Beauty of Birches by Don Urbanus
Birches are a
common sight in the foothills and valley and though not native to California,
they have adapted quite well. Although not in the same family, birches have the
look and feel of our native Aspens and Cottonwoods with fall color that is
mostly just yellow.
The three most
common and tolerant of our hot foothill summers are the European White Birch
(Betula pendula), the River Birch (Betula nigra) and the Himalayan Birch (Betula
jacquemontii). All of them are medium-sized trees growing to about 40 feet
Of the three, the European White Birch is the most beautiful and widely planted
of the birches with its graceful weeping branches and white trunks that slowly
darken as the tree grows older. Unfortunately it also has the biggest problem
with borers. Small holes on the trunk indicate where the borer exited the tree
as a beetle. Usually vigorous and healthy trees that are not stressed donít
have too much problem with borers but it can happen.
In the past, a
borer attack was an eventual death sentence to a birch. Until a few years ago,
the only way to treat a tree with borers was to spray Lindane on the trunk and
hope the next crop of beetles to lay eggs would get wiped out the following year
as they started the burrowing process. Lindane has since been removed from the
market because of its persistence in the environment and possibly some
carcinogenic reasons too. Itís hard to believe that this neurotoxin was used on
humans to treat head lice.
the last few years, new less toxic but more effective pesticides have come on
the market. Bayer, Greenlight and Monterey all have products that can be
applied once a year to ornamental trees and shrubs, normally spring through
fall, for all year control of insects, aphids and borers. They are applied to
the roots either in granular or liquid form so no spraying is necessary. The
insecticide moves up the tree about 4 feet a day until the entire tree is
protected. These pesticides should not be used on stone fruits like plums,
cherries and peaches since the chemical can get into the fruit.
The Himalayan Birch is more upright than the European White Birch with slightly
larger leaves but has a much whiter trunk that stays white the life of the tree
no matter what the size. If you want pure white bark, the Himalayan Birch is
your tree. It is naturally more borer resistant than the European Birch and
takes the heat quite well.
The River Birch
I was initially
in because it didnít seem to take the summer heat and got leaves with burnt
edges. Heritage, a common variety, didnít fare any better than seedlings. Then
Dura-Heat came along and changed my mind. Slightly more compact than the
species, it can take any heat the summer can throw at it and still have that
fresh green look. All River Birch bark turn a soft tan or cinnamon brown and
are curly and flakey. Although not typically white like other birches, their
bark is very distinctive and attractive. Dura-Heat is the most trouble free and
borer resistant of the birches.
of the European White Birch are occasionally
available. The Cutleaf Weeping Birch is strongly weeping with finely dissected
leaves; however, it grows better in the Bay Area where summer heat is not so
intense. A couple purple-leaved varieties, Purple Rain and Crimson Frost, keep
their burgundy color all year and have the same characteristic weeping habit,
although with trunks that are not quite as white. These trees take a lot longer
for their trunks to thicken up and need staking longer than the typical birch.
birches are planted in groves of three or more to imitate a stand of trees in
nature but they can be planted on their own. There is no rule that they have to
be planted in threes. The only ďruleĒ for groves is that they should be planted
in odd numbers of 3, 5, 7, etc. Odd numbers tend to imitate the chaos of nature
whereas even numbers look more formal and organized. Of course, rules were made
to be broken.
regular water but they donít appreciate sitting in soggy soil. If you have very
poor soil or soil that wonít drain, think about planting your birch on mounds.
The mounds can be as low as 6 inches but it will make a world of difference to