EPA Considers Delisting Mancozeb for Use in Grape

By Dr. Katie Gold, Cornell Grape Pathology

The US Environmental Protection Agency (EPA) has proposed to cancel the use of mancozeb, a multi-site fungicide commonly used to control Phomopsis, downy mildew and black rot, in grape due to potential post-application worker exposure hazards. The public comment period on this proposed interim registration review decision (PID) closes on September 16, 2024. If this change concerns you, you’re encouraged to submit comments to the EPA here: https://www.regulations.gov/document/EPA-HQ-OPP-2015-0291-0087. (See more about comments below.)

Cornell Grape Pathology is conducting a survey to better understand grape grower habits around the activities EPA cites as risk factors in its decision. Survey responses are due September 6, 2024. All US grape growers are encouraged to weigh in: https://cornell.ca1.qualtrics.com/jfe/form/SV_erKGUlRU2XkorCC.

Why is the EPA re-registering mancozeb?
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) is the Federal statute that governs the registration, distribution, sale and use of pesticides in the United States. Recently the EPA announced its intention to come into compliance with the endangered species act, which has led to a FIFRA re-registration review of many multi-site fungicides, including ziram, thiram, febram, captan and now mancozeb.

Why grape but not other fruit crops?
The EPA is proposing to cancel mancozeb in grape because of potential post-application worker health hazards. There are specific activities in grapevine production that yield post-application hazards above the EPA’s acceptable threshold after a single mancozeb application (at maximum single application rate of 3.2 lb AI/acre). They include tying/training, hand-harvesting and leaf-pulling up to 45 days, and girdling and turning-up for 72 days. The EPA has decided that imposing a restricted-entry interval (REI) of such length would preclude the use of mancozeb because it would impede growers’ ability to conduct other production activities. A lower single application rate (e.g., 2.5lb AI/acre) would still result in risks that could not be addressed with a feasible REI. Other orchard crops do not conduct these activities and are thus able to accommodate the mitigation practices (4-day REI and ban on hand-thinning) the EPA deems necessary to sufficiently reduce post-application worker health hazards from mancozeb.

How did the EPA come to this decision?
The EPA is by mandate required to do a cost-benefit “BEAD” analysis. The Biological and Economic Analysis Division (BEAD) methodology for mancozeb involves assessing the benefits of its use at the acre level and reflecting how growers make pest control decisions. This analysis includes reviewing mancozeb usage data, identifying use patterns, target pests and the attributes that make it valuable for pest control. BEAD also evaluates the biological and economic impacts of using alternative pest control strategies if mancozeb were unavailable, considering factors like cost, resistance management, and crop yield or quality. The methodology relies on data from university extension services, USDA, grower surveys, public comments and professional knowledge, with pesticide usage data provided by sources like Kynetec USA Inc.

Does the EPA understand the impacts of banning mancozeb in grape?
In its BEAD analysis (supporting document EPA-HQ-OPP-2015-0291-0094), the EPA cites the following anticipated impacts:

“With the loss of mancozeb in grape production, BEAD anticipates that at a minimum, grape growers east of the Rocky Mountains will experience an increased cost of pest control as growers will need to integrate more single-site fungicides. The growers would have to rely primarily on captan to control Phomopsis disease and downy mildew and single-site fungicides (e.g., myclobutanil) for effective control of black rot increasing the risk of resistance. Further, single-site fungicides are generally more expensive than mancozeb (Kynetec, 2021a), resulting in additional costs of fungicide treatment.”

What happens now?
The EPA is accepting public comment on its proposed interim decision until September 16, 2024. If you wish to contribute a comment to the EPA, you can type it in online or upload a formatted letter* here: https://www.regulations.gov/document/EPA-HQ-OPP-2015-0291-0087. And/or use the following guidance: EPA is interested in receiving new and relevant information that will inform its BEAD analysis regarding the risk assessment and risk management of mancozeb in the overall grape disease and fungicide resistance management picture. Julius Farado, USDA’s plant pathologist in residence, has shared the below list of information that the EPA will consider relevant if supported with economic, quantitative, scientific data and recent information (not anecdotal).

Adoption of new sprayer technologies that reduce drift and chemical loading to environment (e.g., X number of growers associated with us have adopted Y technology that reduces drift)
Adoption of decision support systems (e.g., forecasting tool) adopted by growers that reduce fungicide applications (e.g., We invested in weather systems to improve NEWA model use over X acres)
Prevalence of fungicide resistance occurring in your sphere of responsibility (X growers who have reported it, X vineyards tested positive, etc.)
Adoption of cultural practices (e.g., Y trellis system) that could help reduce occupational exposure (e.g., % of acres, growers who have adopted new practice)
Survey data conducted from growers and grower meetings on the value of mancozeb
Economic impact analysis relative to disease control and mancozeb in particular (e.g., $ losses suffered when DM or phomopsis went unchecked one year)
Export/import impacts (e.g., MRL/tolerances issues)
Changing weather patterns (e.g., climate change impacts in your region) (e.g., we have experienced X more damaging weather events in Y years than the previous decade)
Extension or otherwise bulletin where mancozeb is the recommended as standard treatment (e.g., mancozeb is recommended in our spray guidelines for X growers who interact with us)

What other PIDs has the EPA released relevant to grape?
As of April 30, 2024, the EPA proposed to ban the use of ziram in grape (EPA-HQ-OPP-2015-0568-0111). The EPA is currently reviewing comments received on this decision.

As of April 30, 2024, the EPA (EPA-HQ-OPP-2013-0296-0339) proposed to extend the REI for captan and reversed its previous decision to reduce the maximum application rate.

For table grapes: 5-day REI for girdling and turning for grapes grown on T-shaped trellises, no changes to REI for table grapes grown on Y-shaped trellises.
For wine and juice grapes: 3-day REI for high-contact activities, including tying and training vines as well as hand harvesting and leaf pulling.

The EPA reversed its previous decision to reduce captan application rate in grape because of stakeholder comments it received: “Stakeholder comments mentioned the need to maintain the 2 lbs. AI/A application rate for Eastern wine grapes for effective pest control. The comments also mentioned viticulture practice of applying captan to wine grapes early in the season because it interferes with fermentation. Therefore, EPA is proposing longer REIs for wine and juice grapes (rather than reducing application rates). Although these proposed activity-based REIs for grapes result in MOEs less than the LOC of 100, these longer REIs will address most risk concerns for re-entry workers exposed to captan on foliage.”

And if mancozeb is delisted…
What other products are available to control phomopsis, downy mildew and black rot in lieu of mancozeb? Dave Combs, a research support specialist in the Grape Sensing, Pathology and Extension lab at Cornell AgriTech, published this guide to what grape disease management will look like in a post-broad-spectrum world earlier this year.

Dr. Kaitlin (Katie) Gold is an Assistant Professor of Grape Pathology at Cornell University. She holds the primary research and extension responsibilities for grape disease management for New York State and leads the Grape Sensing, Pathology and Extension lab at Cornell AgriTech (GrapeSPEC).

*Editor’s note: For inspiration on what to write in your own formal comments to the EPA, consider this sample letter. See also this excellent report from The Ohio State University Extension Fruit Pathologist Melanie Lewis Ivey.