PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Control methods
LEGISLATION
LEGISLATION,
REGULATIONS
Legislation and various regulations affect many aspects of pest control and examples
are described under each method of control.
CULTURAL METHODS
LEGISLATION
WHAT ARE
CULTURAL
METHODS?
CONDITIONS
FAVOURABLE TO
THE HOST CROP
CONDITIONS
UNFAVOURABLE
TO THE PEST
REPELLENT AND
BAIT PLANTS
Purchase
one of the
many books
available on
companion
plantings
Cultural methods may be compulsory in some states/territories/regions of Australia
for some pests of some plants. For example, a banana plant must not be planted or
cultivated in a Banana Plant Quarantine Area (BPQA) in certain areas of Queensland
without an inspector's approval, unless the plant (a) is to be planted and cultivated in
a residential plantation, or (b) is an approved cultivar for the BPQA.
Cultural methods involve ordinary day-to-day horticultural practices. They are
usually used in conjunction with other methods and are preventative and are an
essential part all plant management programs.
PLANT VIGOUR, ETC
Balanced irrigation/fertilizer regimes.
– Trees attacked by borers show a marked improvement if their vigour is
stimulated by watering, fertilizing and judicious pruning.
– Plants attacked by sucking insects, eg mealybugs and aphids, can tolerate
attacks better if there is adequate soil moisture.
– Avoid excessive plant vigour, eg oriental fruit moth injury to shoots is more
common on lush growth due to excessive fertilization, watering or pruning.
Genetically modified crops may be able to grow faster, mature earlier.
CONDITIONS
Weather, eg gladiolus thrips is favoured by hot dry weather. Efficient irrigation
can significantly reduce the amount of damage.
Cultivation of soil exposes insects, eg scarab grubs, to birds, desiccation or
mechanical damage. Some larvae and pupae can be buried so deeply that they
cannot emerge or be brought to the surface and desiccate. Note that minimum
tillage may result in an increase of some pests.
Crop rotation aims to reduce pest numbers by depriving them of food. Is
more successful in controlling diseases than insect pests.
– Continual cropping of the same crop risks a buildup of pest problems
specific to that crop. Rotation crops should not be related to the following
crop or a potential weed.
– Crop rotation can assist in the control of insect pests if the pest is either
wingless or can only attack a single group of plants. Potato moth only attacks
potato, other Solanaceous plants and weeds. Lucerne seed wasp can be
reduced with lucerne-free rotations.
– Most established soil pests can be reduced by a period of fallow between
cultivation of pasture and sowing the crop.
– Brassica break crops such as canola or mustard when ploughed in release
toxic bio-fumigants and may suppress some soilborne insect pests.
Harvesting and planting dates, eg early maturing stone fruit varieties can
be harvested before the development of damaging fruit fly populations.
Warning services based on modeling programs provide information on
conditions favourable to the pest, eg moisture, temperature, wind, etc.
Climate change. Research is determining how changes in moisture, temperature,
etc will affect the distribution and severity of current and emerging insect pests.
Windbreaks to protect predators.
COMPANION PLANTS
Repellent plants are reputed to repel certain pests, eg garlic aroma can repel
some species of aphids. One must know which species of aphids is repelled and
the situations where it is effective, eg in a vegetable patch or in a rose garden.
Bait or trap plants attract certain pests and once on that plant they can then be
readily destroyed by picking or spraying. Corn earworm moths prefer to feed on
chickpeas rather than cotton. Patches of chickpeas in cotton crops could be
slashed to stop further development.
Beneficial insect attractants. Coriander attracts hoverflies which feed
on aphids and small caterpillars and so reduce pest infestation in cabbages.
40 Insects and allied pests - Integrated pest management