Have all the  older needles on your spruce trees falling off? Your tree may have Rhizosphaera Needlecast disease. This disease has become prevalent on North Dakota spruce trees during the last several years. It attacks the spruce needles in late spring and early summer when the weather is cool and wet.

Needles which become infected this spring will not show symptoms until next spring. The needles which were infected last year will turn a dark reddish-brown color this spring and then fall off the tree next year. Since it takes a year for the symptoms to appear, infected branch tips will appear a healthy green and the entire branch will remain pliable. Needlecast develops first on the lower branches of the tree but in severe cases may spread up the whole tree.

Control of Rhizosphaera Needlecast depends on the application of a protective fungicide when the new growth is ½ to 2 inches long, followed by a second application in three to four weeks. Either Bordeaux or Chlorothalonil (sold as Daconil 2787 or Bravo) is available for control. Application of these fungicides at other times of the year will NOT prevent needlecast infection. In the case of larger trees, you may need special equipment for good needle coverage. Since the cost of treatment is expensive be sure that the problem is correctly identified before treating.

This page was last updated May 2003

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