Lower pH for rice herbicides
Jun 1, 2009 9:37 AM,
By Bruce Schultz
LSU AgCenter
Rice growers heard advice from a range of LSU AgCenter experts during the recent southwest rice field. The event was held near Fenton, La., at research and demonstration plots on the farms of Jimmy Hoppe and Mark Pousson.
In one piece of advice, Eric Webster, LSU AgCenter weed scientist, said farmers should consider using ammonium sulfate to lower the pH of water used for mixing herbicides. Lower pH will often increase the activity of some herbicides, but some products can lower the pH to levels that could affect equipment. Webster prefers a pH in the neighborhood of 5.5.
Webster is doing work this year with the Ricebeaux herbicide as a possible alternative to Arrosolo, which will not be legal to use after this year. He said sales of Arrosolo were stopped last year.
Webster also cautioned farmers that medium-grain rice varieties and hybrids are more sensitive to injury from some herbicides. “That’s why we always use 2X rates in our studies, to simulate overlap.”
Webster recently viewed a field that had been planted in hybrids for three consecutive years. The volunteer rice from last year was widespread, he said, and that increases the possibility of outcrossing of herbicide resistance.
“There’s really only one choice — Roundup — (then) start all over and probably plant beans,” Webster said.
Farmers should start thinking about fungicide applications, Don Groth, LSU AgCenter plant pathologist. He said growers should consider the selection, amount and timing of the application. The boot stage is the best time for fungicides to be used against sheath blight.
Johnny Saichuk, LSU AgCenter rice specialist, said sheath blight has been found already this year in fields in Acadia Parish. “If you are in green ring or beyond, you need to be looking for sheath blight.”
Saichuk said the weather has caused problems for north Louisiana farmers. Rains have prevented some from finishing critical work, and a few have not yet finished planting.
