The fungus is spread by splashing and dripping water beginning in spring and continuing into the fall. Severe repeated infections can cause branch mortality. You can also get this publication at the extension office in Logan. Rhizosphaera needle cast is a fungal disease, caused by Rhizosphaera kalkhoffii that attacks the needles of Colorado blue spruce in the spring, as new needles emerge. Young trees may be killed by this disease, but usually branches die off after 3-4 consecutive years of defoliation, causing trees to look disfigured. The fight against rhizosphaera needle cast. Other hosts include white, black, Engelmann, Sitka, and Serbian spruce; Austrian, mugo, Eastern white, and Japanese red and black pine, as well as Douglas-fir and Siberian fir. Newly emerging needles can become infected during wet spring weather. In addition to fungicide sprays, other control measures include spacing trees adequately to promote good air circulation, improving tree vigor through mulching and watering when needed, and not shearing trees when the foliage is wet. Another needle disease with similar symptoms that we’re seeing quite a bit of this year is Stigmina needle cast. As a result, they are stressed and more susceptible to fungal pathogens. Also, another prevention strategy for landowners to use is to prune the lower branches of their spruce. The most common canker disease observed in the Iowa State University Plant Disease Clinic is Cytospora canker on blue spruce. Policies | Blue spruce trees are susceptible to an infectious needle disease caused by the fungus Rhizosphaera. Symptoms - The disease is usually first evident on lower branches and then works upward gradually. Colorado blue spruce is particularly susceptible and can be severly damaged by this disease. He estimated his crews have taken out over 500 blue spruce trees in recent years due to fungal diseases known as needlecasts. Al: Why does this seem to be such a problem this year? *We will never send you spam or share your info. Scout declining trees closely for cankers. The disease, referred to as Rhizosphaera needle cast, is the most common problem seen on blue spruce samples that are submitted to the Plant Disease Clinic. For Staff | State & National Extension Partners | Pruning the lower branches off will allow better air flow under the tree and dry off the needles more quickly after rain or dew events. var path = 'hr' + 'ef' + '='; White spruce are classified as intermediate in susceptibility to the disease and Norway spruce are relatively resistant. An accurate diagnosis is important, since some diseases cannot be effectively treated and some can. var addy329dab251343736a54bc869a40f25fa4 = 'kretz' + '@'; Plant trees in a good site, one that is well-drained and allows unrestricted growth as the tree matures. (Fruiting structures of the fungus are not evident on these trees.). In general, trees appear to die from the bottom upward. Linda: It causes the tree to drop needles prematurely. Any cultural practice that promotes good tree vigor helps prevent canker diseases. At least 2 years of treatment will be necessary to allow trees to begin to recover their full complement of needles. By: Al Koeppel, Kretz Lumber Company, with insight from Linda Williams, Wisconsin Department of Natural Resources. piceae) , is the most prevalent and destructive fungal disease of Norway and Colorado blue spruce. Inconspicuous cankers develop on lower branches—the cankers girdle the branches causing resin to flow out of the cankers and drip down the trunk of the tree. Needle cast diseases thrive in humid, wet environments and they are more common in the north and east parts of our state. Prune at least 4-6 inches below any visible cankers. Prevention is important if control is desired. Spread - Rhizosphaera over winters in infected needles on the tree and on needles that have fallen to the ground. Norway spruce, blue spruce and white spruce are among the most popular trees in the area, prized for their winter color and ability to screen out the neighbors. Complete coverage of the needles is important to protect them. Norway spruce, blue spruce and white spruce are among the most popular trees in the area, prized for their winter color and ability to screen out the neighbors. Once infected, the lower branches of the tree turn brown, which results in needle loss. 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