June 4, 2019

Codling Moth Flight Begins......Very Slowly!

Everyone likes to eat apples, including over 70 insects, and a long list of fungi and bacteria.  To produce good tasting, good looking fruit, we have to control those pests.  We have discussed plum curculio in the May 29 post, but of all the flying pests we encounter in the upper Midwest, codling moth (CM) is one of  the insect pests needing to be controlled the most.  Codling moth is responsible for the proverbial worm in the apple, so to speak! Yet, so far this spring, we have only trapped 2 CM (codling moth) in traps thus far.  With the cooler nights, flight has been remarkably low.  So, before CM flights becomes consistent, let's review the development and movement of CM.

Codling moth (CM) is a small moth whose caterpillars bore into the fruits of apple and pear trees during mid- to late-spring and summer.  Codling moth is the cause of what is often referred to as "the proverbial worm in the apple". The caterpillars of this insect can damage a high proportion of the fruits on apple trees in gardens in a small amount of time. 


Codling Moth Larvae
Newly-hatched larvae (caterpillars) chew through the fruit skin and bore their way to the core. The presence in fruit of one or more holes plugged with frass (excrement) is characteristic of attack by codling moth. The larvae enter the fruit through the sides, stem end, or calyx end, and a syrupy substance may exude from the holes as the fruit matures. Shallow entries called "stings" result when larvae penetrate a short distance and then die from insecticide poisoning or natural causes.


The eggs, larvae and pupae of codling moth each have specific physiological time requirements to complete development before they transform to the next stage. Temperature also affects the flight, mating, and egg laying activities of the adults. Although the minimum threshold for emergence of moths is 50 degrees Fahrenheit, male moths do not fly until temperatures exceed 55.4 degrees F and codling moths do not mate until temperatures exceed 60.8 degrees F in the evening beginning at or right after sunset.
   

Pheromone lure with trapped moths.
To determine when flight begins for codling moth, commercial growers make use of pheromone traps.  Once moths have been trapped for  two consecutive days in a row, a biofix is set  that initiates the beginning of growing-degree-day calculations.  We know that at 100 degree days after the biofix date codling moths begin to lay eggs and those eggs begin to hatch at 250 degree days after biofix.  It is this information that aids in the timing of necessary sprays for codling moth so they do not damage fruit.  Growers wishing to time sprays based on egg development and hatch should make an application of an insecticide at 250 DD (base 50 degrees F) after the first sustained capture of males in the sex pheromone traps.  Here is a Detailed Growing Degree Day Model for Codling Moth.   
 
We have not yet established a biofix for CM this spring and may establish one within the next few days  But for the home orchardist who does not have the benefit of a weather station or other means to calculate degree days, a simple tree growth stage time table can be followed.  Codling moths usually start flying at bloom time or just after bloom time at petal fall and approximately at the same time as plum curculio.  Eggs laid by these moths begin to hatch about two weeks after petal fall, depending on the weather. You can apply the first codling moth spray at this time, about two weeks after petal fall, to prevent larvae from entering the fruit. Because most insecticide residues last 7 to 10 days and moths are continuously present throughout the summer, apply a spray every 7 to 10 days to prevent later broods of codling moth larvae from entering apple and pear fruits. If using a natural product like Spinosad, then spray after every rain due to washoff.  Always follow the label directions of any spray you may use.


Several insecticides can be used for codling moth control including acetmaprid and/or spinosad.  Acetamiprid is a soft, conventional control and is available as  Ortho Flower, Fruit & Vegetable Insect Killer.  This is a ready to use product that contains .006% acetamiprid, and is also available in a concentrate containing .5% acetamiprid, a synthetic organic compound of the family of chemicals that acts as neonicotinoid insecticides. Acetamiprid is a contact, translaminar insecticide for sucking-type insects and can be applied as a foliar spray. Translaminar insecticides are absorbed by leaves and can move through the leaf to the opposite surface they contact. They are not truly systemic and do not move throughout the entire plant. Acetamiprid acts on a broad spectrum of insects, including aphids, thrips, plum curculio, apple maggot and Lepidoptera, especially codling moth.  When sprayed in the evening at sunset, it will not harm bees or other beneficial insects. Be sure to follow all label directions on the bottle for proper application.


An all natural approach is available in the form of Bonide’s Captain Jack’s Dead Bug Brew.  Captain Jack's Deadbug Brew® contains Spinosad (spin-OH-sid), a product first isolated from a naturally occurring soil dwelling bacterium that was collected on a Caribbean island from an abandoned rum distillery. Deadbug Brew® kills bagworms, borers, beetles, caterpillars, codling moth, gypsy moth, loopers, leaf miners, spider mites, tent caterpillars, thrips and more! Use on fruits, vegetables, berries, citrus, grapes, nuts and ornamentals and approved for organic gardening.


For additional information, see the following fact sheets which are available from local university extension services:

http://extension.psu.edu/plants/tree-fruit/insects-mites/factsheets/codling-moth


 Reference in this publication to any specific commercial product, process, or service, or the use
of any trade, firm, or corporation name is for general informational purposes only and does not
constitute an endorsement or certification of any kind by Royal Oak Farm.

People using spray products assume responsibility for their use
in accordance with current label directions of the manufacturer.

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