Department of Entomology

Southeastern Apple Production ENTOMOLOGY

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.

1. 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.
2. 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.

1. 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.
2. 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.

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension agent.

Southeastern Apple Production
Mountain Horticultural Crops Research & Extension Center
455 Research Drive
Mills River, NC 28759
Phone: 828.684.3562 ~ Fax: 828.684.8715
Email: jim_walgenbach@ncsu.edu

Web Crafters: Anne S. Napier and Steve Schoof
Email: steve_schoof@ncsu.edu

Posted May 19, 2010