Propionic acid is probably the most commonly used hay preservative when baling wetter hay to prevent mold and spoilage. Being that propionic acid is a registered pesticide, the custom baler must be certified and licensed as a commercial applicator in the Field & Vegetable Crops category. A farmer also may custom bale hay using propionic acid up to the allowable limits of 3 different producers or 500 acres in any calendar year; if either limit will be exceeded, the farmer must get certified and licensed as a commercial applicator in the Field & Vegetable Crops category.

 

Other products also have been or are being used as a baled hay preservative. One is called Hay Guard that contains a combination of sulfur compounds as its active ingredients. It doesn’t contain propionic acid and doesn’t have an EPA registration number. As a consequence, the question was asked whether a custom applicator needs to be certified or licensed to apply Hay Guard. Although it doesn’t contain a pesticide, the manufacturer of Hay Guard is making pesticidal claims – and the product is NOT registered for use in Wisconsin. As a result, the WDATCP will place a ‘stop sale’ order on Hay Guard at known points of sale. The bottom line is that any applicator, private or commercial, using Hay Guard is making an illegal application.

 

Another product is Preservor and it too does not contain propionic acid. However, this product is a bit more interesting because it contains the active ingredient potassium sorbate which is on EPA’s 25(b) list of minimum-risk pesticides. Such pesticides are exempt from EPA registration and, therefore, can legally be used as pesticides even though none will have an EPA registration number. A detailed description of 25(b) pesticides can be found at: http://www.epa.gov/PR_Notices/pr2000-6.pdf

 

So far, so good with Preservor. Now, for the rest of the story. Wisconsin requires all pesticides, even 25(b) products, to be registered in Wisconsin. Unfortunately, the manufacturer and or distributer of Perservor has not yet done that. So, although a legal product in the eyes of EPA, it is illegal to use in our state unless registered. So, if you know the point of sale or supplier of Preservor, inquire whether their product is registered to ensure a legal sale to farmers. Also note that applicators of 25(b) products are subject to all use-regulations in WI as they are when applying any other pesticide.