coddling Moth

Coddling Moth

Keeping Your Trees Healthy: How to Deal with Coddling Moth Infestations

Finding a worm in your apple is bad enough, but finding half a worm is even worse! Light Brown Apple Moth (LBAM) and Coddling Moth are common pests that infest apples, pears, quinces, and grapes. These pests can even attack other fruits such as nashi pears, walnuts, and stone fruits. As a consulting arborist with years of experience, I have seen the damage these pests can do to trees and fruit harvests. In this article, we will explore some of the best strategies for dealing with LBAM and Coddling Moth infestations.

Understanding the Life Cycle of LBAM and Coddling Moth

Before discussing how to deal with these pests, it’s important to understand their life cycle. During winter, LBAMs and Coddling Moths are gestating either in the soil below the tree or the nooks and crannies of the bark. Once the weather warms up, the adult moths emerge and lay their eggs on the tree or the young fruit. These eggs hatch, and the larvae chomp their way into the fruit, starting from the skin and working their way to the core. Once they are full, they return to the soil or bark to gestate as the weather heads back into autumn and winter, and the cycle starts again.

Dealing with LBAM and Coddling Moth Infestations

Now that we understand the life cycle of LBAM and Coddling Moth, let’s explore some effective strategies for dealing with these pests.

  1. Suppression Mulching

Suppression mulching involves using a thick layer of organic mulch to prevent the adult moths from emerging from the soil after their gestation. The following steps can be taken to implement suppression mulching:

  • Scrape back existing mulch around the root zone (without damaging the roots).
  • Add a layer of compost.
  • Add layers of cardboard, overlapping around the base of the tree.
  • Add another layer of compost.
  • Finish with a thick layer of straw-based mulch.
  • Repeat this process two or three times throughout the year.

This system has the added benefit of reducing water loss from around your trees and adding valuable organic matter to the soil.

  1. Hessian Traps

Another effective strategy is to wrap hessian around the trunk of the tree as a trap as spring approaches. This attracts the adult Coddling Moths (mainly females). After leaving this on the tree for a couple of weeks, it can be removed and thrown into the bin, and the process repeated.

  1. Organic Strategies

Inspect the fruit every 10 days and remove and destroy any infested fruit. Do not bury or place the fruit in compost heaps – it must be burnt or fed to animals (try ‘cooking’ it in a sealed black plastic bag in the sun). Ideally, have your chooks or other animals free-ranging under the trees to eat any fallen fruit. Remove any pieces of flaking bark, broken branches, and litter from the within the tree to reduce hiding places for cocoons. Remove ladders, old boxes, and tree props from the orchard, first checking them for cocoons.

  1. Natural Enemies

An important natural enemy of the Coddling Moth is the Trichogramma wasp, which parasitizes the moth eggs. As an adult, this micro-wasp feeds on insect eggs, nectar, pollen, and honeydew. It lives several times longer and destroys many more pests when supplied with nectar. Properly managed cover crops are the key to maintaining high levels of predatory insects.

Impact on Grapes

LBAM larvae (caterpillars) will feed on both foliage and fruit of grapevines. While the feeding damage on bunch stems, flowers, and berries can directly reduce crop yield, the most significant impact to commercial growers is the increased risk of infection by Botrytis cinerea and other bunch-rotting fungi. The larvae spin a protective cover of fine webbing on leaves or in immature grape bunches, which can trap debris inside the bunches and increase the potential for bunch rot development later in the season.

To control LBAM infestations in grapevines, consider using pheromone traps or mating disruption. Pheromone traps use synthetic female sex pheromones to lure male moths into the trap, preventing them from mating with female moths. Mating disruption involves saturating the area with synthetic sex pheromones to confuse male moths and prevent them from finding and mating with females.

Preventative Measures for Healthy Trees

Preventing pest infestations in the first place is always the best course of action. Here are some preventative measures that can be taken to keep your trees healthy:

  1. Good Nutrition

Ensuring your trees are well-nourished is crucial for their health. Fertilize your trees regularly and use slow-release fertilizers to prevent excessive growth, which can attract pests.

  1. Proper Pruning

Regular pruning is essential for maintaining the shape and health of your trees. It also removes any dead or diseased wood, which can attract pests.

  1. Regular Inspections

Inspect your trees regularly for signs of infestations or disease. Catching problems early on can prevent them from spreading and causing more damage.

  1. Healthy Soil

Healthy soil is essential for healthy trees. Ensure your soil is well-draining and contains plenty of organic matter.

Interesting Facts about LBAM and Coddling Moth
  • LBAM and Coddling Moth are two of the most destructive pests of fruit trees in Australia.
  • LBAM was accidentally introduced to California in 2007 and has since spread to other states.
  • LBAM larvae are considered a quarantine pest in many countries, including Australia and New Zealand.
  • The Coddling Moth was named after the “codling,” which is an old word for an immature apple.
  • Coddling Moth larvae can survive in hibernation for up to two years.
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