The disease begins in the lower portion of the tree with infected needles being shed, causing branches to look sparse. Stigmina needle cast is often mistaken for Rhizosphaera needle cast. Rhizosphaera needle cast is a common foliar disease of spruces and other conifers caused by the fungus Rhizosphaera kalkhoffii. Spore dispersal from infected needles occurs during wet weather in spring, spreading by rain from needles infected the previous season to newly emerging needles. Spruce in both urban and rural landscapes can be affected. Healthy spruce will retain its needles for five to seven years. The most common disease of blue spruce is Rhizosphaera needle cast, a fungal disease that usually requires fungicides for management when it occurs. Early detection and proper diagnosis is important in the treatment of… Stigmina needle cast is a fungal disease of spruce trees caused by the pathogen Stigmina lautii. Rhizosphaera needlecast is a fungal disease affecting mainly Colorado spruce, and occasionally other spruce. Rhizosphaera needle cast (caused by the fungus Rhizosphaera kalkhoffii) primarily infects Colorado blue spruce, while Stigmina needle cast (caused by the fungus Stigmina lautii) affects both blue spruce and Black Hills spruce. Rhizosphaera needle cast is the most common disease on spruce trees, including Colorado blue spruce, white spruce, Oriental spruce, and occasionally the Norway spruce and red spruce. Norway, black, blue, and white spruce are hosts to this pathogen. 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 … With age, spruces become a "shell" - a support structure for needles out on the ends of branches only. Spruce trees can show brown needles starting from the lower limbs and progressing up the tree. Blue spruce varieties are very susceptible to Rhizosphaera. Colorado blue spruce is particularly susceptible and can be severly damaged by this disease. Colorado blue spruce needles do have a finite life - 8 to 10 years, then they drop. Rhizosphaera needle cast causes needles to turn purplish brown and fall from the tree, usually from the inside of the tree working out and from the bottom of the tree working up. Microscopic observation is required to distinguish both diseases from each other. The recent pattern of milder than usual winters and cool spring temperatures combined with wet conditions in the northeast have favored development of a fungal disease known as "needle cast". Some spruce trees, such as Colorado Blue Spruce may be susceptible to environmental stress. Needle cast diseases thrive in humid, wet environments and they are more common in the north and east parts of our state. So every year you can expect to see about 1/10 - 1/8 of the innermost/oldest needles turn yellowish, then brown and drop. Spruce infected with Rhizosphaera needle cast may only hold the current year’s needles. One common needle disease in Minnesota, Rhizosphaera needle cast, is caused by the fungus Rhizosphaera kalkhoffii.