With petal fall sprays completed throughout the region, the focus for the next few weeks will be on first generation codling moth. The codling moth degree-day model predicts egg hatch from 250 DD to about 1,000 DD. Currently, degree-day accumulations in lower elevation locations (e.g., Cleveland County) are predicted to reach 250 DD this Wednesday (April 30), while in Henderson County 250 is not predicted until May 7.

The number of insecticide applications and choice of materials to apply will depend on: 1) whether or not mating disruption is being used, 2) the intensity of codling moth populations in individual orchards, and 3) weather conditions. The best decisions are made when pheromone traps are being used to monitor the intensity of populations, and use of the codling moth degree-day model to time applications with egg hatch of the first generation.

Mating Disruption: In orchards where mating disruption has been used for 3 or more years, codling moth populations are typically so low that insecticides are usually not needed. However, pheromone trapping is still recommended to confirm the absence of moth activity and/or detect the “unexpected.”  We recommend a threshold of at least 3 cumulative moths captured over a 2-week period to dictate supplemental insecticide sprays under mating disruption (see below for lure types).

Non-Disruption Orchards: Where mating disruption is not being used for codling moth, pheromone trapping is especially important to monitor the intensity of moth populations and help determine frequency of insecticide use during the first generation. While there is not a well established relationship between moth populations and damage, a conservative threshold level of 5 moths over a one week period (using a CM L2 lure) has been successful in minimizing damage.

Pheromone Traps: The type of trap and pheromone lure used is important for codling moth monitoring programs. Either wing traps or Delta traps are recommended. Delta traps are easier to use since they have sticky cards (liners) that easily slide into and out of the trap. Plus the Delta trap provides better protection against rain. Placing traps in the upper one-third of the canopy is recommended, because moth activity is concentrated in this area. Finally, there are several types of pheromone lures available for purchase, but our recommendations have all been developed using the Trece CM L2 lure, which has a 2X rate of pheromone and should be replaced at 8-week intervals. A longer lasting lure (CM L2-P) that needs to be replaced at 12-week intervals has recently been developed and performs similarly to the CM L2.

The number of traps to deploy needs to be a compromise between detection of moths when populations are low and what is practical. One trap per 10 acres of orchard is considered the minimum, but location is probably more important. Traps should be placed at locations where moth numbers are suspected of being high, such as near packing houses, bin storage areas, or adjacent to nearby abandoned orchards.

Codling Moth Degree-Day Model: A codling moth degree-day (DD) model that predicts egg hatch of each generation was developed in the 1970s in Michigan, and has been a key tool used to time insecticide applications. The original model has been refined and updated with phenology data to different regions, including western NC. First generation egg hatch is predicted to occur from about 250 DD through 1,000 DD. However, the length of egg hatch varies considerably depending on the size of the population. Models were developed using high population densities, and only under this scenario does egg laying occur over the entire period from 250 to 1000 DD; hence, the importance of using traps to monitor the intensity of populations.

Insecticide Options: Since 2008, the apple industry has relied primarily on two groups of insecticides for codling moth control – the diamides (Altacor, Exirel, and Verdepryn) and spinosyns (Delegate). While some resistance has been detected in more northern apple areas, to date none has been suspected in the southeast. Relying on only one mode of action (diamides versus spinosyns) during a respective generation has been a good resistance management strategy. It should be noted that under low to moderate codling moth populations, initial egg hatch can occur later than 250, so using an alternative insecticide at 250 DD can help to further minimize use of the diamides and spinosyns. Among the alternatives, Assail and Imidan are the most effective alternatives. An advantage of Assail is that it also has San Jose scale activity.

Relative Efficacy of Insecticides for Codling Moth

Learn more about southeastern apple insect pests at the Apple Insect Management page.

2025 Average Weekly Trap Captures