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Fielding Questions: An ailing spruce, adding ashes to soil and more

Don Kinzler

Q: I was shocked to see our 40-year-old spruce has developed patches of brown, dead needles. Since it's an established tree and it was a wet fall, I didn't water it. Is this caused by lack of moisture, disease or is this tree nearing the end of its life? — Kay Hogetvedt, Felton, Minn.

A: The spruce very likely had adequate moisture this fall. Because several needle cast fungal diseases have been prevalent on the region’s spruce, I asked retired North Dakota State University plant pathologist Jim Walla for his opinion. “It doesn’t appear the tree is dying although the needles have thinned, resulting in the tree not looking as nice as it could," Walla says. "New shoots grew this year, and as long as those remain alive at the ends of the shoots, the tree has potential to regain a thicker and greener appearance.

“The pattern of thinning and browning could be caused by needle cast disease. Send a sample to a diagnostic lab next spring to check. The other common cause of thinning and browning is reduced availability of nitrogen. If there isn’t significant needle cast, then supplementing with nitrogen fertilizer would likely result in gradual improvement in tree health and appearance.”

Q: Are fireplace ashes good fertilizer for the sandy soil in the Minnesota lakes area? Or is the soil naturally high enough in this component? — Erik Holten, Fargo.

A: Similar questions arose 36 years ago while I was with the Extension Service, as the 1980s saw an increase in the use of wood-burning stoves and fireplaces. In response, a soil specialist and I prepared a bulletin, long out of circulation, about the use of wood ashes.

From the bulletin: “Although wood ashes contain nutrients like phosphorous and magnesium, they are high in lime (calcium) and should not be used in large quantities on area soils, most of which are alkaline and already very high in calcium. One inch of ashes applied to the soil surface is a relatively safe application rate. Repeated application of wood ash could result in accumulation of salts or calcium to cause toxicity, especially on heavy textured, poorly drained clay soils.”

More recent information from Oregon State University cautions against using any ash on alkaline soil, and most of the soils in North Dakota and western Minnesota are alkaline. You might test your soil, as wood ash can benefit the acid soils more commonly found in eastern and southern United States.

Q: The bark on two of my 5-year-old oak trees is being eaten by woodpeckers. Does something need to done, or isn’t this an issue? — Jerry Luebke, Fargo.

A: The photos you sent show areas of bark have been stripped away on the trunks of the young oaks. Woodpeckers often make a series of holes in tree trunks in search of insects. They also pry away strips of bark as they look for insects that are tunneling or wintering under the bark.

When bark is torn away from large trunk areas, the tree or certain branches can be killed. Unfortunately, there are no curative products or pruning sealers that are effective for repairing areas already damaged. Time will tell whether the depth of the damage causes serious injury.

To prevent further injury from woodpeckers, wrap the trunks with burlap or apply gooey Tanglefoot bird repellent.

If you have a gardening or lawn care question, email Don Kinzler at ForumGrowingTogether@hotmail.com. All questions will be answered, and those with broad appeal may be published, so please include your name, city and state for appropriate advice.