No. 6/May 1, 1998
What's in a Name: Allegiance Seed Treatment
Gustafson, Inc., has introduced Allegiance, a fungicide seed treatment containing metalaxyl for use on a wide range of crops, including corn and soybeans. It is specifically designed to control early season fungal seedling blights (such as Pythium) and the seedling blight phase of Phytophthora. It is not effective against other seedling blight fungi.
If the previous paragraph sounds similar to a description of the seed treatment known as Apron, that is correct. The name Apron and the active ingredients for this fungicide have gone through some intriguing twists over the last 15 or so months. A "new" Apron (called Apron XL) from Norvartis contains mefanoxam as the active ingredient (not metalaxyl). There is Allegiance from Gustafson, which contains the active ingredient metalaxyl (but no longer marketed as Apron). And there are some existing stocks of the original Apron, which are still marketed as Apron. Confused? So was I.
The Apron/Allegiance story was brought to my attention by an astute seedman named Larry Hedgecock of Merschman Seeds, who called requesting information on Allegiance. After some searching, I somewhat untangled the names and suppliers of these fungicides.
As a part of its research and development program, Norvartis (formerly Ciba Agricultural) scientists isolated the primary active isomer (chemical molecule) in metalaxyl, which was given the common name mefanoxam. This product came to market as Apron XL, a fungicide with activity against Pythium, seedling Phytophthora, and downy mildew fungi. Because this product would have directly competed with metalaxyl (sold as Apron--as well as cause confusion in the market--Norvartis sought to cancel all registrations of metalaxyl. Because a number of other seed treatment formulators and sellers had a market share with Apron (metalaxyl), a product shown to be highly effective, Gustafson sought to have this cancellation overturned, citing economic as well as competitive disadvantages if only one company controlled the entire market for Pythium/Phytophtora seed treatments. They were successful, and metalaxyl is now being produced by another company.
So what does all this mean? Currently, there are three liquid formulations of fungicides with specific activity against Pythium and seedling Phytophthora (soybeans only) for use on soybeans and corn. Norvartis markets Apron XL (mefanoxam), Gustafson markets Allegiance (the original Apron containing metalaxyl, now renamed), and there still are some dealer stocks of the fungicide formerly known as Apron (metalaxyl). The stocks of Apron may be used until they are depleted.
When selecting one of these fungicides for soybeans, be sure and read the label for the proper application rate. Apron XL is applied at 0.32 to 0.64 fluid ounce per 100 pounds of seed. Allegiance and Apron are applied at 0.75 fluid ounce per 100 pounds of seed. All three products provide control of Pythium and seedling blight Phytophthora. Seed treatment trials have shown stand improvements and a slight yield improvement (1 to 3 bushels) with metalaxyl. I have not been provided Apron XL for inclusion in yearly seed treatment trials, so I can't offer information on how well it performs compared to Allegiance or Apron. I know thelatter products provide excellent protection against Pythium, a fungus active at cool (55 to 63 degrees F) temperatures and in wet soils, as well as control of early season Phytophthora. Always apply a cofungicide with Apron XL, Allegiance or Apron to provide protection against other seedling blight fungi. These products have no activity on Rhizoctonia or Fusarium.
H. Walker Kirby (email@example.com. uiuc.edu), Extension Plant Pathology, (217)333-8414