This blog post was written by one of our Fall 2022 University of Washington Interns, Justice Correa-West. This blog post shares some of the strategies used to mitigate against codling moth infestation. In Seattle, commonly infested fruit varieties include apples and pears.
The first method of management used this year against the codling moth was cardboard banding. Banding the tree trunks with cardboard during the winter months, before May, can encourage the larvae, who conventionally form their cocoons in the bark of the tree, to form them in the cardboard. It is best if the carboard is at least 2-inches wide and is placed 12-18 inches above the base of the trunk. The cardboard needs to be removed by late June and disposed of, as to not allow the codling moth to migrate back onto the fruit after metamorphosizing into adults. Banding can be reapplied by mid-July to address later generations. The larvae will pupate in the bands. This second application of banding will need to be removed and destroyed after the fruit is harvested.
As spring approaches, the time for removing the first round of winter cardboard banding draws near. During the months of April and May the coddling moth emerge from their cocoons. This is why it is so important to remove the bands applied in the winter, before the codling moth metamorphosize. Once the bands are removed, it is time to net! Nets should be applied by late May and should be large enough to cover the entire tree and reach the bottom of the trunk. For more detailed information on how to properly net your tree, take a look at City Fruits guide on How to Net Your Tree.
If netting isn’t your preferred management option, another physical method of IPM management is bagging. Baggies should be placed on the fruit two to three weeks after the blooms fall off the trees and the fruit begin to form into the size of a dime. The baggies themselves can be made up of a wide range of materials such as plastic, paper, or nylon. Nylon baggies, also known as Footies, are not as effective as paper or plastic baggies. In order to allow for natural color and growth of the apples, it is important to remove the baggies 2 weeks before harvesting them. However, be prepared for a lot of work! Individually bagging the fruit on larger fruit trees can be extremely time consuming. It is best to be selective in the fruit you bag on your tree. This means only bagging the “good fruit” that gets the most access to the sun and is developing well, as well as possibly removing any unbagged fruit to minimize the populations of codling moth in your tree.
If you are planning on managing your trees against codling moth, these are some of the next IPM management strategies that you should be preparing to set up in the upcoming months. For more information on codling moth and its different methods of management, go to City Fruit’s fact sheet on codling moth!