The Michigan Blueberry Azinphosmethyl
Transition Strategy

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Response to the Phaseout

This Phaseout presents an immediate and significant challenge for producers, processors, and marketers of highbush blueberries in leading production regions of the United States, because azinphosmethyl is a central component of growers’ ability to control damaging insect pests that bore into blueberry fruit and contaminate harvested berries. This Transition Plan was developed in Michigan but the information presented here will be of relevance to other blueberry-producing states where transition away from this insecticide is mandated under the EPA’s Phaseout plan.

The Phaseout will require rapid development of effective and economical alternatives. In addition to expedited evaluations of potential alternatives, this industry needs a concerted IPM implementation effort to ensure that this change has minimal impact. The Transition Task Force will hold its first meeting in February 2008 to determine the best course of action to adapt to these changes. The charge of this group will be to:

1. Review effectiveness of currently-available insect controls
2. Design tests for the most promising alternative insect controls
3. Educate diverse blueberry industry audiences about the Phaseout and potential alternative IPM programs
4. Create benchmarks to measure progress toward Phaseout and challenges encountered
5. Regular reports to EPA and blueberry industry on progress

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Potential Alternatives

Blueberry is a minor crop that would not receive many registrations of new insecticides without the efforts of the IR-4 Program. Active engagement in the priority-setting process of IR-4 by a team of blueberry extension entomologists and industry representatives has led to registration of some potential alternatives to AZM for use in blueberry. For example Confirm is registered in blueberry, although this has not provided equivalent control to azinphosmethyl in multiple years of efficacy trials conducted in Michigan. A more active member of the same chemical class, Intrepid, is expected to be registered soon. Other insecticides are in the registration pipeline by manufacturers, in IR-4 field residue studies, or undergoing EPA review and are expected to be registered during the azinphosmethyl Phaseout period.

There is currently relatively little adoption of other insecticides for control of fruitworms in Michigan, and this industry is still dependent on Guthion 50WP.
Esteem, Asana, Danitol, Sevin, B.t., SpinTor, Entrust, Delegate and Confirm are currently registered for blueberry but each of these products has their limitations. Some of these have been registered only recently at the end of 2007 and have had no full scale field testing. Esteem has shown variable and medium efficacy against fruitworms, it is expensive, and is not recommended for this use due to the difficulty of timing and the long period of egglaying by fruitworms that would require multiple applications. Asana and Danitol have good activity against fruitworms, but they are the only broad-spectrum alternatives to azinphosmethyl available to growers at this time. Multiple applications of these pyrethroids are not recommended, to maintain natural enemy populations and also to minimize development of resistance and neither of these products can be used during bloom.

However, growers using IGR insecticides during bloom and one or more pyrethroids after bloom have reported good control of fruitworms in the past few years. Sevin is a carbamate with some activity against fruitworms. It has only half the length of activity of azinphosmethyl and would therefore not be a replacement for this insecticide. It is also very hard on beneficial insects. B.t. was the standard in-bloom insecticide used by growers before registration of Confirm. Use of this is very low due to the very short residual control afforded, the sensitivity to temperature, and the susceptibility to wash-off. SpinTor and Entrust (the organic formulation) are active on eggs and larvae of cranberry fruitworm, but have short residual activity. During the period after petal fall, when egglaying by these pests can extend for a few weeks, this property makes this a relatively ineffective option for growers and this is not ranked highly. This is also easily washed off plants, and since most Michigan highbush blueberries receive regular rain events and are irrigated by overhead sprinklers, SpinTor and Entrust are not effective alternatives to azinphosmethyl for fruitworm control.

Confirm has been registered for a few years in this crop and has received some adoption by growers. A recently-completed USDA-RAMP project demonstrated commercial-scale efficacy of Confirm for fruitworm control but the higher price and more complicated timing and application needed for optimal performance have resulted in this being used primarily during bloom when the bee safety of this product tips the balance towards its use. It is more expensive than Guthion, Asana, or Danitol and so has not been used after bloom once there are more options available.   
 
There is an urgent need for cost-effective alternatives to azinphosmethyl, to provide growers with tools to use for fruitworm control in their IPM programs. Some potential alternatives are in development and are expected to be registered during the Phaseout period.

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Pipeline Alternatives

The six insecticides listed below have shown promise for fruitworm control in research trials conducted by John Wise and Rufus Isaacs at the Trevor Nichols Research Complex in the past 5-10 years. Based in part on these findings, applications for registration have been requested by the manufacturers and by IR-4. Assail, Delegate and Intrepid are newly labeled for use in blueberries and Avaunt is expected to be registered in 2008 or 2009. The others are expected later and will have less time for commercial testing prior to the 2012 deadline for the complete Phaseout.

Table 2. Names and characteristics of potential AZM alternatives

* Newly registered compounds

**Registration expected during 2008 or 2009 season

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Efficacy and economics

For any of these insecticides to be a replacement for azinphosmethyl, growers will first need to perceive that they are effective within the reality of their blueberry production system. Efficacy is not enough, however, as the likelihood of transition is diminished if the cost is high. There may be inherent value to transition away from organophosphates and toward selective insecticides with improved environmental profiles as third party auditing and public scrutiny of agriculture increases.

Our challenge is to find the most effective and least expensive alternatives to azinphosmethyl, and to have those alternatives tested under commercial farm conditions, and to educate the end-users (growers, consultants, scouts) on how to optimally integrate these alternatives into their blueberry farm management.

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Non-Insecticidal alternatives

Biological control of fruitworms occurs by parasitic wasps that attack eggs and larvae, and there can be predation of hibernaculae on the ground. However, none of these can be relied upon for control. There are no commercial products for mating disruption of either cranberry fruitworm or cherry fruitworm and none in development. This is due to the small size of the potential market, and the difficulty in manufacturing the pheromones of cranberry fruitworm which are 16 carbon doubly-unsaturated aldehydes, making them intractable to economical large scale synthesis.

Cultural controls such as mulching and/or tillage have the potential to help reduce pest pressure from fruitworms, but there is only anecdotal evidence for this. More research is needed to determine the level of pest suppression possible from these cultural controls. An additional approach is the removal of wild host plants from the land surrounding blueberry fields, although since blueberry is native to the Great Lakes region, this is practical only in certain farms that do not have high populations of non-commericial blueberry. There are no virus products for control of these two fruitworm species, and there are no nematode approaches for control of these fruitworm species.

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The Transition Task Force

A team of private and land-grant university cooperators will evaluate the potential for transition away from azinphosmethyl with the pest management tools available, and this will be updated annually. We propose to build on the already close working relationships between the MSU blueberry research and extension team, the Trevor Nichols Research Complex, and both MBG Marketing and the recently-formed Michigan Blueberry Advisory Committee to follow the following steps toward transition. The Task Force consists of representatives of these organizations.

The first meeting of this group was held at the Trevor Nichols Research Complex in Fennville, Michigan on Monday February 11, 2008. The following items were discussed at this meeting: the current status of the Phaseout timeline; the available alternatives to AZM and their efficacy; and proirities and approaches to gather data on the field efficacy of alternative programs. Follow this link to view the minutes of the first Transition Task Force Meeting.

This group will continue to develop Best Management Transition Practices to test each year in the implementation plots (see below). If you are interested in taking part in these meetings or are willing to serve on this task force, please contact Keith Mason at Michigan State University, Department of Entomology, either by phone at (517) 242-5909 or by email at masonk@msu.edu.

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Transition Plan

Michigan blueberry growers will require a coordinated program of education in the next 4 years to enable transition to registered alternatives while maintaining efficacy, and without reliance on azinphosmethyl. To achieve this, we will deliver a hands-on training program that emphasizes classroom style meetings to deliver the detailed printed information and on-farm training workshops during the period of fruitworm pest activity. The training meetings will be held at MSU’s Trevor Nichols Research Complex and in the three primary blueberry-producing counties in the state (Berrien, Allegan, Ottawa). We will also hold evening dinner-and-discussion meetings at farms in the main production regions where growers, researchers, and extension personnel can discuss the alternative management approaches and reinforce the appropriate deployment of IPM tactics. Information related to this project will be online at this website throughout the Phaseout period. The target audience for our information will include large commercial blueberry growers as well as smaller U-pick farms, crop consultants, blueberry scouts, and extension personnel.

At the annual meeting of the Transition Task Force, and at other times as necessary, a progress report will be prepared for EPA that will describe the current level of production and pest management challenges being experienced by the blueberry industry as significant milestones in the Phaseout are reached. These will focus on the impacts on blueberry growers as the first restrictions come into force during 2008, and as each successive reduction in allowable active ingredient (AI) is reached, and when aerial application of azinphosmethyl is banned. Anonymous surveys of blueberry growers will be conducted at the end of the season when each of these major changes occurs and the results will be made available during the winter to the Transition Team and to the EPA. We consider this feedback to be an essential component of the Phaseout so that the full impacts of the transition on grower perception of pest management capability can be understood by regulators as they are happening.

View the Michigan Blueberry AZM Transition Plan

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