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Types of pest control:
Biological controls:
Biological control means introducing a natural predator to
kill off the pest. It is mainly used in greenhouse, as the predator usually
needs temperatures fairly high.
Biological control tends to be expensive but it is extremely
effective as long as the instructions are followed carefully. Natural
predators are now available for amonst all pests.
Especially effective against: Greenhouse pests.
Insecticidal Soaps
Sold as organic pesticides, insecticidal soaps used to be
known as "soft soaps" They contain fatty acids which break down the
insect's protective coating and cause them to die by dehydration. As many
beneficeal insects have hard shells (e.g. Ladybirds) they are unaffected by the
soft soap. Although ladybird larvae and a few other beneficial insects are soft
bodied so insecticide soaps should always be used with the same care as any
other chemical.
Especially effective against: Aphid and caterpillars
Useless against: Scale
incests
Systemic insecticide
A systemic insecticide will get right into the plant systems
and poison anything that attempts to take a bite out of it, the effect usually
last for several weeks. Most systemic insecticides also kill insest on contact.
Special systemic insecticides are sold for vine wevil control.
Especially effective against: Most pests.
Useless against: Red spider
mite.
Most common pests:
Cabbage white caterpillars
A problem of brassicas (cabbages, broccoli, etc..) A hoard
of cabbage white caterpillars can destroy a cabbage path within 24 hours.
Prevention is better than cure; netting around the brassicas will prevent the
butterflies from laying eggs. If you've already got the caterpillars, act
immediately by either picking them off, or by spraying with a general-purpose
pesticide. Alternatively, try this advice from a very old gardening magazine:
Eggshells in large pieces around your brassica-family
vegetables (cabbage, cauliflowers, buk choy etc) deters cabbage
butterflies...they will not lay their eggs, as they think another cabbage
butterfly is there already. However, if it is too late, and you have
caterpillars on your cabbages already...pick off all you can, and put 'em in a
blender with some water, and spray 'em back onto the cabbages. You will not get
any more eggs laid there. Of course..remember to wash your cabbages well before
use!
Red spider mite
Mainly a greenhouse pest as it likes hot, dry conditions. A
red spider mite infestation first shows itself as a yellow mottling on the
surface leaves, a close look at the underside of the leaves will reveal the
tiny brown mites going about their business of destroying your plants. Serious
infestations will have fine webbing all over the plant. You could try
pesticides but the red spider mite will soon build up a resistance to whatever
chemical you use. A predatory mite called Phytoseiulus persimilis will
control it but it will need consistence temperature of 21 dergrees Celsius or
above.
Vine weevil
Mainly a pest of pot grown plants, vine weevil adults will
only nibble at leaves, it is the larvae that does the real damage, eating the
roots of plants. The larvae are active in the spring and autumn. Because they live under the soil, the first sign of vine weevil
attack is often a dead plant, with it's roots eaten off just below the surface.
Since by the time you notice an attack it will most likely
be too late to save the plant, the only option is to either occasional pull the
plant out of the pot and check for the bright white vine weevil grubs, or to
use a preventative systemic vine weevil killer in the autumn on plants which
are permanently pot grown.
Aphids (green and black)
The worst aphids attacks occur in early summer when the
plants have young, tender shoots and before the number of predators build up.
It is usually only young plants that are seriously threatened by aphid. On
large shrubs and trees aphid should be left as they are relied upon by small
birds to feed their young. For aphid control use an insecticidal soaps spray
which will destroy the insects protective waxy coating.
Scale insect
An armoured plated insect that attacks shrubs and young
trees, scale insect is one of the hardest pests to get rid of. Scrap of as many
of the insects as possible, and unless you are religiously organic, give the
plant as dose of systemic pesticide. Keep a close eye on the plant and scrape
of any more scale insects as soon as you see them
Slugs and Snails
Try to encourage natural predators, a health population of
frog, hedgehogs, black birds and thrush will work wonders in keeping the slug
and snail population down.
Any slug-snail subsceptical plant should be well protected;
copper strips can be used to stop the molluscs finding their way to the plants
(the copper give them an electric shock).
Beer traps or "slug pubs" as they're sometimes
known are great for getting rid of slugs. Cheap beers seem to be far more
effective than fine ales, which is just as well.
The occasional slug and snail hunt on a damp evening, with a
bucket of salt water for killing them in is also very effective.
A traditional remedy to the slug problem is to sprinkle
grit, eggshells, sharp sand etc…. around the plants, this does deter them
but if there is a heavy rain over night the protection will wash away, and the
plant will be eaten before you can renew it.
(I have noticed that slug and
snail aren't active so much on spring evenings when it is going to be near or
below freezing point later that night, and I have occasionally used them as
weather-molluscs when I have needed a second opinion on whether it is going to
freeze that night or not.)
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