PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
CONTROL
METHODS
(contd)
PHYSICAL AND MECHANICAL METHODS.
These are the most common, best known and often the most effective means of
controlling some vertebrate pests.
Physical methods.
Frightening devices. Where times of protection are short or where methods can
be varied continually, as in a home garden, these devices may keep pests, chiefly
birds, from crops. Frightening devices include:
– Visual scaring devices include:
Scarecrows.
Flying kites of hawks, owls, flattened cats, balloon eyes.
Displays of dead birds, fish or other animals.
Flashing mirrors, such as Eagle Eye, aluminum foil, flags. Strings and bottle tops
over roses and seedlings will provide some protection to seedlings.
– Acoustic devices include:
Widely used in country areas to disperse birds, eg rotating gas guns, which
produce loud explosions at variable intervals. Maximum sound levels have to be
observed.
Humming lines, chimes, holograph tape.
Rustling plastic shopping bags, etc.
– Others include:
Iridescent metallic tape with patterns of eyes of an owl or snake. As light hits the
tape a scary 3D effect occurs, the tape rattles in the breeze.
Electric grids.
Communication signals may be:
– Attractive, eg food-finding, courtship calls. These have so far not been used as a
method of vertebrate pest control.
– Repellent, eg distress or alarm calls, can control vertebrate pests, especially
birds. Animals avoid protected areas. Units can be expensive.
Bird-repelling systems for commercial crops include Bird Gard, eg Bird and
Bat Control, Flower Fruit Scarer, and Crop Gard. Bird-call recognition software
might solve bird problems in orchards.
Electronic Garden Pest Repellers beam ultrasonic sound into a small area
keeping dogs, cats, rabbits, some rodents and possums away.
Habituation seems to be less of a problem with communication signals than
with frightening devices.
– Where habituation does occur, changing the signal usually restores effectiveness.
Since most species have a variety of alarm signals, this is usually easy to do.
– Distress and alarm calls move the pests, but do not destroy them. Usually the
birds find alternative food that is not economically important.
.Mechanical methods.
Fences
Prickly shrubs
Operations.
– Shooting to control their numbers, eg geese, kangaroos, wild dogs. Assisted with
night vision, thermal imaging, helicopters. Not suitable for urban areas.
– Neck dislocation of pest birds caught in traps.
Barriers are a humane method for excluding vertebrate pests.
– Fences control the movement of rabbits, dingoes and kangaroos; The most famous
one being the rabbit proof fence to stop rabbits spreading to WA from the eastern
states. Dingo fences protect sheep flocks from dingoes which also regulate kangaroo
and emu numbers.
– Sealed containers/packets protect seed and other foods from rats and mice.
– Flying pests. Netting, bags and stockings protect fruit from birds and other pests.
Individual bunches of bananas, grapes, may be bagged.
Bird netting. Entire fruit crops may be covered with netting (complying with
ISO 9002 and other Standards) to protect them from birds and hail, enable better use
of chemicals, reduce drift, break rain into fine mist, reduce evapo-transpiration,
wind and sunburn damage, increase temperature and prevent frost damage. 'Vinenet'
(for vines) also protects tropical fruit, eg lychees, from birds and insects, eg
fruit-piercing moths. Bird netting excludes birds from stadiums. A canopy of
foliage can act as a barrier against birds, as they fear ambush. Prune to provide leaf
cover and concealment. netting protects tree trunks.
Bat netting is used for fruit bats and larger birds. Growers in some areas can
apply for low interest loans to erect exclusion netting for fruit bats as part of a
Special Conservation Scheme.
Wires, lines protect roses from birds, netting over seedlings of vegetables.
Roost inhibitors include bird coils and spikes. Electrified ledge landing sites
on buildings (Bird-shock Flexi-Track) prevent birds settling on buildings and can be
incorporated into the design of buildings.
246 Vertebrate pests