Page 94 - Tài liệu Ebook cây cảnh Bonsai Basics

96 HEALTHY BO SAl

PESTS

Like all plants, bonsai can fall prey to a
number of parasites, which feed off the
sap, at the expense of the tree. These
pests benefit from the regular watering
and health care given to bonsai. The
following are some common pests,
although indoor bonsai can be suscept-
ible to attacks by white fly as well.

Aphids (greenfly)
As most gardeners will know, these pests
arc hard to eliminate. They are small,
green, yellow or brown insects which live
in colonies on the leaves and stems.
Extremely prolific, they quickly multiply
to form clusters that cover the whole
plant. They weaken the tree by sucking
its sap and also encourage fungal and
viral diseases, which move in quickly
Aphid or greenlly when the plant is weakened. These also
attract ants which establish their nests in
the root ball.
Aphids can be quite easily eradicated
by spraying with insecticide. Old bark
should be scraped, as it often harbours
insect eggs.
One of the most persistent of aphids is
the woolly aphid. This has a white fur
coat which protects the aphid from
Gontact with insecticide. Although sys-
temic insecticide should control this
pest, a better method is to paint it with
methylated spirit. If your tree looks as
though it is developing tiny pieces of
cotton wool, then it has woolly aphid.

Caterpillars
There are many different kinds of cater-
pillars, all with a voracious appetite for
foliage, which attack plant leaves, to the
point of total destruction.
Some of them develop in cocoons o n
the undersides of leaves before appear-
Caterpillar
ing in the daylight. They twist themselves
into silky webs, hence their name, tortrix