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Spots, Bands and Browning on Conifers

Michelle Grabowski, UMN Extension Educator

M.Grabowski, UMN Extension

Photo 1: Dothistroma Needle Blight on Mugo Pine

A wide variety of fungal diseases have been reported on pines, spruce and junipers this spring. Fungal needle blights may start out as a spot. As the infection continues the spot grows into a band that completely encircles the needle. Eventually all of the needle tissue beyond the infection dies, resulting in needles that are green at the base and brown at the tip. In other infections, the entire needle or the entire shoot is killed and turns brown.

It is important for gardeners to identify exactly what fungus is causing the problem on their conifer before attempting to control the disease. Each fungus infects different parts of the plant at a specific time of year. Control practices must be precisely timed in order to be effective.

M. Grabowski, UMN Extension

Photo 2: Kabatina Tip Blight on Juniper

The University of Minnesota Extension webpage has an online diagnostic tool called 'What's wrong with my plant?' that helps gardeners identify the pest that is affecting their tree. The diagnostic tool contains photos and descriptions of common pest problems in Minnesota. For each pest problem a link for more information will take the gardener to a publication with more information about pest biology and management options.
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