GARDEN PESTS
From page 30
active in an area. BYDV is a
worldwide virus attacking of
our most important grasses,
as well as wheat and maize.
The Agricultural Research
Council has established four
suction traps to monitor
aphid flight patterns,
including one in Brits.
Winged aphids migrate in
upper-air currents, especially
those of 12m and higher.
Emphasis in this initiative is to
capture migratory aphids
moving into fields from
different geographical areas.
Migratory aphids originate
from host plants on which the
resident population has
reached crowding proportions. If such plants were
infected with the virus, the
disease is easily transferred to
the new host plant on which
the aphid settles and feeds.
By monitoring these migratory
aphids, the numbers can be
used to warn farmers and
smallholders of such activity
and potential 'virus
pressure' associated
with these aphids.
At a home gardening level you should
check your plants
regularly for aphids,
An ant “harvesting” nectar froom an aphid.
at least twice a
week when plants
You might be able to contain
are growing rapidly, in order
the infestation by spraying the
to catch infestations early, so
aphids off the plants with a
you can knock or hose them
hose. If you don't mind
off or prune them out. Many
getting your hands dirty, small
species of aphids cause the
infestations can be wiped out
greatest damage in late spring
by hand.
when temperatures are warm
The best approach to good
but not hot. For aphids that
vegetable production is to
cause leaves to curl, once
prevent pest and disease
aphid numbers are high and
attack rather than trying to
they have begun to distort
cure it. For this you need to
leaves, it's often difficult to
ensure a healthy soil and
control these pests, because
stable environment for plants
the curled leaves shelter
to grow in. The main way in
aphids from insecticides and
which this is done is to
natural enemies.
promote diversity by companMany aphid species prefer
ion planting.
the underside of leaves, so
Work with nature and copy
turn leaves over when
the natural ways in which
checking for aphids. On trees,
plants grow. Insects and
clip off leaves from several
Continued on page 34
areas of the tree.
32
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