By: Kathleen Hall (Research Scientist, Minnesota Department of Agriculture) & Bob Koch (Extension Entomologist, University of Minnesota)
In 2020, the Commissioner of Agriculture officially
designated two neonicotinoid insecticides, clothianidin and imidacloprid, as “surface
water pesticides of concern” due to detections of these active ingredients at
elevated levels in surface waters in Minnesota. To address water quality
concerns, the Minnesota Department of Agriculture (MDA), in coordination with
the University of Minnesota Extension, developed “Water Quality Best Management Practices for Agricultural Use of Clothianidin & Imidacloprid.” The best
management practices (BMPs) are designed to prevent the contamination of water
resources by clothianidin and imidacloprid from direct insecticide applications
as well as treated seeds.
Examples of promoted practices include:
•
Scouting fields regularly and using economic
thresholds to help determine if, when, and where to apply;
•
minimizing seed dust generation and drift by
avoiding planting treated seed during windy conditions (>15 mph) and when
the wind is blowing toward nearby waterbodies; and
•
maintaining grass or vegetation buffers near
tile inlets and in drainage ditches.
The water quality BMPs for agricultural use of clothianidin
and imidacloprid are a companion to the “Water Quality Best Management Practices for All Agricultural Insecticides.” The MDA has also developed
stewardship guidelines and BMPs for the general neonicotinoid class of
insecticides to protect insect pollinators. All pesticide BMPs are available on
the MDA’s
Pesticide BMPs webpage.
Use in Agriculture
In Minnesota, clothianidin (Poncho, Belay) and imidacloprid (Leverage
360, Gaucho) are used to manage insect pests on a variety of agricultural crops
including soybean, corn, sugar beet, and potatoes. Clothianidin and imidacloprid are also used in urban settings on sites such as residential
lawns, trees, and ornamentals. These insecticides can be applied through foliar
sprays, soil treatments, and chemigation, but they are particularly popular as
seed treatments.
Since their introduction in the 1990s, neonicotinoids have
become the most widely used class of insecticides in the world. While neonicotinoids
are useful tools for managing insect pests, chemicals in this class often have
properties, such as high solubility in water, that favor movement to nearby
waterbodies or groundwater. Neonicotinoids, including clothianidin and
imidacloprid, are highly toxic to aquatic invertebrates and have the potential
to cause negative effects at very low concentrations in rivers and streams.
Therefore, it is particularly important to take actions to prevent the
contamination of nearby waterbodies when using these insecticides.
Detections in Water
The MDA monitors waters throughout the state for over 180
pesticide compounds, including clothianidin and imidacloprid. Both insecticides
have been detected in groundwater and surface waters, such as rivers and
streams, in Minnesota. While concentrations in groundwater are low compared to human
health-based guidance values from the Minnesota Department of Health,
concentrations in rivers and streams have been found above the Environmental
Protection Agency’s chronic aquatic
life benchmarks for aquatic invertebrates. More information on surface
water detections is available in the following handout: “Detection
Patterns of Neonicotinoids in Minnesota Rivers and Streams, 2018-2022.” Annual
monitoring reports and additional information about the MDA’s monitoring
program can be found on the MDA’s
website.
Reference to commercial products or trade names is made with the understanding
that no discrimination is intended, and no endorsement is implied.
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