Colorado blue spruce is the primary host. Read about the IPM Program. Watch for white smut on Gaillardia plants. Healthy needles have white stomates. Pest management guides for ornamental pests available. For canker diseases, the effectiveness of fungicides is usually limited.

Additional suspects have been identified. Our clay soils are good for sugar maples, but difficult for the roots of spruces to penetrate and thrive in. Rhizosphaera needle cast is common and widespread in Michigan, and the fungus attacks needles during the growing season in spring. Later, the needles turn brown to purplish brown. Spruce spider mites cause needle discoloration and eventually kill needles, which can be mistaken for a needlecast disease Photo 7. Improve air circulation through pruning and proper plant spacing.

For insect or mite issues, insecticides or miticides can be effective, however selection of the proper product and timing are critical.

Product Q&A

Spruce spider mites cause needle discoloration and eventually kill needles, which can be mistaken for a needlecast disease Photo 7. Infected needles first appear mottled or speckled with small yellowish spots. Frost-covered plants caught on video. There are a number of factors contributing to the decline we see in blue spruce trees, including environmental changes, poor site conditions and new pathogens. Most commonly fungicides used in the landscape only act as prophylactics.

Prolonged exposure to moisture and trees that are crowded are most subject to fungal infection.

Another complicating factor is that trees may be healthy for a number of years and then begin to decline as they mature and are more difficult and costly to remove. Eventually, the infected spruce needles turn a brownish to purplish color.

For more information, visit http: This is a difficult question. Apply three or more fungicide treatments starting in the spring rhizosphaea protect new growth. Pest management guides for ornamental pests available. Just remember to keep a mindful eye on your spruce trees. To determine if your trees rhizosphera chemical management, look for signs of fungal fruiting bodies on the needles.


Typical symptoms of cankers are sunken areas along a stem that may ooze resin Photo 5. Read about the IPM Program.

Blue spruce needle cast disease – MSU Extension

Because Stigmina is so new, we still do not know much about this fungus, but we do know what controls Rhizosphaera. Left, Decline symptoms moving upward. However, in some plantations needle casting symptoms still micihgan after sprays Photos 1 and 2. The likelihood of having success can be improved by planting blue spruce trees on sites with conditions they favor. Spraying specimen trees in spring may help contain this pathogen, but no studies have yet been conducted to test this.

These specks nwedle the spores that spread the disease throughout the tree. Check the label of any pesticide referenced to ensure your use is included.

Some of rhizodphaera diseases are familiar: March 26, – Author: Full control may not be achieved in one growing season because of nedle length of time infected needles remain on the tree. Repeated treatments are necessary to make meaningful improvements, and it may take several years to see the improvement.

Pictures courtesy of www. In fact, it is not uncommon to see healthy, thriving spruce trees near or adjacent to trees that are in severe decline. Blue spruce sustains the greatest damage, but we are also noticing damage to Colorado, Norway and White spruce. Colorado blue spruce trees have long been among the most popular conifers for landscaping in Michigan and the upper Midwest.

The Sad Story of Spruce Trees in Michigan – Green Street Tree Care

As a result, they are stressed and more susceptible to fungal pathogens. The rapid decline of many spruce trees in Michigan and surrounding states appears to be related to an increase of canker diseases coupled with other disease and insect problems that plague the species. Diseases old and new: Proper watering is essential to avoid stressing the tree by either over watering or causing drought.


Finally, for decades the default diagnosis for most problems with blue spruce has been Rhizosphaera needlecast or Cytospora branch canker. Left, Gall caused by Cooley spruce adelgid.

Colorado blue spruce is the primary host. Print a PDF of this page: Trimming off the infected branches back to the trunk will reduce inoculum and slow the spread of the disease. Usually the lower branches are first to die, but sometimes the disease begins in the upper crown or at multiple points.

Diplodia and Phomopsis are both considered weak or secondary pathogens, so it is unclear at this point why they appear to cause major disease problems for spruce. Rhizosphaera needle cast is common and widespread in Michigan, and the fungus attacks needles during the growing season in spring.

Norway spruce is resistant. rhizospgaera

Decline usually starts on lower branches. Eventually, the spruce needles turn a brown or purple color and drop from the tree.

Three rhizosohaera more fungicide treatments in the spring and throughout the summer will help protect newly emerging spruce needles.

Essentially there are no spruces native to southeast Michigan. A menace in chestnut orchards. We still do not know for sure if this fungus is completely responsible for these symptoms after spraying for Rhizosphaera. Previously infected needles will continue to be lost even after fungicide treatments have begun, and infected needles may remain on the tree for up to 15 months. It may be necessary to continue the disease prevention program for up to five years to fully control the disease while the tree’s vigor is regained.