diseases that affect Picea glauca var. densata are needle cast and canker diseases.
Needle Cast: Needle cast is a fungal disease that causes the needles to turn brown and fall off. This disease is often caused by excessive moisture, poor air circulation, and overcrowding. Prevention techniques include proper spacing and pruning to promote air circulation, avoiding overhead watering, and removing infected needles.
Canker Diseases: Canker diseases are caused by fungal or bacterial infections. They cause sunken areas on the trunk or branches of the tree, and can eventually kill the tree if left untreated. Prevention techniques include avoiding mechanical damage to the tree, properly pruning and disposing of infected branches, and applying fungicides.
Common Pests
The most common pests that affect Picea glauca var. densata are spider mites, spruce budworm, and sawflies.
Spider Mites: Spider mites are tiny pests that suck the sap from the needles and cause them to turn yellow and fall off. They are common in dry conditions. Prevention techniques include regular watering to keep the tree healthy, avoiding the use of broad-spectrum insecticides, and releasing natural predators like ladybugs.
Spruce Budworm: Spruce budworms are caterpillars that eat the needles and can defoliate the entire tree. Prevention techniques include releasing natural predators like parasitic wasps, properly pruning and disposing of infected branches, and applying insecticides.
Sawflies: Sawflies are small, non-stinging wasps that lay their eggs on the needles of the tree. The larvae feed on the needles and can defoliate the entire tree. Prevention techniques include releasing natural predators like birds and parasitic wasps, properly pruning and disposing of infected branches, and applying insecticides.
Conclusion
Proper disease and pest management is essential to keep Picea glauca var. densata healthy and looking its best. Prevention techniques like proper spacing, pruning, and regular watering are key to preventing diseases and infestations. When necessary, applying fungicides or insecticides can help control the spread of diseases and pests.
