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Caring for Spruce and Other Trees

County Agent News
Dan Folske
May 22, 2017

Caring for Spruce and Other Trees

     Have you had disease problems in your trees? The spruce trees are losing their bud caps and the new needles are emerging. Spruce TreeThat means it is time to spray with a fungicide if you are concerned about spruce needlecast. If the needles from two years ago are brownish red and falling off and some of last years’ needles are also turning brown your tree may have an infection of needlecast disease. The problem with this disease and many other fungal diseases is that by the time you see the symptoms it is too late to do anything about it. You can however, protect the new needles from becoming infected. Spraying the new needles with a protective fungicide can prevent them from becoming infected. Multipurpose fungicides approved for ornamental use like chlorothalinol and daconil can be sprayed onto the new needles protecting them from becoming infected. This treatment should be repeated in about ten days to two weeks. Another product which can also be effective is a mixture of copper sulfate and lime often called a Bordeau mixture.    

     Another concern for spruce trees at this time is the yellow headed spruce sawfly. This fly lays its eggs on the emerging needles where its larvae will have a tender food source as they hatch and grow. The tiny larvae are difficult to see because they are perfectly color matched to the new needles. I find it is easier to spot the damage than the worms. Look carefully for needles that have been shortened by chewing or which are turning pink or brown partway along the needle. You will often find small clusters of needles which are turning a pink tint and also curling because the tiny worm has taken a bite out of several different needles and damaged but not consumed them.             

     Remember that the stem of the new growth is the same color as the new needles so the new growth can still look green from a distance. I often get calls in august about spruce trees turning brown. At that time the stem of the new growth is turning and it becomes easy to see that the needles are gone but it is far too late to do anything except wait until next year and hope the tree can recover.

     The apple trees and many other fruit trees are blossoming now and this is the time to spray a fungicide to prevent diseases like apple scab and plum pockets disease. Any fungicide approved for fruit trees can be used.

           

 

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