Fungal fruiting bodies appear as two rows of black dots on the undersides of the needles, along either side of midrib. I estimate about 6 to 7 percent of the needles shed on all the trees. Symptoms & Signs. Young trees sustain the most severe damage, but trees of any size can be affected. This combination of fungicides help to reduce the chance that certain strains of fungi become resistant to treatment. Hello, There are several fungal issues and diseases that Colorado blue spruce trees can develop over time that will result with needle loss and dead branches, Rhizospera needle cast is just one of them. The fungal pathogen, Rhizosphaera kalkhoffii, is responsible for needle cast of spruce species.This disease has been detrimental to Christmas tree plantations, especially those in eastern U.S.A., and to spruce trees in nurseries and landscapes outside of their native range. PowerPoint presentation, 4.1 MB. Penn State Cooperative Extension does not endorse specific companies. Infected needles, including those that are still attached to branches and those that have fallen to the ground, produce spores that can be blown or splashed to healthy branches or trees. Rhizosphaera needle cast is a fungal disease of spruce trees that causes needles to turn brown and fall off. Repeated infection will cause branch dieback. ... and a systemic fungicide called propiconazole. It affected about two thirds of the trees and needles sluffed was from 5 percent to 33 percent with it not being very uniform. Rhizosphaera needle cast is a foliar disease that occurs worldwide on a diverse range of conifers. Needle cast disease, caused by the fungus . Trees stressed from drought, poor planting practices or other factors are more likely to suffer from Rhizosphaera needle cast. This PowerPoint is provided for its technical content. Rhizospaera Needle Cast (RNC) is a fungal disease that causes needle cast and premature death of needles in conifer trees. Colorado and Engelmann spruce are very susceptible, but Norway and white spruce are somewhat resistant. sp., results in purple to brown discoloration of scattered needles and eventual needle cast (needle drop) (Figure 1). Trees can be protected from Rhizosphaera needle cast with properly timed fungicide applications. Needle Cast Diseases of Douglass fir Swiss Needle Cast of Douglas Fir. The summer before last my Black Hills Spruce had a needle cast disease and shed quite a few needles. One and two-year-old infected needles turn from yellow to brown or appear mottled in late winter. Where does Rhizosphaera needle cast come from? Needle Cast . Rhizosphaera needle cast is caused by the fungus Rhizosphaera kalkhoffii. Rhizosphaera needle cast disease is caused by the fungus Rhizosphaera kalkhoffii Bubak. Symptoms develop on older needles and on lowermost branches first, and then progress upward. Rhizosphaera.