Horse
chestnut trees are native to southern Europe but were bought to the
United States by the colonists. Today, they grow across the country as
ornamental shade trees or street trees. While the chestnuts (conkers) produced
by this tree are toxic to man and beast, the trees are subject to a number of
horse chestnut pests. Read on for information about horse chestnut bugs and
other pests of horse chestnut trees.
What’s Wrong with My Horse Chestnut?
Horse chestnut trees, also called conker trees, are
imposing. They can rise to 50 feet (15 meters) or more, with an equal spread.
Their wide branches and lovely palmate leaves make them excellent shade trees.
So, what’s wrong with my horse chestnut tree, you ask? When you see your horse chestnut tree failing, you’ll want to try to figure out the problem as soon as possible. Horse chestnut bugs could be attacking your tree or it might be damaged by diseases like chestnut leaf blotch.
Pests of Horse Chestnut
Leaf blotch often appears in combination with horse chestnut
leaf miner, a tiny moth. The moth caterpillars tunnel into the leaves to feed,
usually in spring. Leaves shrivel up and fall early. If you hold the damaged leaf
to the sun, you should be able to see through the area. You might even be able
to see the leaf
miner larvae in the foliage holes. This appears first on lower
branches, then spreads up the tree.
Another of the common horse chestnut bugs is the horse chestnut scale. It is caused by the insect Pulvinaria regalis. The female lays her eggs in spring and the young feed on the leaves. This pest also disfigures the tree, but it does not kill it.
Other common pests include Japanese beetles, which can quickly defoliate the tree, and tussock moth caterpillars, which also feed on the foliage.
Controlling Horse Chestnut Pests
The presence of parasitic
wasps can help reduce leaf miner numbers. Horse chestnut leaf miners
can be controlled through regular fall and winter cleanup of fallen leaves. Infected
leaves should be disposed of; burning is recommended. Systemic insecticides can
be applied early in the growing season but may need to be repeated in summer.
Horse chestnut scale can also be minimized with parasitic wasps but, most often, the use of systemic insecticide or insecticidal soap is applied in spring to midsummer, followed by a second treatment within 14 days.
Japanese
beetles are difficult to control, though their numbers can be slowed
if their larva (grub
worms) are targeted in fall. Most caterpillar
pests can be managed with Bacillus
thuringiensis.
Horse
chestnut trees are native to southern Europe but were bought to the
United States by the colonists. Today, they grow across the country as
ornamental shade trees or street trees. While the chestnuts (conkers) produced
by this tree are toxic to man and beast, the trees are subject to a number of
horse chestnut pests. Read on for information about horse chestnut bugs and
other pests of horse chestnut trees.
What’s Wrong with My Horse Chestnut?
Horse chestnut trees, also called conker trees, are
imposing. They can rise to 50 feet (15 meters) or more, with an equal spread.
Their wide branches and lovely palmate leaves make them excellent shade trees.
So, what’s wrong with my horse chestnut tree, you ask? When you see your horse chestnut tree failing, you’ll want to try to figure out the problem as soon as possible. Horse chestnut bugs could be attacking your tree or it might be damaged by diseases like chestnut leaf blotch.
Pests of Horse Chestnut
Leaf blotch often appears in combination with horse chestnut
leaf miner, a tiny moth. The moth caterpillars tunnel into the leaves to feed,
usually in spring. Leaves shrivel up and fall early. If you hold the damaged leaf
to the sun, you should be able to see through the area. You might even be able
to see the leaf
miner larvae in the foliage holes. This appears first on lower
branches, then spreads up the tree.
Another of the common horse chestnut bugs is the horse chestnut scale. It is caused by the insect Pulvinaria regalis. The female lays her eggs in spring and the young feed on the leaves. This pest also disfigures the tree, but it does not kill it.
Other common pests include Japanese beetles, which can quickly defoliate the tree, and tussock moth caterpillars, which also feed on the foliage.
Controlling Horse Chestnut Pests
The presence of parasitic
wasps can help reduce leaf miner numbers. Horse chestnut leaf miners
can be controlled through regular fall and winter cleanup of fallen leaves. Infected
leaves should be disposed of; burning is recommended. Systemic insecticides can
be applied early in the growing season but may need to be repeated in summer.
Horse chestnut scale can also be minimized with parasitic wasps but, most often, the use of systemic insecticide or insecticidal soap is applied in spring to midsummer, followed by a second treatment within 14 days.
Japanese
beetles are difficult to control, though their numbers can be slowed
if their larva (grub
worms) are targeted in fall. Most caterpillar
pests can be managed with Bacillus
thuringiensis.