Tree Identification
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Quercus rubra - Red Oak
Leaf and acorn of Red oak.
New leaves of red oak and catkin like flowers. Look for the small pink-ish pistillate flowers in the leaf axils.
Twig and buds of red oak
Acorns of red oak on a 1 inch grid. Note the shallow caps.
Bark of red oak.
Fall colors - mostly Quercus, predominantly red oak with some bur oak
All Images By: Dave Hanson
  • Characteristics
  • Disease Management
Red Oak: Minnesota native and the state tree of New Jersey, a member of the red oak family which in Minnesota includes red oak (Quercus rubra), northern pin oak (Quercus ellipsoidalis) and black oak (Quercus velutina). This group of oaks rapidly succumbs to oak wilt.
Large tree height: 50-70'
Canopy spreads: 40-50', Rounded crown
Drought Tolerance: Intermediate
Shade Tolerance: Intermediate
Soil pH Tolerance: Intolerant to high pH
Poor Soil Drainage: Intolerant to flooding
Salt Tolerance: Sensitive to salt spray and Tolerant of soil salts.
Alternately branched tree with rough, deeply fissured bark. Foliage is dark green in summer with the fall foliage red to brown. The foliage tends to hang on the tree throughout the winter. Flowers, monoecious, catkins (staminate) are green and pendent while the pistillate are pinkish, small, erect flowers in the leaf axils. The fruit is an acorn with large crops on 2 to 5 year cycles. Look for smooth, reddish twigs.

This species does best on well watered, yet well drained, fine soils in mixes with other hardwoods. As far as timber and landscape value Red oak is one of the more important, if not the most important species in the genus.

Did you know
During the early years of logging red oak and white oak were separated by the color of the wood. Additionally, white oak was considered the superior choice for its wood and fuel-wood qualities. Today, red oak is enjoying the spot light due to its faster growth to merchantable quality.
DISEASE SYMPTOMS MANAGEMENT
Anthracnose, Apiognomonia quercinia Fungi
 Starts as small brown leaf spots in the inner and lower portion of the canopy during spring rains. Spots develop into large brown to tan blotches often along the large veins. Foliage may shrivel or appear deformed. Defoliation may occur. New foliage often develops following severe infections. Fungus also infects twigs causing small cankers and twig dieback. Most prevalent on white and bur oak. Contrast symptoms with those of oak wilt below. Rake and destroy fallen leaves. Keep irrigation water out of the tree canopy. Prune out dead and diseased branches. Keep trees vigorous.

CHEMICAL: Preventative fungicides should be applied beginning at bud break. Thiophanate-methyl (Warning: tank mix or alternate this with sprays of different fungicides), Bordeaux, chlorothalonil or mancozeb.
Armillaria root rot, Armillaria spp. Fungi
 Check declining trees for white felt-like masses of fungus at the base of the trunk between the bark and the wood. Black shoestring-like strands of the fungus, called rhizomorphs, are also present there and in the soil. Honey-colored mushrooms of the fungus may form at the base of the tree in the fall. Keep trees healthy. Deep water if dry; avoid wetting trunk/root area. Surface watering during warm months softens the main roots in the crown area which favors progress of the fungus. Replant with resistant species such as Scots pine, catalpa, mock orange and sumac.

CHEMICAL: None.
Oak heart rot, Laetiporus sulfureus Fungi
 Fungus invades the roots, trunk and butt of tree through wounds causing a brown cubical rot. First evidence may be the production of a fleshy, yellow shelf fungus on the trunk. However, presence of the fungus suggests considerable rot within and possibility of a hazard tree should be investigated. Keep trees healthy and avoid wounds. Prune properly.

CHEMICAL: None.
Oak leaf blister, Taphrina caerulescens Fungi
 New growth develops yellow green flecks which develop into a puckered or raised area on the leaf surface. Area is hollow or empty beneath. The blister may have a reddish cast. Mostly a curiosity in wet years. No control usually needed.

CHEMICAL: Spray once in spring before bud swell with chlorothalonil or mancozeb.
Oak wilt, Ceratocystis fagacearum Fungi
 Wilting and scorching of leaf margins in the upper crown of the tree. May occur first on one limb. Leaves completely brown and remain attached. Oaks in the red oak group may completely wilt and die in two weeks following the first symptoms. Infection in white oaks is slow to progress.

REFERENCE: Oak Wilt, MI-3174(MN).		 DO NOT prune oak trees between April 15 and July 1. If damage occurs during that period, immediately cover exposed areas with a tree wound dressing. Do not transport or store oak from recently wilted trees. Use a vibratory plow to sever root grafts before removing infected trees. Consult a professional arborist.
Smooth patch, Aleurodiscus sp. Fungi
 The outer rough bark of white and bur oak trees sloughs off exposing the lighter-colored smooth inner bark. The fungus does not attack living plant parts. No control is necessary.