subject: Beware of the Blue Spruce diseases [print this page] Blue Spruce also commonly known as Colorado Blue Spruce or Picea Pungens is a tree belonging to the Picea genus. The tree grows in high altitudes and is commonly found growing near the streams in mountain valleys. It is a mid-size tree that stays evergreen all thorough the year. The average height of a tree would be somewhere around 25-30 meters and the bark is generally thin and peeling. The young trees start with a conic crown that gradually takes a cylindrical shape as the tree matures.
These trees have needle-like leaves having several stomata lines and a sharp tip. They have pendulous and cylindrical cones that mature in 5-7 months after the pollination. The tree is admired for its ornamental use. However, like all plants the tree is susceptible to a number of diseases. For its proper care and healthy growth it is advisable to be knowledgeable about the Blue Spruce Diseases and ways to combat it.
Cytospora Canker of Spruce is the most commonly disease that affects Blue Spruce trees. This disease is dominant in trees planted at poor sites, diseased trees, weaker trees, stressed trees, trees under environmental duress like freezing temperatures, drought or extreme heat etc.
The first symptom of a Blue Spruce tree affected by Cytospora Canker is that they exhibit scattered branch dieback that usually begins from the lower branches. If you observe the dead branches closely you would notice a whitish sticky sap that is produced by the trees as a reaction to being infected by the Cytospora Canker fungus. This fungus makes its entry to the tree via cracks, twigs, branches, wounds etc of the tree and over a period of time it infects the girdles of the branches causing them to ultimately die. You would also observe that the dead branches had brown needles.
For Cytospora Canker fungus the best policy is prevention as fungicides would not be able to help you much. The Blue Spruce trees should be planted in clean surrounding with well aerated soil and not too many trees crowding the space. Regular pruning during dry weather can stop the infection at the initial stages too.
Rhizosphaera Needle Cast is another Blue Spruce disease that is quite common. This is basically a fungal infection of the needle-like leaves of the tree. This infection also initially infects the lower branches and gradually spreads to the whole tree. The first symptom is purplish or brownish needles that fall off leaving behind bare branches. If observed closely you would find small blackish spots on the infected needles. Winters and wet spring weathers provide the ideal temperature and atmosphere for spreading this fungal infection.
The best treatment is a generous spray of a good fungicide all over the tree during the second week of May and a repeat spray after about four weeks. Apart from this you need to give your trees lots of space to grow; avoid planting them too close. Maintain the trees with regular mulching and proper watering. Avoid shearing the trees when the foliage is still wet. These preventive measures would go a long way in protecting spread of Blue Spruce diseases.
