Understanding the current situation with chlorpyrifos regulations and its potential use in Michigan tree fruit during the 2024 field season

What the Dec. 28, 2023, court ruling means for Michigan tree fruit growers who would still like to use chlorpyrifos against labeled insect pests on bearing trees.

In February 2022, the U.S. Environmental Protection Agency (EPA) revoked all food tolerances for use of the organophosphate insecticide chlorpyrifos in response to a lawsuit advocating for banning its use. This was despite already identifying 11 uses that could be exempt from this ruling based on risk data they had examined. A second lawsuit against the EPA protesting this result caused this revocation to be vacated on Dec. 28, 2023.

So, what does this mean?

For Michigan tree fruit growers who have relied on formulations of chlorpyrifos (e.g., Lorsban, Govern, Warhawk) as a dormant spray against sap-sucking insects or post-bloom trunk spray against borers, it means that for now, all previous tolerances are back for at least the 2024 field season. In other words, if you still have chlorpyrifos in your spray shed, you can use it according to the label during the 2024 field season in bearing trees. That said, this doesn’t change whatever specific rules your processor, buyer or export market might have in place around use of chlorpyrifos and maximum residue limits.

If you don’t have any chlorpyrifos in your spray shed, you may find it more difficult to obtain because all but a handful of companies have voluntarily given up their product registrations. It is important to note that if a product is no longer registered, it can no longer be distributed/sold, but while tolerances remain in tree fruit crops, formerly registered formulations, like Lorsban, can still be used.

That said, it is expected that as early as fall of 2024, the EPA will complete the process of revoking tolerances of chlorpyrifos for all but those 11 food uses. Among these 11 uses, in Michigan at least, chlorpyrifos tolerances are expected to remain for apples, peaches and tart cherries, but not sweet cherries. So, while it is possible to use chlorpyrifos in these crops for now, it will be important for growers to be thinking about alternatives to its use and possible pest flare-ups, if they haven’t already.

Back in the spring 2023 issue of the Fruit Quarterly, Volume 31, Number 1, I wrote an article titled “Life After Lorsban” in which I described best practices for managing borers and soft-bodied insect pests in orchards without chlorpyrifos.

These include:

  • Scouting or otherwise using appropriate monitoring tools to know what and when pests are active, for more precise use of available interventions.
  • Using pheromone mating disruption in blocks that are a minimum of 5 acres for the pests for which this is an option (e.g., dogwood borer and the greater and lesser peachtree borers).
  • Using a compatible spreader-sticker to maximize longevity of trunk sprays.
  • Calibrating sprayers to maximize coverage of foliar applications.
  • Choosing systemic materials when pest life stages are protected in curled leaves or under waxy scales.

Specific products and their recommendations, which are based on years of efficacy trials run at Michigan State University or by colleagues at other research institutions, are listed in the latest Michigan Fruit Management Guide E-154 from Michigan State University Extension.

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