Updates on Chlorpyrifos Uses in 2022

Mar 11, 2022

By Ashley Dean and Erin Hodgson

Chlorpyrifos (e.g., Lorsban and Warhawk) is an organophosphate (Group 1B) insecticide that has been used for many important field crop pests in the United States. In the past 15 years, chlorpyrifos, like many organophosphates, has come under scrutiny due to acute toxicity concerns to humans, especially children. In an effort to protect all ages of humans and the environment, EPA began the process of phasing out many uses of organophosphates. On August 18, 2021, the EPA announced their decision to revoke tolerances for chlorpyrifos.

As of February 28, 2022, the EPA has revoked all food tolerances for chlorpyrifos. This means there is no longer any allowable chlorpyrifos residue for food products where chlorpyrifos was applied on or after February 28, 2022. Farmers may no longer apply pesticide products containing chlorpyrifos on crops grown for any food or feed use.

List 1 shows commodities for which uses are impacted by tolerance revocation. In Iowa, the relevant field crop uses that are impacted include: alfalfa, corn (field, sweet, and any for seed), soybean, sorghum, and wheat, as well as seed treatments. The list includes livestock uses and many horticultural crops that may be grown in field or greenhouse settings within Iowa, so please check the list in case your operation includes such commodities. See List 2 for a list of commodities that are not impacted by tolerance revocation. This list includes ear tags for cattle so long as certain conditions are met.

Common Questions:

Why revoke this insecticide? This decision follows a lengthy evaluation of the safety of chlorpyrifos from exposure via food, drinking water, and residential uses. EPA’s evaluation suggests that currently registered uses may exceed a safe level of exposure and likely cause adverse side effects, especially to children.

For what uses have tolerances been revoked? All tolerances have been revoked for food uses, including feed (List 1). Currently, non-food uses are still allowed, but the registration review process is ongoing, and EPA will decide soon about the remaining uses of chlorpyrifos. Sometimes, food crops also have non-food uses. EPA provides some examples of such commodities and relevant restrictions in a set of frequently asked questions.

What to do if you are in possession of chlorpyrifos products: If you have products containing chlorpyrifos in your possession, do not use these products on food or feed crops going forward.

After February 27, 2022, any chlorpyrifos products with food uses on the label are considered “misbranded,” and it is illegal to sell and distribute those products.
Labels will need to be amended to remove food uses that were cancelled when tolerances were revoked.

Disposal: Do not dispose of chlorpyrifos products in landfills. Currently, the state of Iowa does not have a plan for disposal of chlorpyrifos products. Therefore, it is best to either use these products according to the label for non-food uses only or store them until appropriate disposal opportunities are available.

Enforcement: FDA has a 2-stage enforcement approach if chlorpyrifos residues are detected in food products on or after the revocation date (February 28, 2022). This is because chlorpyrifos residues from legal applications made prior to the revocation date may be present in trade channels for different periods of time (i.e., showing dates) depending on application and harvest dates and the duration of storage, distribution, and sale. During Stage 1, companies will not be asked to provide documentation of legal applications when residues are found below the previous tolerance level. After the showing dates, Stage 2 is implemented and documentation of purchase or spraying records may be required when chlorpyrifos residues are found in food products. FDA anticipates that all food made from commodities with legal applications of chlorpyrifos will exit the trade channels by August 28, 2026. To see a list of showing dates see the FDA Q&A document (page 9).

Since several aspects of this decision remain unclear, including disposal of products and whether non-food uses will continue after the registration review process is complete, we intend to post timely updates on ICM News as we learn more. If you would like more information, see the list of resources below.

List 1. Uses impacted by tolerance revocation.
Chlorpyrifos cannot be used for these commodities after February 27, 2022.

Field and Greenhouse Food Crops*

Alfalfa
Asparagus
Banana
Bean (snap, lima)
Beet (sugar, table, for seed)
Blueberry
Brassica leafy vegetables, radish (incl. for seed), rutabaga, turnip
Caneberry
Cherimoya
Citrus and citrus orchard floors**
Corn (field, sweet, for seed)
Cotton
Cranberry
Cucumber
Date
Feijoa
Fig
Grape
Kiwifruit
Leek
Mint
Onion (dry bulb)
Pea
Peanut
Pepper
Pumpkin
Sapote
Seed and pod vegetables
Seed treatments
Sorghum (grain, milo)
Soybean
Strawberry
Sugarcane
Sunflower
Sweet potato
Tree fruits (apple, cherry, nectarine, peach, pear, plum, prune)**
Tree nuts (almond, filbert, pecan, walnut)**
Wheat

Livestock

Cattle ear tags***
Poultry houses
Turkey, swine, and dairy barns

*Remember to keep adequate records of chlorpyrifos applications to any of these crops for food or non-food usage in case EPA asks for production of these records. See “Enforcement” section.

** Unless made to non-bearing trees that will not bear fruit within a year.

*** Except beef and non-lactating dairy cattle and cattle in mating and cow-calf operations if ear tags are removed >1 year prior to slaughter. Remember to keep adequate records of ear tag usage.

List 2. Uses NOT impacted by tolerance revocation.
Chlorpyrifos can still be used on these commodities after February 27, 2022.

Christmas tree plantations
Commercial ornamentals
Commercial sod farms
Containerized baits
Fence posts, logs, poles
Food processing plants
Forest tree nurseries and plantations; felled trees; cut stumps
Golf courses
Grass sown for seed
Individual fire ant mounds
Industrial plants
Landscape timbers
Manufacturing plants
Mosquito control
Non-bearing fruit, nut, or citrus trees
Railroad box cars
Railroad ties
Road medians
Ship holds
Turf and ornamentals in road medians or industrial sites
Underground utility cables and conduits
Warehouses
USDA quarantine in nurseries and greenhouses (i.e., soil treatment of containers)
Tobacco

Source : iastate.edu

Video: Turning Plant Defense Into a Management Strategy

Turning Plant Defense Into a Management Strategy

Understanding how a plant responds to stress is one thing.

Using that knowledge to make better management decisions is another.

Systemic acquired resistance, or SAR, is the plant's more direct defense response. When stress or infection occurs, the plant begins signaling throughout its system and preparing defensive compounds.

But if we know that response exists, can we help prepare the plant before the stress arrives?

The answer starts with understanding what triggers the response and what the plant needs to carry it out.

The Trigger and the Fuel

Salicylic acid plays an important role in triggering the SAR pathway.

Think of it as turning the truck on.

The engine may be running, but it still needs fuel to do the work.

In this case, manganese plays an important role in supporting the enzyme systems involved in the plant's defensive response.

This makes manganese status an important part of the conversation. Whether a producer is using tissue testing, sap analysis, or simply scouting for visible deficiency symptoms, the goal is to make sure the plant has adequate manganese available.

Manganese is required in relatively small amounts, but that does not make its role small.

If the plant receives a signal to defend itself but lacks the nutrition needed to support that response, it may struggle to carry out the process efficiently.

The trigger matters.

The fuel matters too.

Prepare Before the Stress Arrives

The best time to think about stress management is before the plant is overwhelmed.

Once a crop is already struggling, management can quickly turn into a game of catch-up.

This is similar to nitrogen management. Once a plant becomes severely deficient, correcting the problem does not necessarily erase the time and yield potential already lost.

Plant defense can work the same way.

Low-rate, targeted approaches designed to support the SAR pathway may fit best ahead of an expected stress event rather than after significant damage has already occurred.

That requires producers to think about predictable stress.

We may not know exactly what the weather will do tomorrow, but we generally know summer heat is coming. We know certain field conditions increase disease pressure. We know a herbicide application can temporarily stress a crop as the plant processes the chemistry.

Even a properly timed and labeled herbicide application can create a temporary response in the plant.

That does not mean the herbicide is bad.

Weeds can create significantly more yield loss than the temporary stress caused by controlling them.

The question is not whether we should eliminate every stressor.

The question is whether we can better prepare the plant to manage necessary and predictable stress.

Not All Stress Is Bad

Stress is a normal part of plant growth.

A perfectly stress-free environment does not exist in the field.

In fact, some stress is necessary for normal plant development. A plant responds to wind, temperature, moisture, sunlight, and countless other environmental signals throughout the season.

The environment is stress.

The plant's job is to manage it.

Problems begin when the stress load becomes greater than the plant's ability to respond.

Extreme heat, drought, high salt concentrations, disease pressure, and even certain management practices can add to that load.

This is where understanding SAR becomes useful.

Instead of waiting until the plant is visibly struggling, producers can begin identifying periods when stress is likely and make management decisions around those windows.

ISR Starts With the Soil

While SAR is a more direct defense response, induced systemic resistance, or ISR, brings the conversation back to soil health.

The longevity of a farm is closely connected to the health of its soil.

Carbon plays a major role because it supports biological life within the soil. Bacteria, fungi, and other organisms interact with plant roots and influence how the plant grows, accesses nutrients, and prepares for stress.

This is why soil health cannot be reduced to one product or one application.

It is a system.

Keeping living plants in the field longer can support biological activity. Cover crops may fit some operations. Better water management can improve soil conditions.