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University of Illinois Extension

Spruce Needle Diseases

by Jim Schuster retired University of Illinois State Extension Educator - Horticulture & Plant Pathology

Stigmina needle cast compared to Rhizosphaerea needle cast and Sudden needle drop (Setomelanomma)

 

Stigmina needle cast

Rhizosphaera needle cast

Sudden needle drop

Symptoms

Needles turn purplish-brown and fall off from the inside out & from the bottom of the tree up. Small black, spider-like od furry looking fruiting structures develop in rows (emerge through the stomata which are in rows). The needles look dirtier than Rhizosphaera infected needles since fruiting bodies look like little spiders. No white waxy cap pushed out with the fruiting body can be seen with magnification

Needles turn purplish-brown and fall off from the inside out & from the bottom of the tree up. Small black, smooth, round fruiting bodies develop in rows (emerge through the stomata which are in rows).
Fruiting bodies look like smooth bowling balls. Often, a white waxy cap that has been pushed out with the fruiting body can be seen with magnification.

Yellowing and eventual browning of older needles. Affected branches may be scattered through the canopy. Frequently, by autumn, all of the needles on the affected branches fall off except the newest needles on the tips of the branches. Eventually the canopy of the tree thins, sometimes leaving bare branches. Black fruiting bodies are on the stems.

Host(s)

Colorado spruce (P. pungens), Norway spruce (P. abies), black spruce (P. mariana), white spruce (P. glauca).

Primarily on Colorado spruce, & occasionally Black Hills spruce (P. glauca var. densata).

Colorado spruce, Norway spruce and white spruce including Black Hills

Fruiting Structure

sporodochia

pycnidia

pseudothecia

Family

Incertae sedis

Incertae sedis

Phaeosphaeriaceae

Genus

Stigmina

Rhizosphaera

Setomelanomma

Pathogen

???

Yes

???

Known distribution at this time

Canada, Michigan, North Dakota, North Carolina, & Illinois

Canada, Kansas, Minnesota, Wisconsin, Iowa, Michigan, & Illinois

France, Canada, Kansas, Iowa, Missouri, Michigan, Minnesota & Illinois

Fungicide management available

None known

Yes -spray 2years in a row, 2X’s each year (as bud caps fall off & full grown)

Seems to be - but none label


Filed under plants: Evergreen Trees & Shrubs

More information is available on Hort Answers.