Specialty crop and minor-use pesticide prioritization at the 2023 IR-4 Food Use Workshop

Nicole Soldan, Michigan State University Department of Horticulture, and John Wise, Michigan State University Department of Entomology - October 09, 2023

Participants at the 2023 IR-4 Food Use Workshop identified the most important research projects for the 2024 IR-4 food-use research program.

The IR-4 Project (Interregional Research Project No.4) facilitates the registration of sustainable pest management technology for specialty crops and minor uses. Since 1963, the IR-4 Project has been the major resource for supplying pest management tools for specialty crop growers by developing research data to support new Environmental Protection Agency (EPA) tolerances and labeled product uses. Specialty crop research needs are prioritized each year during a national workshop since resources are limited (quoted from the IR-4 web).

Research priority A’s for the year 2023 field program for fruits, vegetables, nuts, field and oil crops, herbs and other miscellaneous crops in the United States and Canada were selected at the Food Use Workshop held Sept. 12–14, 2023, in Raleigh, North Carolina. About 170 people attended the three-day meeting, 133 in-person and 33 virtually, including specialty crop researchers, Extension specialists, representatives of commodity and industry groups across the country, and personnel from EPA, United States Department of Agriculture (USDA), IR-4 plus the Agriculture and Agri-Food Canada (AAFC) that conducts Canadian counterpart of minor use program, and Pest Management Regulatory Agency (PMRA), i.e., Canadian counterpart of U.S. EPA.

For Michigan’s fruit and vegetable interest, the workshop was attended in person by Michigan State University’s Nicole Soldan, John Wise, Mary Hausbeck, Timothy Miles and Celeste Wheeler. Representing north-central region commodity liaisons were Pete Nelson of the Michigan Cherry Committee and Bob Kaldunski of the Wisconsin Ginseng Association.

The prioritization process focused on the most critical pest management needs from all disciplines, for each commodity. Participants were provided with a list of 239 projects nominated with desired priority of A prior to the food-use workshop. As a group, they ranked products based on availability and efficacy of alternative pest management tools (including ongoing projects for the same need and resistance management), damage potential of target pest(s), performance and crop safety of the chemical in managing the target pest(s), compatibility of the proposed chemical candidate with integrated pest management, uses currently covered by Section 18 emergency exemptions, and harmonization implications due to lack of international MRLs (Maximum Residue Limits).

Based on projected budget appropriations for IR-4 in 2023, only 39 A priority projects throughout the disciplines were selected by consensus. An A priority guarantees IR-4 to begin the field residue program during the following season and complete it within 30 months. The timeline will be shortened when IR-4 joins the company’s petition submission schedule with the expectation that a complete data package be submitted to the EPA in 16-24 months.

In addition to the above projects that require pesticide residue analysis under GLP, 10 H+ (high priority plus) efficacy/crop safety projects have been selected, because potential registrants want to see the data first before IR-4 conducts full residue studies, or IR-4 needs to screen pest control products for new pests, the PPWS (pest problems without solution) projects.

Nineteen priority projects important for Michigan were selected and five projects have been upgraded to A priority status through the priority upgrade process (PUP) (Table 1). In addition, nine candidate H+ projects for Michigan growers were identified (Table 2). Any additional B priority projects must be upgraded to A priority either by PUP with good justification or regional upgrade, i.e., the crops or the pests are limited to a particular region. At present, IR-4 may consider eight upgrades should the budgetary situation become more favorable.

The following new candidate priority A and H+ projects listed are preliminary until affirmed at the IR-4 national research planning meeting on Oct. 25 – 27, 2023. A complete listing can be found on the IR-4 website.

Table 1. Priority A projects for Michigan fruits and vegetables.
Group	Commodity	Chemical	Reasons for need
02	Beet greens (garden)	Zeta-cypermethrin	Aphids, thrips, and armyworms. This chemical is currently registered for garden beet roots, but is not registered for beet greens.
03-07B	Onion (green)	Linuron	New tools are needed for management of emerged weeds, which are especially competitive in young onions.
04-16A	Lettuce (greenhouse transplant)	Azoxystrobin	Soil-borne pathogens; growers have struggled to control root rots on vegetable transplants without fungicide tools.
05-16	Broccoli	Mefentrifluconazole	Alternaria leaf spot; due to limited available chemistries, the risk of pathogen resistance to the limited modes of action is considerably large.
08-10A	Tomato (greenhouse)	GF-4031	Powdery mildew; rotational product for resistance management, this product is a unique FRAC group.
08-10BC	Pepper (bell and non-bell) (greenhouse)	Pyridaben	Whiteflies, mites
08-10BC	Pepper (greenhouse)	GF-4031	Powdery mildew; rotational product for resistance management, this product is a unique FRAC group.
09A	Cantaloupe	Flumioxazin + pyroxasulfone	Broadleaf and grass control with a special emphasis on ragweed parthenium.
09B	Cucumber	Flumioxazin + pyroxasulfone	Broadleaf and grass control with a special emphasis on ragweed parthenium.
09B	Cucumber (greenhouse)	GF-4031	Powdery mildew; rotational product for resistance management, this product is a unique FRAC group.
09B	Squash (summer)	Flumioxazin + pyroxasulfone	Broadleaf and grass control with a special emphasis on ragweed parthenium.
12-12A	Cherry	Fluopicolide	Phytophthora species causing root and crown rot.
12-12B	Peach	Oxathiapiprolin	Phytophthora root rot, crown, and trunk diseases; alternatives to phosphite are needed because of over usage and the detection of phosphite resistance in some species.
12-12C	Plum	NAA	Rootstock suckers, basal trunk sprouts. Need for systemic long-lasting product to suppress sucker growth and reduce number of contact herbicide sprays and hand labor.
12-12C	Plum	Oxathiapiprolin	Phytophthora root rot, crown, and trunk diseases; alternatives to phosphite are needed because of over usage and the detection of phosphite resistance in some species.
13-07B	Blueberry	Flutriafol	Mummy berry, stem blight pathogens, anthracnose.
13-07B	Blueberry	Tolpyralate	Pigweeds, lambsquarters, crabgrass, Italian ryegrass.
13-07G	Strawberry (greenhouse transplant)	Mefenoxam	Phytophthora root rot
13-07G	Strawberry (greenhouse)	Isofetamid	Powdery mildew, gray mold, anthracnose; need additional labeled products for greenhouse control; important for resistance management.
03-07AB	Onion	Cyclaniliprole	PUP – additional tool to control thrips
25AB	Mint	Linuron	PUP – red root pigweed and other weed control
05-16	Cabbage	Mefentrifluconazole	PUP – control of alterneria leaf spot
13-07G	Strawberry	AC203	PUP – control of botrytis fruit rot
04-16A	Swiss chard	Ethofumesate	PUP – control of annual broadleaves and grasses

Table 2. High priority needs for efficacy/crop safety projects for Michigan fruits and vegetables.
Group	Commodity	Chemical	Reasons for need
03-07A	Onion (dry bulb)	Pyraflufen-ethyl	Annual weeds. Dry bulb onions lack significant chemical tools for the management of emerged weeds.
06-22A	Bean (snap)	Isocycloseram	Seed corn maggot; replacement for chlorpyriphos.
06-22CE	Bean, lima (succulent and dried shelled)	Pyroxasulfone	Currently, pyroxasulfone labels do not allow for rotating to lima beans the following season. In addition, pyroxasulfone is highly effective on amaranthus species to allow farmers to achieve effective weed control prior to planting lima beans and improve overall weed control.
06AB	Pea (edible podded and succulent shelled)	Pyridate	Broadleaf weeds. Pyridate has shown to be an effective tool for controlling lambsquarters and could be a valuable tool for managing this early emerging species in peas.
08-10BC	Pepper (non-bell)	Sulfentrazone	Weeds, nutsedge, annual morning glory.
09A	Cantaloupe	Isocycloserum	Seed corn maggot; replacement for chlorpyriphos.
12-12A	Cherry	1-aminocyclopropane-1-carboxylic acid (ACC)	Flower fruit thinning, reduce labor costs for thinning flower and fruit using a natural product.
13-07B	Blueberry	Fluroxypyr	Dogbane, horsetail, bindweed, buckwheat, common mallow. Alternative to reluctantly used 2,4-d and glyphosate.
13-07G	Strawberry	Flazasulfuron	Yellow nutsedge, broadleaf weeds, annual grasses, lack of alternatives.

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