January 21, 2010 at 8:54 a.m.

Colorado Blue Spruce not the best choice

Colorado Blue Spruce not the best choice
Colorado Blue Spruce not the best choice

I haven't completely researched it, but I believe the Haralson apple was developed in the 1930's. One of the brothers worked in plant research at the University of Minnesota and the other brother had a nursery just west of what now is the new Franconia Sculpture Park. Together they developed the Haralson apple, and they also planted the Colorado blue spruce that line our driveway, just east of the park.

Those blue spruce are now more than 30 feet tall with a branch span of several feet at the bottom. They are most beautiful after a snow with those dark green branches as the background. Their beauty prompted me to plant more Colorado spruce near the first ones, but they never turned out as well.

I found out too late that there are reasons why Colorado blue spruce don't do well in our area. Michelle Grabowski, U of M Extension Educator, suggests that one should plant Norway, Black Hills or Engelmann spruce because they are better adapted to our ever-changing winter conditions. Most trees, but especially the Colorado blue spruce, need adequate air movement around them. The property north of us has been unattended and so volunteer trees and weeds have reduced the air circulation around the spruce. I'm sure the pollution from the cars and trucks on Hwy. 95 hasn't helped either.

Colorado blue spruce are more susceptible to fungal pathogens than other conifers giving another reason for planting another variety of tree. Many needle diseases result in needle death and needle drop. Grabowski reminds gardeners that spruce needles will not grow back after being lost to fungal infections like the leaves on deciduous trees will. New needles are only produced on spruce trees once a year on the tips of branches. As a result spruce trees with a severe needle disease often appear thin or discolored. Needle retention and color is important to the trees for food production and tree vitality. Branches that have lost needles for three to four years in a row often die. If the disease is properly identified and treated before branch damage occurs, the spruce will gradually regain its needles and appear full again.

Fungal pathogens thrive in moist conditions, so gardeners can reduce the severity and the spread of many needle cast diseases by reducing moisture on the spruce needles. Use drip irrigation or direct the water at the soil and not at the canopy of the tree. If you must apply on the needles, do so in the morning so they will have all day to dry off. Don't shear spruce trees as it creates compact growth that stays wet longer. All weeds and tall grass crowding the tree should be removed to provide better air circulation around the tree. Another point that I learned too late was that young spruce should not be planted near old spruce because the old trees may be harboring fungal pathogens.

Spring must be around the corner because the garden calendars have been sent and the Chisago Soil and Water sent out their form for ordering trees. It was Soil and Water staff that made us aware back in 1998 that the Colorado blue spruce should not be ordered, but could be replaced with White, Black Hills, and Norway spruce.

Another sign of spring is that at the end of January we will be sending out information about our Spring Gardening Bonanza, plant order forms, and a schedule of our spring classes. The major change with our Bonanza this year is that it will be at the south end of the county. It will be Saturday, March 13, 2010, at Chisago Lake Lutheran Church in Center City.


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