 |
English Oak - Quercus robur
Family: Fagaceae - Beeches, Chinkapins and Oaks
Leaf type and persistence: deciduous. Leaf blade length: 4 to 8 inches;
2 to 4 inches. Fall color: copper. Flower color: brown. Flower
characteristics: inconspicuous and not showy. Fruit shape: elongated;
oval. Fruit length: 1 to 3 inches. Acorns attract squirrels and other
mammals. Acorns and twigs cause considerable litter problems. Light
requirement: tree grows best in full sun. Soil tolerances: clay; loam;
sand; alkaline; well-drained. Drought tolerance: high. Aerosol salt
tolerance: high.
|
|
|

|
although not widely used in the United States, English Oak
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. |
|
|
|

English Oak Foliage

An oak "hedgehog" gall on a white oak leaf. This growth is induced
by a small cynipid gall wasp whose larva develops inside. |
|
Several insects attack oak
trees. They are usually not important but may become
epidemic and kill weakened trees. Economically, the most
important are the wood borers. These may damage the wood
of standing trees and cause log and lumber defects.
White oak is attacked by several leaf eaters including
the gypsy moth (Lymantria dispar), orange-striped
oakworm (Anisota senatoria), variable oakleaf
caterpillar (Heterocampa manteo), several oak leaf tiers
and walking stick. The Cynipid wasps cause galls to
develop on the leaves, in the acorn or on the cup.
White oak also hosts various scale
insects, gall-forming insects, and twig
pruners, but most of these are of minor
importance. White oak acorns are commonly
attacked by insects, in some cases affecting
half the total acorn crop. Weevils of the
genera Curculio and Conotrachelus cause most
acorn damage. Light acorn crops usually are
more heavily infested than heavy ones. Two
moths damage acorns, the filbert worm
(Melissopus latiferreanus) and Valentinia
glandulella.
|
|
|
|
|

This English Oak was started from acorn 75 years ago. It is nearly 100
feet tall.
|
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. 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.
(United States Department of Agriculture
NRCS Plant Fact Sheet ST-558)
|
|
|