A stately and very unique oak that will reach a height and spread of 50 to 60 feet, English oak is hardy in USDA hardiness zone 5 and will tolerate a range of soil pH and moisture conditions, including occasionally wet soil and dry clay. The crown often appears open with large branches dominating the round crown. It is low branching and pyramidal (when young) with a short, grey trunk. The main trunk is normally straight up or slightly bent up through the center of the crown. Branches develop nicely and the tree typically requires little if any pruning to create good form and strong structure. An under-utilized street and shade tree in drier climates.
Figure 1. Mature Quercus robur: English oak Credit: Ed Gilman, UF/IFAS
General Information
Scientific name: Quercus robur
Pronunciation: KWERK-us ROE-ber
Common name(s): English oak
Family: Fagaceae
USDA hardiness zones: 5A through 8B (Fig. 2)
Origin: not native to North America
Invasive potential: little invasive potential
Uses: street without sidewalk; shade; parking lot island > 200 sq ft; tree lawn > 6 ft wide; highway median
Availability: not native to North America
Figure 2. Range
Description
Height: 50 to 60 feet
Spread: 40 to 60 feet
Crown uniformity: symmetrical
Crown shape: oval, round
Crown density: moderate
Growth rate: moderate
Texture: coarse
Foliage
Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: cleft, lobed
Leaf shape: obovate, oblong
Leaf venation: pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches, 4 to 8 inches
Leaf color: green
Fall color: copper
Fall characteristic: showy
Figure 3. Foliage
Flower
Flower color: brown
Flower characteristics: not showy
Fruit
Fruit shape: oval, elongated
Fruit length: 1 to 3 inches
Fruit covering: dry or hard
Fruit color: brown
Fruit characteristics: attracts squirrels/mammals; not showy; fruit/leaves a litter problem
Trunk and Branches
Trunk/bark/branches: branches droop; not showy; typically one trunk; thorns
Although not widely-used in the United States, the tree appears to be very drought-tolerant and could be used more extensively, particularly in climates such as west Texas with low humidity where powdery mildew may not be a big problem. It also grows well in a wide range of soil from acid to alkaline.
There are a number of cultivars for leaf color and crown form. The most popular is 'Fastigiata' which is distinctly upright or columnar, but varies in spread from 10 to 18 feet due to seedling variation. Leaves turn brown in the fall and persist into the winter. The tree is very tolerant of urban conditions and should be grown and used more often. Powdery mildew is often seen on much of the tree. The cultivar 'Attention' has a narrow crown and may be resistant to powdery mildew.
Generally pest free although mites can be seen on some trees. Powdery mildew can be a serious problem on English oak in humid areas.
Pests
No pests are normally serious.
Galls cause homeowners much concern. There are many types and galls can be on the leaves or twigs. Most galls are harmless so chemical controls are not suggested.
Scales of several types can usually be controlled with sprays of horticultural oil.
Aphids cause distorted growth and deposits of honeydew on lower leaves. On large trees, naturally-occurring predatory insects will often bring the aphid population under control.
Boring insects are most likely to attack weakened or stressed trees. Newly planted young trees may also be attacked. Keep trees as healthy as possible with regular fertilization and water during dry weather.
Many caterpillars including gypsy moth feed on oak. Large trees tolerate some feeding injury without harm. Trees repeatedly attacked, or having some other problem, may need spraying. Tent caterpillars form nests in trees then eat the foliage. The nests can be pruned out when small. Where they occur, gypsy moth caterpillars are extremely destructive on oaks. Fall cankerworm has been a problem in some years.
Twig pruner causes twigs to drop off in the summer. The larvae ride the twig to the ground. Rake up and destroy fallen twigs.
Spider mite infested leaves first look dusty then yellowed, particularly on English oak.
Lace bugs suck juices from leaves causing them to look dusty or whitish gray.
Leaf miners cause brown areas in leaves. To identify leaf miner injury tear the leaf in two across the injury. If the injury is due to leaf miner, upper and lower leaf surfaces are separate and black insect excrement will be seen.
Diseases
Powdery mildew coats leaves with white powdery growth and can be a big problem on English oak.
Anthracnose may be a serious problem in wet weather. Infected leaves have dead areas following the midrib or larger veins. These light brown blotches may run together and, in severe cases, cause leaf drop. Trees of low vigor, repeatedly defoliated, may die. Trees defoliated several years in a row may need spraying, to allow the tree to recover.
Canker diseases attack the trunk and branches. Keep trees healthy by regular fertilization. Prune out diseased or dead branches.
Leaf blister symptoms are round raised areas on the upper leaf surfaces causing depressions of the same shape and size on lower leaf surfaces. Infected areas are yellowish-white to yellowish-brown. The disease is most serious in wet seasons in the spring but it does not need to be treated.
A large number of fungi cause leaf spots but are usually not serious. Rake up and dispose of infected leaves.
Shoestring root rot attacks the roots and once inside moves upward, killing the cambium. The leaves on infected trees are small, pale or yellowed and fall early. There is no practical control. Healthy trees may be more resistant than trees of low vigor.
