western-queensland-gardening-guide.pdf - South West NRM

Chapter 8:
ich pesticide to use
(Adapted with permission from the Queenslnnd Agricultural lournal, July-August 1988)
Using pesticides alone to protect plants against pests is not the most effective strategy.
Management of pests, rather than eradication, is more efficient. Removing dead and
rotting plant material and keeping the garden free of weeds that may harbour pests
helps prevent them multiplying. It may even be possible to remove some insects from
the plants by hand or with a hose. en pests are visible in damaging numbers and a
pesticide application is needed, choose the pesticide carefully.
With so many garden pesticides available, the home gardener can sometimes be
uncertain which best suits the pest. A given pest can often be controlled by a variety
of chemicals. Some pesticides are selective, being effective against only a few pests.
Choosing such chemicals may lead to a cupboard full of products, each used
occasionally and eventually deteriorating with lengthy storage.
A better plan is to choose chemicals that have a broad range of activity against a
number of pests, such as Rogor, diazinon, carbaryl, or pyrethrin. In this way,
pesticides in store are fewer and the gardener gets best value for money.
lation of pesticides must also be considered when choosing. Dusts or sprays
can be used to control pests. Dusts do not need ing and are easy to apply.
However, it is some s difficult to get good cover of some plants with a dust,
and it is easily washed off by rain or overhead watering. Spraying gives a better and
more even coverage of the plant, and therefore more efficient control. Recently, readyto-use
spray fo lations which require no ing or dilution have become available
in aerosol and atomiser packs and may be useful in certain situations.
Biological pesticides are also available to the home gardener and may be an alternative
choice in some situations. Such pesticides enable the gardener to conduct germ
warfare against certain pests by spraying them with disease organisms specific to these
pests. For example, Dipelm (a bacterium) may be used to control leaf-eating
caterpillars.
The choice chemical pesticides includes carbaryl, dimethoate, sulphur, pyrethrins,
dicofol, white oil, fenthion, trichlorfon and fenamiphos. Metaldehyde and methiocarb
are used specifically for slugs and snails. All these chemicals appear on the labels of
popular pesticides, and all are of comparatively low human toxicity if used correctly.
Carbaryl, a broad-spectrum insecticide with a short residual life, can be used close to
hamest. It is effective against some caterpillars and leaf-eating beetles and ladybirds,
but does not control caterpillars attacking plants of the cabbage family. Dimethoate is
also a broad spectrum insecticide and miticide. It is effective against fruit fly, aphids,
thrips, jassids and mites. Fenthion also controls fruit fly. Though lacking as wide a
range of activity as dimethoate, it does not injure Meyer lemons and cumquats as does
dimethoate.