PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
INTEGRATED PEST MANAGEMENT (IPM)
MAIN STEPS
Early detection
of invasion is
important
CONTROL METHODS
Legislation
Cultural methods
Sanitation
Biological
Resistant varieties
Plant quarantine
Pest-tested material
Physical/mechanical
Pesticides
Organic, BMP, etc
Combinations
CONTROL
METHODS
1. Plan well in advance to use an IPM program that fits your situation. Keep records
of the crop, eg source of planting material, planting/sowing dates, temperature,
irrigation, fertilizers and pesticides.
2. Crop/region. IPM programs are available for different species of snails and slugs on
a range of crops in particular regions. List the crop problems in your region.
3. Identification can be difficult. Be familiar with local species. Consult a diagnostic
service if necessary (page xiv). Identification is important because certain baits
are more effective against some species than others and rates of bait depend on
the species, eg for conical snails use bait with smaller pellet size. Obtain fact sheets
to understand life cycles, conditions favouring, etc.
4. Monitor populations before planting, sowing, harvesting, spraying or baiting, etc,
as there is a relation between snail and slug numbers and plant damage. Know
when, where, what and how to monitor. Monitor damage to plants. Although it
may seem that the best time to ‘catch the pests in action’ is to look for them at night,
their colour makes them difficult to locate. Detect slugs early in the season using
shelter traps, eg moist hessian bags laid on soil. Slugs invade from the crop edges.
5. Thresholds are important and will depend on your crop, economics and any legal
requirements, eg quarantine. It might be 20/m 2 white snails/m in cereals and 5/m 2 in
canola. Some baits are more effective than others if snail numbers are high.
6. Action. Compliance with quarantine, snail-freedom, organic standards, etc may be
required. Many control methods will be preventative, eg sanitation, rough mulches.
Choose appropriate control measures strategically and early to avoid potential
major pest problems. Move fast if numbers large. Baiting or spraying may work
better in some combinations in commercial crops while hand control may be
sufficient for home gardeners, combined with traps and baits. Toxicity of chemicals
to children and pets must be a consideration. Populations of some snails, eg common
garden snail, need to be excessively large and pasture availability limiting before
control is warranted. Chemical control is more effective when used in combination
with other control methods.
7. Evaluate your current program. Recommend improvements if required. Differences
in success depend on the snail species, the crop and the cropping system.
LEGISLATION, STANDARDS, ETC
Seed Acts may prohibit the presence of snails in seed.
Plant Quarantine prohibits entry of exotic snail and slug species and regulates
compliance with importing countries regulations (page 234).
Pesticide and Safety Acts regulate molluscicides (baits and sprays). Permits may
be required for minor crops, eg herbs.
Threatened Species and Conservation Act 1995 in NSW provides for
conservation and recovery of threatened species.
AS 6000-2009.Organic and Biodynamic Products outlines minimum requirements
be met by growers wishing to label their products ‘organic’ or ‘biodynamic.
CULTURAL METHODS.
Use trickle irrigation instead of sprinklers where possible to reduce moisture and
breeding and sheltering, especially of slugs.
Cultivation kills eggs and adults providing a sterile habitat from which survivors
migrate. A short fallow period can improve this effect. Cultivation in spring can
drive snails from cover crops or weeds into young foliage.
Slashing, grazing and cultivation during summer can reduce snail numbers by
exposing them to increased soil surface temperatures, killing them.
Water early in the day to minimize moist areas.
It can be beneficial to change crop sequences.
Skirt trees to provide fewer access points for snails and minimize risk of snails
climbing trees. Raise plants off the ground.
Coco mulch is an inbuilt snail repellent.
SANITATION.
Good sanitation increases the effectiveness of treatments especially baits.
Remove/control weeds. Eliminate places they can hide during the day and breeding
sites, eg rubbish, pallets, boards and rocks, old plant pots and flats.
Collecting snails by hand is suitable for small areas in home gardens, but not so
easy for slugs. Collect immediately after rain, or irrigation which draws out snails
and slugs for collection at night with a torch. Crush, drown in water, or putt them in
a plastic bag and placing in the freezer for several hours then tipping into garbage or
compost. Stomp on them in situ. Start daily and continue weekly until the population
has decreased. Aestivating snails can be dislodged from fence posts, etc.
Place fruit bins in snail-free areas to prevent snails from climbing onto field bins
and being transported into packing sheds.
Inspect inside and outside of all containers that enter or leave the property.
Snails and slugs 233