MSU Extension

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

First generation codling moth (CM) adult emergence began in some of the apple growing regions of the state early last week, but the appearance of cold, wet weather, starting last Wednesday (May 10) impeded subsequent moth flight. Temperatures generally dropped below 50°F during evening twilight hours when adult moths are known to be most active, and rain showers were common. These conditions severely limit CM flight, thus it is likely that very little mating and egg laying occurred during this period. As soon as evening temperatures warm up to around 60 degrees F, though, growers should be regularly checking CM traps in their orchards to establish biofix. Biofix, the first date at which moths are captured in traps, provided that moths are trapped on two successive trapping dates, is the point from which one begins accumulating degree days (GDD50) to predict CM biological development for targeting insecticide applications.

Codling moth GDD model

Options for controlling CM once activity is underway include conventional contact poisons, like the organophosphate (OP) compounds, Guthion and Imidan, and a number of pyrethroid insecticides. These materials primarily target newly emerging larvae at CM egg hatch, beginning at 250 GDD post biofix. Apple growers should be aware that resistance to the OP compounds has been detected in Michigan orchards throughout the state, most extensively in the Fruit Ridge and Southwest production areas. The levels of resistance detected were high enough in those orchards that sole reliance on OP’s for CM control is not likely to provide sufficient control.

Several new materials have become available for CM control and growers are encouraged to include these new products in their CM management programs. Integrating them into CM management programs will not only improve CM control in orchards experiencing problems, but also will help delay the development of CM resistance to OP’s in locations not yet experiencing control failures. One of the best CM resistance management strategies is to use pheromone-based mating disruption. Recognizing this, Michigan apple growers have treated over 5000 acres with CM pheromone over the past few weeks. Area-wide or whole-farm CM disruption projects are now on-going in Kent, Ottawa, Van Buren and Grand Traverse counties. The area-wide or whole-farm approach deploys mating disruption over large, contiguous plantings, rather than in small plots surrounded by other orchards. This tactic makes it more difficult for male moths to move to pheromone-free air and locate mates, while minimizing the movement of mated females from orchards not treated with pheromone into the pheromone treated blocks.

Among the newer insecticides for CM control registered over the past few years are the insect growth regulators Esteem, Rimon and Intrepid. Esteem and Rimon act by suppressing development within the egg, as well as larvae that consume it. Hatching of eggs laid by treated adults will also be inhibited. Eggs are particularly susceptible to these products when laid on top of sprayed residue, thus sprays are timed earlier than most other CM control materials. Suggested timing for the first application is biofix plus 100 GDD. At this timing, Rimon will provide good to excellent control of Oriental fruit moth (OFM), obliquebanded leafroller (OBLR) and spotted tentiform leafminer (STLM), while Esteem will be highly active on rosy apple aphid (RAA) and San Jose scale (SJS). This is the second season that Rimon has been available for commercial use. Last year Rimon generally provided CM control at least equivalent to the best standard material used by growers, and where used as an early first generation CM material, also provided excellent OBLR control.

Intrepid provides good control of CM with a residual action of about 10 to 14 days. This product is an insect growth regulator that primarily affects CM larvae, but also has some activity on eggs and has sublethal effects on adults. The best results have been achieved by taking advantage of the sublethal effects and applying the first spray at biofix plus 150-200 GDD. At this timing, Intrepid will also control OBLR larvae that are still present in orchards harboring high numbers of this troublesome pest. The addition of an agricultural adjuvant is recommended to improve initial spray deposition.

The neonicotinoids, Assail, Calypso and Clutch are another group of compounds that have recently become available for CM control. Assail and Calypso will provide very good control of CM with a residual action of 10 to 14 days. Proper timing and coverage is required to achieve control. The best results have generally been achieved when the first application is made just prior to the start of egg hatch (ca. biofix plus 200-250 GDD). Assail is labeled for CM control at the rate of 2.5 to 3.4 ounces per acre, but the high rate has shown better performance, especially for second generation CM. Application rates near the high end of the label rate are also recommended for Calypso, especially where CM densities are high or for prolonged control. 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, the major secondary targets of these neonicotinoids are the sucking insects, specifically aphids and leafhoppers. The initial application of Assail or Calypso targeting first generation CM will also provide control of plum curculio (PC), OFM and STLM.

Clutch, a new neonicotinoid registered for use in pome fruits, is a broad-spectrum material targeting CM as well as aphids, leafhoppers, PC, STLM, OFM and pear psylla. Trials conducted at the TNRC in 2004 showed Clutch to be most effective against first generation CM applied at the egg hatch timing of 250 GDD and at the high rate of 6-oz/ac rate. Even at the high rate, Clutch has not provided adequate control of second generation CM.

Avaunt, an oxidiazine insecticide registered in apples, is labeled for use against CM, leafhoppers, plum curculio, leafrollers and Oriental fruit moth. It has excellent activity on plum curculio and early season applications in non-OP resistance areas should also suppress codling moth.

Proclaim, a new CM control material (Avermectin class) available for the 2006 season, provided good suppression of first generation CM in trials at the Trevor Nichols Research Complex and has also shown very good activity against OBLR.

Warrior, Baythroid XL, Asana, Danitol and Decis are synthetic pyrethroid insecticides that can provide good control of CM. Pyrethroid insecticides, appear to be more effective in the spring for first generation CM, than summer and have a broad activity spectrum. Pyrethroids are highly toxic to mite predators and should be used carefully to avoid outbreaks of phytophagous mites.

Finally, growers should not overlook including granulosis virus in their CM management program. This is a naturally occurring virus that goes by the scientific name of Cydia pomonella granulovirus (CpGV). Two CpGv products were available for use last year, Cyd-X and Virosoft. This year, a third CpGv product, Carpovirusine, will also be available. 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 CM larvae will ingest the virus as they consume their eggshells.

There are many options for incorporating virus into your CM 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: 1) CpGV must be ingested by the CM larva and may not kill it immediately, 2) the virus breaks down in the environment, thus a spray may only be effective for a week or so, and 3) 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 CM control program. Rotating it with chemical insecticides is a good means of combating resistance. We suggest the following approaches to incorporating CM 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.

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

The work of Dr. Gut and Dr. Wise is funded in part by MSU’s AgBioResearch.

This article was published by Michigan State University Extension. For more information, visit http://www.msue.msu.edu. To contact an expert in your area, visit http://expert.msue.msu.edu, or call 888-MSUE4MI (888-678-3464).