MS and TX both issued Section 18 "emergency use exemptions" for specific diuron formations; but ONLY for use in "commercial" catfish and striped bass production operations, and ONLY at the rate of 1/2-oz per acre-foot of water to control Giosmin (a specific algae that causes "muddy" off-flavor in catfish. The emergency-use exemption also allowed a maximum ANNUAL dosage of 4.5 oz of product per acre-foot.
The Section 18 emergency exemption DID NOT apply to private, recreational fishing, livestock or ornamental ponds (or any pond from which I will knowingly consume the fish).
I'm unsure if either Section 18 remains in effect today. Regardless, I personally declined many opportunities to sell diuron into that sector since I wanted no involvement in the matter - especially 10, 15 or 20 years down the road.
I've heard through the industry that there were several compelling reasons why DuPont (the original patent-holder) never pursued a Federal registration for diuron's use in aquatics - which, by the way, did NOT include the lack of potential profitability. I'll leave it at that.
Let's just say that when something threatens a major state-industry, that industry and their affiliated lobbyists may elect to use political leverage to secure a remedy.
Bottom line: There's a huge difference between EPA "pesticide registrations" and "Section 18 Emergency-Use Exemptions" - and that difference usually involves a shortfall in supportive data for the non-registered product's proposed "emergency use".
Lastly, please cite where you read that Canada allows the use of diuron in ponds. That revelation would utterly astonish me.
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I have been reading these posts, and I am surprised no one has mentioned that Canada allows the use of Karmex in ponds, or that Miss. has recommended the use in catfish ponds since 2005, as seen in this:
Jun 13, 2005 Delta Farm Press
COMMENTS 5
Mississippi Agriculture Commissioner Lester Spell recently announced his department has received approval from the United States Environmental Protection Agency for an emergency exemption on the herbicides Direx 4L and Karmex DF (both diuron) to control blue-green algae in catfish ponds.
�Our effort to make these diuron products available as pond management tools is vital to the health of our catfish industry as it gives producers the needed tools for controlling blue-green algae, a primary cause of off-flavor,� Spell said.
Mississippi catfish producers must balance their need to control blue-green algae with the desire to preserve pond plants that provide oxygen and keep water clean.
Several copper-based algaecides registered for use in catfish ponds are non-selective and have the potential to kill both beneficial plants and non-beneficial plants in ponds.
Direx 4L and Karmex DF are selective herbicides and target the primary pest plants responsible for off-flavor. The species of blue-green algae responsible for significant off-flavor problems in catfish is
Oscillatoria chalybea. This species releases a chemical compound known as MIB (2-methylisoborned) into the water.
Catfish absorb MIB into their bloodstream as water passes through their gills. The compound is transported by the blood and deposited into the flesh of the fish.
Low concentrations of MIB produce a musty-to-muddy off-flavor color, which inhibits the marketability of the fish.
Producers incur considerable costs holding affected catfish in ponds for several weeks until the fish purge the compound from their bodies.
The department has authority under Section 18 of the Federal Insecticide, Fungicide and Rodenticide Act to obtain an emergency exemption for a non-labeled useof a pesticide if significant losses of an agricultural commodity are likely and alternative, registered products are not available or effective.
The department administers the provisions of emergency exemptions through the Bureau of Plant Industry.
Catfish producers with questions can call the bureau toll-free at 888-257-1285.
I do have friends that use this, a little goes a long way, and have had no problem with it. It is not legal, but there you go.
