Minnesota Tree Care Advisors

Characteristics
Disease Management

Black spruce also called bog spruce is hardy native tree throughout Minnesota, but more prevalent in the cooler coniferous forests and bogs of Central and Northeastern Minnesota. White and black spruce are commonly harvested for use in the pulp industries.

Small to mediumn tree height:		25-30'

Canopy spreads:		Narrow, Pyramidal crown

Spruces bear single needles that are typically 4-sided or square-ish in cross-section. The needles will roll between your fingers. Typically, the needles are pointed at the end - compare the sharply pointed needles of Colorado blue spruce to the dull or blunt points of white spruce and black spruce. Needle length on the black spruce is rather short in comparison to Colorado blue spruce and white spruce with the length typically 1/4 to 5/8 inches long.

The twigs on black spruce are reddish brown and look closely at the twigs to see the scattered hairs (compare to the hairless white spruce) with rough needle scars and the buds are typically golden brown with overlapping 'extended' scale tips. Black spruce bears its winged seeds in egg-shaped cones that are roughly 1/2 to 1 1/4 inches long. The cones are constructed of overlapping scales and the margins on black spruce cone scales are irregular.

Look for flaky to scaly bark that is reddish brown to gray in color.

Black spruce is typically not considered a good choice for hot, dry urban landscapes.

Did you know
Ever heard of "Spruce Gum?" Lumps of sap formed on the trunks of some spruce trees - early lumber men would collect these to be chewed, not exactly a common practice today. However, surely you have heard of "Spruce beer!" Well, the needles and twigs of black spruce are the inspiration and source of flavor for this drinkable concoction...

DISEASE		SYMPTOMS	MANAGEMENT
Cytospora canker, Leucostoma kunzei	Fungi	Branch dieback in the lower crown with copious amounts of oozing sap. Cankers spread from infection site on branch toward trunk. Needles turn purple or brown then drop. This disease attacks stressed spruce, esp. mature Colorado blue spruce.	Plant on good sites. Avoid wounds and crowding. Maintain plant health. Remove and destroy infected branches in late winter. CHEMICAL: None.
Lirula needle blight, Lirula sp.	Fungi	Inner needles turn a light tan and remain on the tree. Black, slightly raised, elongate fruiting bodies develop on the lower surface of infected needles.	Plant on good sites. Avoid wounds and crowding. CHEMICAL: Make a single application of chlorothalonil by July 1.
Rhizosphaera needle cast, Rhizosphaera kalkhoffii	Fungi	Infection occurs on new needles which discolor and shed the next spring and summer. Needles discolor first yellow then purple or brown. Tiny black fruiting bodies replace the white stomata on individual green or discolored needles and can easily be seen with a hand lens. Trees are predisposed by stress, especially drought.	Avoid stress, especially from drought. Increase air circulation by removing lower branches and mowing grass or weeds. Avoid overhead watering. CHEMICAL: Two spring applications of chlorothalonil will protect new needles from infection.