Insecticides
375
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Safety - page 25 • First aid - page 33 • Resistance management - page 41
Chemical Insect Control in Alberta
The degree of infestation and severity of insect
damage varies drastically from area to area and
season to season. Most pests, such as grasshoppers,
cutworms and Bertha armyworms, require control
during periods of abundance that may last from one to
several years. Other pests, like flea beetles, require
control annually in some parts of Alberta.
Chemical control
A number of factors should be considered once the
decision to apply an insecticide has been made.
Insecticides will kill the pest insect if applied properly
at a stage when the pest is susceptible. An application
made too early or too late in the life cycle may not
provide adequate control. Other factors to consider
include: ability of the insecticide to penetrate through
the plant foliage, weather conditions, age and size of
the insect, wait period to grazing or harvest and
dosage required. If insects are moving into crops or
emerging over an extended period, several
applications in the same season may be necessary
since most insecticides have limited residual
properties when applied to foliage.
Safety
In general, insecticides are more toxic to
humans, wildlife, fish, bees and other
non-target organisms than herbicides or
fungicides. Follow label directions for safety
precautions associated with application of each
insecticide. Refer to the introductory section of this
book for general information on safety precautions
associated with pesticide use.
Bee safety
The insecticides used to protect crops from damaging
outbreaks of insect pests can also kill beneficial
insects. The objective of the insecticide application is
to remove the problem insects from the crop with the
least possible impact to beneficial insects such as
honeybees and leafcutter bees. Because bees play a
critical role in pollinating certain crops, it is important
to ensure that an insecticide application has a
minimum impact on population numbers. Although it
may not be possible to totally eliminate the effect of
insecticides on beneficial insects, the impact can be
greatly reduced when the agricultural producer,
pesticide applicator and beekeeper work together.
Beekeepers should:
•
Talk with the landowners near their bee yards
before spray season and provide the producers
with their phone number.
•
Ask producers if spraying to control insects is
likely this year.
•
Ask the producer to provide them with notification
48
hours in advance of applying
an insecticide.
Producers and applicators should:
•
Check for potential insect infestations in field
crops early and frequently, and determine the
economic thresholds for problem insects so that a
spray program can be planned should it be
required.
•
Notify beekeepers of intentions to spray 48 hours
in advance of spraying.
•
Avoid application of insecticides to crops in bloom
or to fields containing blooming weeds, which
are attractive to foraging bees. Where feasible,
use a preventative program early in the season
when insecticides may be as effective and crops
are not blooming.
•
Spray late in the day or early in the morning
when the temperature is below ideal foraging
temperatures to reduce direct exposure to bees.
Honeybees are most active when the temperature
is above 18°C (72°F), usually in the heat of the
day. As a general rule, evening applications are
less hazardous than morning applications.
•
Where there is a risk to bees, use an insecticide
that has short residual activity to reduce the
impact on the bees and to reduce possibilities
of residues occurring in honey and pollen.
•
Learn about pollination requirements of the
different crops grown and about honeybees and
leafcutter bees.
Caution
Unusually low temperatures during and immediately
following applications cause insecticides to remain
toxic to bees for a much longer period than normal.
High temperatures will extend the foraging period,
and application time must be adjusted accordingly.
Prevent insecticides from drifting into adjacent
blooming crops, roadsides and pastures with weeds
in bloom, water used by bees, leafcutter shelters or
apiaries by maintaining a reasonable distance from
field boundaries and allowing for the potential
movement of insecticides by wind. For more