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On the Wing: Codling Moth Emerges & PC Delays in the Mid-Hudson Valley Orchards. May 21st, 2021

1st gen. CM larva.

The Brief: The first sustained adult Codling moth (CM) flight occurring on the 11th of May in Highland signals the adult biofix and start of the temperature modeling for the prediction of the larval emergence. Codling moth adults will begin mating and females to begin egg laying over the next few weeks.

Given the cool temperatures we’ve had over the past few weeks and now a significant warming trend, we will have accumulated 111 DD of the 220 DD needed for CM egg hatch today. Given forecast predictions for the next 7 days, and using the 11th of May as our biofix for Highland, NY, we anticipate Codling Moth larva emergence beginning on the 27th of May in orchard sites in the Mid-Hudson Valley locations with historically high CM pressure. (See NEWA Codling Moth Site)

PC & Petal Fall: As of Friday morning (May 21st) we have yet to observe plum curculio (PC) adults and have only seen 1 in 500 fruitlets with PC scars in commercial orchards and unsprayed trees in our research orchard. Very warm temperatures will persist tonight into the weekend, with increasing evening temperatures over the weekend and through the coming week. As we are now well past petal fall in most varieties, we are seeing the early setting apple such as Ginger Gold with king fruitlets exceeding 15mm while all others now sizing in earnest. Generally, cluster king fruit are reaching 8-10 mm in diameter and are now susceptible to PC as temperatures begin to increase.

In choosing insecticides for PC management, considerations should be made based on the mode of action of the active ingredient. John Wise, Michigan Stat Fruit Entomologist, provides a discussion on the Lethal, Antifeedant and Curative Activities of Insecticides that may be helpful in your decision making in tree fruit PC management.

Management for PC should rely on insecticides that hold up under rain events as applications are planned. (See Residual

Plum Curculio adult, scar and egg.

Introduction: Plum Curculio
The model used to calculate the end of PC emergence begins at 95% petal fall of McIntosh. The majority of eggs deposited into fruit by overwintering plum curculio in the Northeast is completed in apples once 308 DD base 50 has been reached. (developed in studies conducted by by W. H. Reissig, J.P. Nyrop, and R. Straub (Environmental Entomology; 1053-1060; 1998; titled “Oviposition Model for Timing Insecticide Applications Against Plum Curculio (Coleoptera:Curculionidae) in New York State”).

In choosing insecticides for PC management, considerations should be made based on the mode of action of the active ingredient. John Wise, Michigan Stat Fruit Entomologist, discusses the Lethal, Antifeedant and Curative activities of insecticides that may be helpful in your decision making in tree fruit PC management. It can be found in the article titles ‘Effectively controlling plum curculio in stone and pome fruits‘. As precipitation can impact the performance of insecticides on fruit crops, insecticides should be considered based on their resistance for wash-off. The article ‘Rainfast characteristics of insecticides on fruit’ discusses the differences between specific active ingredients regarding rainfastness post applications for PC managment.

We recommend maintaining residual protection from the high rate of an effective insecticide for PC. Take note that residual activity is no longer effective when 2 inches of cumulative rain occurs within the first 10 days after application, 1.5 inches of cumulative rain occurring from 10-14 days after application, or 14 days has passed since the previous application with no rain event. Rains Thursday on will significantly impact residual if Wednesday PF applications are made.

PC Petal Fall Options

Introduction: Codling Moth
It can be argued that of the internal worm complex, the codling moth has historically been the greatest threat to tree fruit. This insect continues to re-emerge as a primary pest of apple throughout the world. During the 2016-18 harvest we observed very high levels of fruit infestation in Hudson Valley apple, ranging from 2% to 40% injury in commercial production.

Yearly damage from codling moth (CM) continues to be what appears to be a growing problem in the Hudson Valley. The likely cause may be attributed to a number of factors, one of which is the timely use of very effective insecticides to control the early emergence of 1st generation codling moth larva. Using the 220 DD biofix, management for 1st generation CM larva should begin at the first available application window just before or soon after the earliest emergence date.

Biology: The insect had overwintered as full-grown larvae, residing within a silken cocoons, tucked under inaccessible bark scales, in soil or hidden in the leaves and debris around the base of trees. The larvae pupated prior to bloom and began to emerge in mid-May with very high trap captures in some sites.

In the Hudson Valley to date I don’t believe resistant strains are widespread, even though we are hearing of increasing reports of CM damage to tree fruit. In a study conducted in 2005, it became apparent that WNY CM had a lower level of susceptibility to the OP’s (Imidan) with early signs of decline in efficacy employing Phosmet throughout the Hudson Valley. The broad availability and use of insecticides that include different IRAC classes of active ingredients we now have provide multiple classes to be used to reduce the resistance potential of CM in our orchards.

The range of first flight begins from late April to early May. This season due to a cool spring, with first hatch beginning mid-May continuing through the early part of June. We have been catching moths at the HVRL research orchard since mid-May with numbers per trap exceeding 10 per trap per week at this point.

Adult codling moth

Adult flight is well underway. The use of pheromone traps are the growers best indication of first flight on their farms while providing adult male numbers to understand population density in specific blocks. As they tend to be night fliers, temperatures below 60°F, which we have been experiencing in the Hudson Valley, impede male activity and prevent mating, so a cooler spring will delay significant egg hatch for the first generation. NEWA weather data is available to help predict this, incorporated into the degree day model.

First Generation: The moth has been observed to produce two peaks during the 1st generation, often extending its flight well into the summer. We base our management of the insect on codling moth larval emergence using a predictive degree day model of 220 degree days from CM adult first flight. Two applications, which often start at 1st cover, are needed to cover the emergence period in blocks where CM has caused historical fruit injury. The 2nd application often (but not always) made on the heels of 1st generation obliquebanded leafroller emergence.

Insecticide timing for insecticides classes to manage Codling Moth (John Wise, Michigan State)

Insecticide Options for Management: Numerous options for conventional management are available to reduce fruit infestations. Most conventional insecticides can be applied at 250DD, which include the pyrethroid class, Avaunt, Delegate, Granulosis Virus. Other insecticides targeting eggs need to be applied either prior to egg laying for the material to reside beneath the egg, such as Rimon & Esteem, or over the egg, such as Assail or Intrepid (see chart).

Codling Moth Granulosis Virus Additional options include granulosis virus formulation at 200-250 DD 50°F. High moth pressure requires 2-3 sprays for the first generation, but in lower pressure orchards (with counts of less than 5 moths per trap per week), you can control CM with a single spray timed at 350 DD 50°F.Codling moth granulosis virus. Formulations include Cyd-X, Cyd-X HP, Madex HP by Certis; Carpovirusine by Arysta LifeScience. Cyd-X 0.06SC is applied @ 0.25-0.4 qt/acre and Carpovirusine 0.99SC @ 0.25-0.4 qt/acre.This virus contains an insecticidal baculovirus, Cydia pomonella granulovirus, which is specific to the larval form of the codling moth, and is registered for use in apples, pears, and (Cyd-X only) plums. This biological insecticide must be ingested in order to be effective, after which the viral occlusion bodies dissolve in the larval midgut and release infectious virions. These enter the cells lining the digestive tract, where they replicate; eventually, the other tissues are infected and the larva stops feeding and eventually (within 3-7 days) dies. After death, the larva disintegrates, releasing billions of new occlusion bodies, which may infect other codling moth larvae upon ingestion. No adverse effect to fish, wildlife or beneficial organisms has been observed; it has a low bee-poisoning hazard.

Insecticide Resistance Development in Codling Moth:

The organophosphate class of insecticides, including Guthion (azinphos-methyl) and Imidan (phosmet) have been used since the 1960’s, for over 50 years, to manage the codling moth. The development of resistance by codling moth to Imidan is likely if its reoccurring use has been for Plum Curculio and or OBLR management during mid-summer. Consistent use during the past ten years or more increasing resistance potential. Those specific timings would provide some level of control of CM while providing various rates of residual exposure. Low rates of residual increase the selection for resistance during the early and mid-summer generations of the pest. A scenario, such as the switch from Guthion to Imidan in season long program use woufor plum curculio from PF to 2nd cover and mid-summer management of OBLR, would reduce region-wide resistance of CM to any one specific insecticide class. We have seen the use of these materials to include Avaunt, Exirel, Carbaryl, pre-mixes including pyrethroids or pyrethroids alone. Insecticides of various classes for the overwintering OBLR used at PF would likely impact CM to a lesser degree when used at petal fall timing.

There haven’t been recent studies to detect phosmet resistance to CM in NY that I’m aware of. In Michigan, a study in 2008 detected a 7-8 fold level of resistance in orchard site specific CM populations to codling moth (see abstract from work done by John Wise in Mich. State below). However, no resistance to acetamiprid (Assail) and spinosad (Delegate, Spintor, Entrust) was detected in the study.

That said, it’s very likely we have codling moth populations resistant to older insecticide classes, including pyrethroids and OP’s in orchards throughout the Northeast.

Insecticide rotation: I would suggest the use of specific materials for CM be employed during 1st-2nd cover and again in mid-July, when model predictions for larva emergence are called for AND in orchards with reoccurring fruit injury from CM. The use of Assail to manage apple maggot during 2nd generation CM larval emergence has been a good option, as it’s been shown to be one of the better materials against both CM & AM. The use of Delegate, Altacor at 1st – 2nd cover would reduce the resistance potential while picking up a few lingering overwintering OBLR. Mating disruption and granulosis virus are also good choices in conventional and organic production systems.

Remember to rotate classes for EACH GENERATION and not each spray during a generation, to reduce the potential for insecticide resistance.

Pest Manag Sci. 2008 Sep;64(9):881-90. doi: 10.1002/ps.1576. Resistance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), larvae in Michigan to insecticides with different modes of action and the impact on field residual activity.

Mota-Sanchez D1, Wise JC, Poppen RV, Gut LJ, Hollingworth RM.

The codling moth is one of the principal pests of apple in the world. Resistance monitoring is crucial to the effective management of resistance in codling moth. Three populations of codling moth in neonate larvae were evaluated for resistance to seven insecticides via diet bioassays, and compared with a susceptible population. In addition, apple plots were treated with labeled field rate doses of four insecticides. Treated fruit were exposed to neonate larvae of two populations from commercial orchards.

RESULTS: Two populations of codling moth expressed two- and five fold resistance to azinphos-methyl, seven- and eight fold resistance to phosmet, six- and tenfold resistance to lambda-cyhalothrin, 14- and 16-fold resistance to methoxyfenozide and sixfold resistance to indoxacarb, but no resistance to acetamiprid and spinosad. The impact of the resistance to azinphos-methyl, measured as fruit damage, increased as the insecticide residues aged in the field. In contrast, fruit damage in methoxyfenozide- and lambda-cyhalothrin-treated fruit was observed earlier for resistant codling moth. No differences in efficacy were found for acetamiprid.CONCLUSIONS: Broad-spectrum insecticide resistance was detected for codling moth. Resistance to azinphos-methyl, lambda-cyhalothrin and methoxyfenozide was associated with reduced residual activity in the field. Broad-spectrum resistance presents serious problems for management of the codling moth in Michigan.