Second Generation Codling Moth Beginning to Emerge

As I have mentioned in previous posts, of all the flying pests we encounter in the upper Midwest, codling moth is one of  the insect pests needing to be controlled the most.  Even though codling moth flight began back on June 7 (our biofix date), that first generation of eggs that made it through the first spray protocols have hatched, gone through their 5 instar phases and are now beginning to fly as adult moths.   The first sustained flight of the second generation usually begins at 1200 to 1250 and today we are at 1012DD since that first biofix of June 7, 2019.

Armed with a biofix of June 7, and by calculating the degree days from that biofix date, we can now begin our countdown for our first spray against the "proverbial worm in the apple" for second generation........if we have a second generation that is above our threshold and need to do a spray at all!  If you only have a few trees, your threshold for damage might be much lower than ours here at the orchard with over 17,000 trees.  If you can withstand only a few damaged apples, then you may not need to spray at all.  But if your damage is significant, then your choice may be a needed spray. 

Codling Moth Model

 

To review, degree-days (DD) are determined by use of the average temperature for a day (maximum temperature + minimum temperature/2) and subtracting it from the base temperature  at which the insect does not develop. For the codling moth a base temperature of 50°F is used. (Temperatures above 88°F are upper thresholds for codling moth  activity  and  should  not  be  included in  degree  day accounting.)  As an  example, a day when the high temperature was 80°F and the low temperature was 60°F,  then 20 degree days would accumulate [(80 + 60/2)- 50]. 

 

Here is a Detailed Growing Degree Day Model for Codling Moth.  Following the model, we know that at 1000 degree days after the biofix date the first generation of codling mot end their flight.  At about 1250 DD after that first biofix, the second generation eggs may begin to hatch.  Codling moths begin to lay those eggs around 105oDD and those eggs begin to hatch at about 1250 degree days after that first biofix.  It is this information that aids in the timing of necessary sprays for 2nd generation 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 1250 DD (base 50 degrees F) after the first sustained capture of males in the sex pheromone traps.  If you have no way of monitoring these temperatures for degree days, I anticipate, given the projected forecast for the next week, that a spray date should be around August 3 to August 5. 

CONTROL

There  are only a very limited  number of spray products on the home garden/ consumer market that are available for managing codling moth in home orchards, as I have mentioned in previous posts. All of these require repeated application, timed for periods when eggs are being laid and are hatching, and thorough coverage of fruit.  Let's review these again.

  

Spinosad. Spinosad is a naturally derived material, produced by soil microbes (active ingredient, spinosyns). Several formulations are available, most of which are allowed to be used in Certified Organic production. Combination with horticultural oil is often useful in increasing control and fruit coverage. Applications should be made at 10-14 day intervals during periods when eggs are hatching. Effects of spinosad on natural enemies of fruit-infesting insects generally are minimal, although some are susceptible.

Acetamiprid.  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, 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, but are not truly systemic and do not move throughout the 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.

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

https://ecommons.cornell.edu/bitstream/handle/1813/43086/codling-moth-FS-NYSIPM.pdf

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

 

This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these  recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned.  The author assumes no liability resulting from the use of these recommendations.