By Dustin Harrell & Don Groth, LSU AgCenter Rice Specialists
The current list of available fungicides is longer than ever but not all will be readily available nor useful this year. The QoI Strobilurin fungicides (Group 11) Quadris, Equation and Gem are good against the wild type sheath blight and blast, but poor against the strobilurin resistant sheath blight fungus, Cercospora and the grain smuts.
The Carboxamides fungicides (Group 7), Sercadis and Elegia, have good wild and strobilurin resistant sheath activity and some Cercospora activity but they have no blast nor smut activity. Elegia will be in good supply this year but Sercadis may be hard to find and more expensive.
The Demethylation Inhibitors fungicides (DHI) (Group 3) Tilt, Bumper, PropiMax and others are inexpensive and have good Cercospora and smut activity but are only weak against sheath blight and no have blast activity. There are several tank mixes of these active ingredients, Amistar Top, Quilt and Stratego, which combine the performance of the standalone products and have a very good fit in rice production.
Syngenta received a full federal label for the new rice fungicide Amistar Top last year. It is a pre-mix of azoxystrobin (Group 11) and difenoconazole (Group 3). The difenoconazole component has a different mode of action, the same as propiconazole, than the strobilurins or the DHI fungicides but is effective against the wild-type and fungicide-resistant sheath blight isolates. Unfortunately, it did not perform very well last year in the field for some unknown reason as compared to previous small plot results.