First Generation
Codling Moth Management
James F. Walgenbach
Extension Entomologist
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Mid-May through mid-June is a critical time for
assessing first generation codling moth populations
to determine their potential for causing damage,
and to make decisions on the need for and timing
of insecticide applications to prevent damage. The
choice of insecticides to use against codling moth
should be limited to only a few chemicals, while
the number and timing of applications will depend
on the intensity of moth pressure in specific orchards.
The only reliable method of measuring the intensity
on a preventive basis is by using pheromone traps
to monitor moth activity, although history of damage
in an orchard is also useful in assessing population
density.
Insecticide Selection
A widely accepted insecticide resistance management
(IRM) practice for the codling moth is to NOT expose
successive generations against the same insecticide
or insecticide(s) with the same modes of action.
The most effective insecticides available for codling
moth control belong to two chemical groups, 1) the
spinosyns that include spinetoram, the active ingredient
in Delegate, and 2) the anthranillic diamides that
include chlorantraniliprole (active ingredient in
Altacor) and flubendiamide (active ingredient in
Belt). Chlorantraniliprole is also sold as a premix
with thiamethoxam (Voliam Flexi). As shown in Fig.
1, first generation codling moth flight occurs in
May and June, and second generation in late July
and August. Hence, if Delegate is
used against the first generation, it should not
be used later in the season when second generation
flight occurs. Instead Altacor (or Belt or
Voliam Flexi) should be used against the second generation.
Alternatively, if Altacor or Belt is used against
the first generation, Delegate should be used against
the second generation.
 Large
plot field trials in North Carolina during the past
two years have demonstrated that the same excellent
level of codling moth control can be expected regardless
of whether Delegate or Altacor is used during the
first or second generations. The most important thing
to remember is that whatever insecticide is used
in May and June against the first generation, it
should NOT be used in July or August against the
second generation. The most compelling argument for
using one product early or late is that Altacor has
longer residual activity than Delegate, and therefore
is a good choice late in the season when both second
generation codling moth and tufted apple bud moth
are potential threats for several weeks after harvest
has begun.
Pheromone Trapping to Monitor Codling Moth
Activity
Pheromone traps to monitor codling moths
are useful tools to help determine the timing and
frequency of insecticide applications necessary to
reduce the potential for damage. Pheromone traps
for codling moth consist of bottom liners (coated
with a sticky substance) covered by a top, and a
lure containing the sex pheromone of the codling
moth is placed inside the trap. Both Delta and Wing
style traps will work for codling moth, but in our
experience Delta style traps are easier to maintain,
capture more moths, and can be reused for several
years. Pheromone lures do not last the entire season
and must be replaced at regular intervals. Several
companies make different types of lures, some that
will last for several months and others that will
last for only a month. During our recent RAMP project
we used Trece L2 lures that emit pheromone for 12
weeks, so they need to be replaced only once during
the season. Finally, because the upper apple canopy
is where codling moths fly and mate, it is recommended
that traps be placed in the upper one-third of the
canopy, which can be accomplished with a bamboo pole
(see the figure below).
 It is also important to recognize that codling moth
populations are not evenly dispersed throughout an
orchard, and there are “hot” spots that
may or may not be predictable. Also, a pheromone trap
will only attract and capture moths that are in close
proximity to a trap (possibly as close as 100 ft),
so it is necessary to have multiple traps in an orchard.
The number of traps required to accurately assess a
population within an orchard needs to be a compromise
between what is actually needed and what is practical.
While the exact number is debatable, it is generally
agreed among tree fruit entomologists that traps should
be deployed at a density of 1 trap for every 3 to 5
acres. But, too few traps are better than no traps
at all! Traps should be checked once per week
and the number of moths captured in each trap recorded
and a permanent record maintained.
When and How Frequently to Spray Insecticides
Decisions
on the timing and frequency of insecticide sprays
targeting codling moth should be based on the intensity
of a codling moth population, because an orchard
with a high population will obviously require more
frequent insecticide use than one with a low population.
Advantages to reducing the number of sprays to the
minimum needed include a cost savings and reduced
potential for codling moth to develop resistance
to new insecticides.
Classifying the size of a codling moth population
is somewhat subjective, but knowledge of the history
of damage in an orchard and the number of moths captured
in pheromone traps are the best tools to determine
the need for insecticide use. Below are some guidelines
on determining the need for insecticide use in orchards
managed with and without mating disruption.
Mating Disruption Orchards
In mating
disruption orchards it should be recognized that
this passive management tool will control low populations
of codling moths, so there are greater opportunities
to eliminate insecticide use compared to non-disrupted
orchards.
- Moderate to High
Populations: In
orchards with damage exceeding 2% the previous
growing season and/or where this is the first year
of mating disruption, one should assume a high
population and make two applications of an insecticide,
with the first at 250 DD and the second 14 days
later. Additional applications should be made when
cumulative average trap captures exceed 3 moths
per trap. To calculate cumulative average, each
week determine the average number of moths captured
per trap in an orchard (i.e. total moths divided
by number of traps), and add the weekly average
to the previous weeks average. When the running
total reaches 3 moths, a supplemental insecticide
application should be made.
- Low Populations: In orchards where
there was no or minimal damage the previous growing
season, and where mating disruption has been used
for multiple years, it is likely that codling moth
populations have been reduced to such low levels
that no insecticide use is necessary. However,
it is critical that pheromone trapping be conducted
to 1) confirm that moth populations are low, and
2) detect outside sources of moths entering an
orchard. Under these conditions, a threshold of
3 cumulative moths per trap (as described above)
can be used as a threshold to dictate the need
for insecticides. NOTE: This
value of 3 cumulative moths per trap is based on studies
that used Delta style traps baited with L2 pheromone
lures and hung in the upper third of the canopy.
Non-Mating Disruption Orchards
In orchards where mating disruption is not
used, there is a higher level of risk associated
with eliminating insecticide used compared to disrupted
orchards, because there is no “backup” control
program to account for potential errors in the interpretation
of trap captures.
- Moderate to High
Populations: Damage
to fruit in the previous growing season exceeded
2% or pheromone trap captures exceeded 10 to 15
moths by 200 DD after biofix. One should assume
a high population and make a minimum of two insecticide
applications, the first at 250 DD after biofix
and the second 14 days later. Additional applications
at 14-d intervals should be based on pheromone
trap captures, with additional applications warranted
if 5 to 7 moths per trap are captured. A higher
trap threshold is used in non-disrupted vs disrupted
orchards, because moths are more easily captured
in non-disrupted orchards due to the absence of
synthetic pheromone dispensers competing for the
attraction of male moths.
- Low Populations: No or minimal damage
to fruit in previous growing season, and pheromone
trap captures do not exceeded a cumulative total
of 5 to 7 moths per trap by 250 DD after biofix.
Under these conditions it is likely that only one
insecticide application is required against the
first generation, and it should be made between
350 and 400 DD after biofix. As above, if at some
time trap captures exceed 5 to 7 moths per trap,
an insecticide should be applied. In the event
that no moths are captured in pheromone traps,
a single insecticide application should be applied
between 400-600 DD after biofix as a safeguard.
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