Codling moth is back with a vengeance in 2014

Recent trap data suggests that codling moth populations will be heavy, and management action will be required.

The catastrophic freeze of 2012 resulted in a near collapse of codling moth populations in most regions of Michigan. Codling moth populations remained suppressed through much of the 2013 growing season. The last two weeks of pheromone-baited trap data suggest that codling moth populations are returning to normal levels, thus “pest pressure” will be heavy and dedicated management actions required.

At the Michigan State University Trevor Nichols Research Center in Fennville, Michigan, we set codling moth biofix for May 25, thus with the current weather forecast we can expect continued emergence of codling moth adults and widespread oviposition, or egglaying, and first egg hatch early next week. To get the most benefit from a codling moth control measure, Michigan State University Extension recommends growers treat a block after moth captures have been recorded and the accumulation of growing degree days (GDD) required for a particular action, as indicated in Table 1, has taken place.

Table 1. Codling Moth GDD Model and insecticide timings for control

GDD base 50 (post-biofix)

Event

Action

Pink bud

Development of overwintering larvae

Set traps

0 GDD = Biofix (~200 GDD after Jan. 1)

1st sustained moth captures

Set GDD = 0

100 GDD

1st generation egglaying (oviposition)

Timing for ovicide materials

250 GDD

Start of 1st generation egg hatch

Timing for larvicide materials

350 GDD

1st generation egglaying & hatch

Delayed timing if pest pressure is low, or for 2nd treatment if an ovicide was applied at 100 GDD

500-650 GDD

Peak of 1st generation egg hatch

Timing for additional larvicide if monitoring of codling moth activity indicates a treatment is needed

1000 GDD

Expected end of 1st generation activity

 

Egg control

Although several insecticides have limited ovicidal activity, only Rimon is considered a strong ovicide material, thus codling moth egglaying is the optimal timing for this material (Table 2). Rimon applied at codling moth biofix plus 100 GDD also provides excellent control of obliquebanded leafroller and suppression of plum curculio (sub-lethal effects on subsequent generation).

Larval control

The vast majority of insecticides used for codling moth control are aimed at killing larvae, and thus are typically applied beginning at 250 GDD post-biofix (Table 2). Pyrethroid insecticides provide moderate control of codling moth and have a broad activity spectrum, but are generally avoided because their use at this stage that can result in outbreaks of phytophagous mites. Apple growers should be aware that resistance to the organophosphate (OP) compounds has been detected in Michigan orchards throughout the state, such that reliance on OP’s for codling moth control is not likely to provide sufficient control. In addition, populations resistant to OP compounds may also be resistant to pyrethroids.

Delegate (spinetoram) is in the Spinosyn class of insecticides and provides excellent control of both first and second generation codling moth. It kills larvae as they hatch and begin feeding, thus should be applied at the larvicidal timings indicated in Table 1. Delegate has very good activity against obliquebanded leafroller, suppression activity on apple maggots, and limited lethal action on plum curculio when ingested (Table 3).

Exirel (cyazypyr), Altacor (rynaxypyr) and Belt (flubendiamide) belong to the Diamide class of insecticides that work on the insect by activating ryanodine receptors, thus depleting internal calcium and preventing muscle contraction. They provide excellent control of both first and second generation codling moth, as well as obliquebanded leafroller. Exirel and Altacor also provide suppression activity on AM, Exirel reportedly better than Altacor (Table 3).

The neonicotinoids Assail and Calypso will provide very good control of codling moth with a residual action of 10-14 days. These compounds are primarily larvicidal, but also have some ovicidal activity when applied over the top of the egg. Field trials have indicated that use of Assail in combination with pyrethroids or carbaryl can result in outbreaks of phytophagous mites. Assail and Calypso are fairly broad-spectrum materials. In contrast to the insect growth regulators and Diamides, the major secondary targets of these neonicotinoids are the sucking insects, specifically aphids (green apple aphids and rosy apple aphids) and leafhoppers (Table 3). The initial application of Assail or Calypso targeting first generation codling moth will also provide control of plum curculio, oriental fruit moth and spotted tentiform leafminer, and they will control apple maggots.

Belay, another neonicotinoid registered for use in pome fruits, is a broad-spectrum material targeting codling moth as well as aphids, leafhoppers, plum curculio, spotted tentiform leafminer, oriental fruit moth and pear psylla. Research trials have indicated that Belay is not as effective as Assail or Calypso for second generation codling moth.

Proclaim is a codling moth control material in the Avermectin class of insecticides. It has provided good control of first generation codling moth in trials at the Trevor Nichols Research Center and in on-farm demonstration trials. Proclaim also has very good activity against obliquebanded leafroller.

There are several new pre-mix insecticides labeled for codling moth control, including Voliam flexi (thiamethoxam + chlorantraniliprole), Tourismo (flubendiamide/buprofezin), and Leverage (imidacloprid + cyfluthrin) that combine two active ingredients as pre-mix formulated compounds. When these are used for codling moth control, care must be taken not to use a product in the following generation that is in the same insecticide class as either of the pre-mix active ingredients.

Table 2. Chemical class, activity and timing of insecticides used for CM control.

Compound trade name

Chemical class

Life-stage activity

Optimal spray timing for codling moth

Mite flaring potential

Guthion, Imidan

Organophosphates

Eggs, larvae, adults

Biofix + 250 GDD

L - M

Asana, Warrior, Danitol, Decis, Baythroid XL

Pyrethroids

Eggs, larvae, adults

Biofix + 250 GDD

H

Rimon

IGR (chitin inhibitor)

Eggs, larvae

Biofix + 100 GDD
Residue under eggs

M*

Delegate

Spinosyn

Larvae

Biofix + 250 GDD

M

Altacor, Belt, Exirel

Diamide

Eggs, larvae

Biofix + 200-250 GDD

L

Assail, Calypso, Belay

Neonicotinoid

Larvae, eggs & adults (limited)

Biofix + 200-250 GDD
Residue over eggs

M*

Proclaim

Avermectin

Larvae

Biofix + 200-250 GDD

L

Granulovirus

Biopesticide

Eggs, larvae

Biofix + 250 GDD
Residue over eggs

L

Voliam flexi

Diamide + Neonic.

Eggs, larvae

Biofix + 200-250 GDD
Residue over eggs

L-M*

Tourismo

Diamide + IGR

Eggs, larvae

Biofix + 200-250 GDD

L

Leverage

Pyrethroid + Neonic.

Eggs, larvae, adults

Biofix + 200-250 GDD

H

* May cause mite flaring in combination with carbaryl or pyrethroids that kill predacious mites.

Codling moth granulosis virus

Growers should not overlook including granulosis virus in their codling moth management program. This is a naturally occurring virus that goes by the scientific name of Cydia pomonella granulovirus (CpGV). Both of the two commercially available products, Cyd-X and Carpovirusine, are effective. Optimal use of the virus is against young larvae before they penetrate the fruit. The best way to target young larvae is to have the virus present on the surface of the eggs when they begin to hatch. Hatching codling moth larvae will ingest the virus as they consume their eggshells.

There are many options for incorporating virus into your codling moth management program. Deciding how much, when and how often to apply product can be quite confusing. Keep in mind the following factors when trying to sort things out:

  • CpGV must be ingested by the codling moth larva and may not kill it immediately.
  • The virus breaks down in the environment, thus a spray may only be effective for a week or so.
  • The virus is highly lethal, a few OB’s are all that are required to cause death.

Our overall experience is that frequent application of a low rate of product is the best approach for using this biopesticide.

Growers can opt to use the virus as part of a multi-tactic codling moth control program. Rotating it with chemical insecticides is a good means of combating resistance. We suggest the following approaches to incorporating codling moth virus into a management program. If you want to restrict your use to a single generation, target the first generation. Some virus-infected larvae will not die immediately, allowing them to cause fruit damage and even complete larval development. Fortunately, stings or deeper entries in small fruits attacked by first generation larvae often fall off the tree or are removed by thinning. Additionally, research conducted in 2003 revealed that less than 4 percent of the individuals that managed to complete larval development survived to pupate and emerge as summer generation adults. Thus, applications against the first generation can greatly reduce the size of the summer generation that will need to be controlled.

Regardless of the generation targeted, it is best to make at least two applications. If you want to rotate a CpGV product with other controls, try applying a chemical insecticide as the first spray at the start of egg hatch (250 GDD) and the virus as the second spray. This is because more eggs will be present and covered by the virus spray at the later timing. The insecticide and virus could then be rotated again, or the virus could be applied weekly at a low rate for the remainder of the egg hatch period.

Table 3. Relative activity spectrum of compounds against spring and early summer apple pests

Insecticide

Primary pests

Secondary pests

CM

OFM

OBLR

PC

AM

STLM

GAA

RAA

LH

SJS

Delegate

***

***

***

*

**

**

 

 

 

*

Rimon

***

***

***

*

 

**

 

 

 

 

Exirel

***

***

***

*

**

**

 

 

*

 

Altacor

***

***

***

 

*

**

 

 

*

 

Belt

***

***

***

 

 

**

 

 

 

 

Proclaim

**

**

***

 

 

***

 

 

 

 

Beleaf

*

*

 

 

 

 

***

***

 

 

Actara

*

*

 

***

***

***

***

***

***

**

Calypso Assail

***

***

 

***

***

***

***

***

***

**

Clutch

**

**

 

***

**

***

***

***

***

 

Guthion Imidan

***

***

 

***

***

*

 

 

 

 

Pyrethroids

**

**

**

**

**

**

*

*

*

**

CM-codling moth, OFM-oriental fruit moth, OBLR-obliquebanded leafroller, PC-Plum curculio, STLM-spotted tentiform leafminer, GAA/RAA-green/rosy apple aphid, WALH-white apple and potato leafhoppers, SJS-San Jose scale, TPB-tarnished plant bug
* some activity, ** better activity, *** best activity relative to other insecticides

Drs. Wise and Gut’s work is funded in part by MSU‘s AgBioResearch.

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