Plant Health Problems
Diseases caused by Fungi:
Anthracnose, Gloeosporium fagi.
Leaves of cultivated beeches, especially the copper beech, develop
irregular, light-brown areas which move inward from the margins or appear as
isolated spots within normal green tissues. This condition is favored by cool,
wet spring weather.
Rake and dispose of the fallen leaves to reduce the chance of infection in the
following season. Fertilize trees in the spring and water well during drought
to maintain tree vigor. Since this disease is not a serious problem for the
health of the trees, chemical controls are usually not necessary.
Bark disease, Nectria coccinea var. faginata.
This disease occurs in conjunction with infestation by the woolly beech
scale (see below). Feeding punctures made by the insects kill the living bark
and produce cracks through which the causal fungus enters the tree. The fungus
causes a canker which may be sunken, with small orange lumps of fungal tissue
on the surface. Leaves are usually yellow and small, and the tree lacks vigor.
When cankers are large enough to encircle the twig, branch, or trunk, the
foliage wilts, and the parts of the tree distal to the canker die. Infection
usually does not occur when the insects are removed soon after infestation.
Fertilize trees in the spring and water well during drought to maintain tree
vigor. Control the scale to prevent further infection.
Diseases caused by Physiological/Environmental Factors:
Leaves of beech are very tender when exposed to hot sun after prolonged
cloudy weather, particularly when young. This "burning" may also be
caused by too much fertilizer or by root injury.
Beech blight aphid, Grylloprociphilus imbricator.
This blue aphid punctures the bark. The insect may be covered with a cottony
substance and may also be found on the leaves. Imidacloprid, which is among the
compounds registered for control of this pest in Connecticut, can be applied as
a systemic to be taken up by the roots. Consult the label for dosage rates and
Beech woolly aphid, Phyllaphis fagi.
This aphid infests the under surface of leaves of the European beech and causes
purple circular spots to appear scattered over the leaf. However, the aphid is
not found on the white or American beech. It secretes white wax and infested
leaves appear as though small tufts of cotton were fastened to them. Malathion
or insecticidal soap, which are among the compounds registered for control of
this pest in Connecticut, can be sprayed on the undersides of the leaves.
Imidacloprid may also be applied as a systemic to be taken up by the roots.
Consult the label for dosage rates and safety precautions.
borer or pole borer,
This black-headed borer makes galleries in the wood and holes in the bark. The
adult beetle is brown and about 3/4" long. The life cycle is three or four
years. Adults are present just before flowering. Mechanical injury to the bark
attracts adult beetles and enables them to deposit eggs very easily. Avoiding
injury to bark and providing adequate irrigation during periods of drought can
prevent injury. Trunk sprays of permethrin or carbaryl, which are among the
compounds registered for control of this pest in Connecticut, can be applied to
kill adults before they have a chance to lay their eggs. Consult the label for
dosage rates and safety precautions.
Saddled prominent, Heterocampa guttivitta.
Occasional outbreaks of this insect have been responsible for periodic
widespread defoliation of shade and forest trees in the mountain regions of New
England and New York, especially of beech, birch, and maple trees. The eggs are
laid on the leaves early in July and hatch in 9 days. The caterpillars become
fully grown in about 5 weeks, when they pupate and overwinter in the ground.
There is only one generation each year. The mature larva is about 1 1/2"
long with great variation in color and markings. Some are light yellowish-green
and some are nearly purple. Many have a purple mark or saddle near the center
of the body, but some have no saddle marks and there are all intergradations.
The moth has a wing spread of 1 1/2 - 2 inches and is olive gray in color
without prominent markings. Carbaryl, malathion, spinosad or Bacillus
thuringiensis var. kurstaki, which are among the compounds
registered for control of this pest in Connecticut, can be sprayed on infested
foliage. Consult the label for dosage rates and safety precautions.