Minnesota Tree Care Advisors

Characteristics
Disease Management

Swamp White Oak: a native tree, a member of the white oak family which in Minnesota includes bur oak and white oak as well. This group of oaks can survive oak wilt.

Large tree height:		40-60'

Canopy spreads:		30-60', Rounded crown to broadly columnar in some parts of its range.

Drought Tolerance:		Tolerant

Shade Tolerance:		Intermediate

Soil pH Tolerance:		Intermediate to high pH, prefers and acidic soil.

Poor Soil Drainage:		Tolerant to flooding adapts better than other oaks to heavy wet soils

Salt Tolerance:		Sensitive to salt spray

Alternately branched tree with interesting rough, flaky to shaggy bark. Younger branches may have an curled, papery bark that is light tan to orange in color. Foliage is dark green on the surface and distinctively white on the underside in summer and becomes yellow-brown to brown in the fall. The species name "bicolor" refers to the dark green upper leaf surface in contrast to the whitish underside of the leaf.

Flowers, monoecious, or catkins are green and fruit is an acorn.

This species is available in the nursery trade, sometimes under the name bicolor oak and is being utilized as a street tree.

Did you know
Swamp White Oak is an easy one to spot from a distance when the wind is ruffling the leaves. The underside shines brightly on a sunny day. This tree is lumped in with the other white oaks when handled as a lumber tree. Typically, this species does not occur in large merchantable stands.

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.