Tree Identification
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Acer saccharinum - Silver Maple
Nearly full expansion on these early spring leaves.
Mature samara and below are the early spring flowers of silver maple
Mature samara and below are the early spring flowers of silver maple
Reddish-gray bark which can become quite dark as the tree matures.
The bark of a mature silver maple
Young silver maple showing fall colors.
Black spot on silver maple leaves is not a problem that needs dealing with.
All Images By: Dave Hanson
  • Characteristics
  • Disease Management
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Silver Maple, one of those native trees that is not a popular choice amongst City Foresters due to its propensity to grow quite large and to shed large limbs during storms. Another trait that keeps silver maple on the "black" list is its aggressive rooting habits. The tree is found throughout most of Minnesota's river bottom land and readily seeds into other areas.

Large tree height: 40-70'
Canopy spreads: 30-50', Oval crown.
Drought Tolerance: intolerant Shade Tolerance
Shade Tolerance Tolerant
Soil pH Tolerance Intolerant to high pH
Poor Soil Drainage Tolerant to flooding
Salt Tolerance Sensitive to salt spray and Intermediate in tolerance to soil salts.

Oppositely branched tree with smooth gray bark when young that matures to a shaggy bark that curls off in vertical strips. Foliage is dark green in summer and becomes yellow to brown with some reds in the fall. Flowers, perfect, are reddish and fruit is a winged samara.

There are varieties to be found in the nurseries, however; this is a tree that should be planted where it has room to grow since it does not age gracefully (can become a liability). Prefers river bottom type soils that are rich and moist, yet this tree tolerates a variety of conditions.
DISEASE SYMPTOMS MANAGEMENT
Anthracnose, Discula species and others Fungi
 Tan/brown/black spots and blotches develop on leaves during wet periods. Spring infections result in leaf distortion. Necrosis may follow the veins. Rake up and destroy or compost fallen leaves. Promote tree vigor. Not seriously damaging to healthy established trees.

CHEMICAL: Preventative fungicides should be applied beginning at bud break when deemed necessary. Bordeaux, chlorothalonil, fixed coppers, mancozeb, thiophanate-methyl or zyban.
Leaf spot, Phyllosticta minima Fungi
 Well-defined lesion on the leaf surface with a light-colored center and dark margin at maturity. Tiny black dots (fruiting bodies of the fungus) are often visible. Rake up and destroy fallen leaves. Avoid wetting the tree foliage during irrigation. Promote tree vigor. Seldom damaging to healthy, established trees.

CHEMICAL: Treat preventatively with Bordeaux 8-8-100, fixed coppers or mancozeb.
Target-shaped canker, Nectria galligena, Eutypella parasitica Fungi
 Perennial cankers develop around wounds on immature trees, usually within 10 feet of the ground. The trunk is swollen around the canker, which often has a ãtarget-likeä appearance. Plant on good sites in proper zone. Prevent damage to trunk and limbs. Promote tree vigor. Remove branches with cankers. May become a hazard tree and should be evaluated as such.

CHEMICAL: None.
Tar spot, Rhytisma acerinum Fungi
 Roughly circular, raised black spots on the leaf surface which resemble spots of tar. Seldom a problem. Maintain tree vigor. Infected leaves can be raked up and destroyed or composted.

CHEMICAL: None necessary.
Wilt, Verticillium dahliae Fungi
 Slow growth, dwarfed foliage and/or wilting. Leaves with scorched margins. Defoliation. Often occurs on only one part of the tree. Green to black vascular discoloration may be present in the sapwood of larger branches and the trunk. REFERENCE: Verticillium Wilt of Trees and Shrubs, AG-FO-1164 (MN), Deciduous Tree Diseases, PP-697 (ND). Fertilize to promote growth; keep nitrogen to a minimum. Prevent moisture stress. Remove dead limbs. Do not plant susceptible tree species where Verticillium is present in the soil.

CHEMICAL: None. NURSERY: Preplant fumigation.