Sedges are increasingly resisting Mid-South rice growers’ attempts to control these troublesome weeds.
“Sedges have become a major weed control problem in rice production due to repeated use of the same modes of action, year after year,” says Chris McClain, market development specialist, Corteva Agriscience. “Growers’ product of choice for sedge control has primarily been ALS chemistry, which has led to resistance issues with several sedge species.”
Specifically, growers are fighting ALS-resistant (Group 2) populations of yellow nutsedge, annual flatsedge, rice flatsedge, smallflower umbrella sedge and, now, white margin sedge. The challenge is intensified for those operating a continuous rice production system or planting in zero-grade fields.
Amplifying the resistance challenge is the potential for reduced herbicide activation of soil-applied herbicides due to inadequate rainfall.
“If we aren’t able to get rainfall, sedges tend to break through preemergence treatments more easily than other grassy weed species,” McClain says. “Even if you flush a larger field to achieve herbicide activation, it’s difficult to get enough water across the entire field to activate your preemergence, especially on zero-grade fields.”
Yellow nutsedge continues to be the predominant sedge species in most rice fields, but other types of sedge are becoming more prevalent. Sedge escapes can quickly become an issue as population numbers can explode in a short time. While yellow nutsedge reproduces vegetatively through the production of new tubers, other sedges, including annual sedge, rice flatsedge and smallflower umbrella sedge, all reproduce through seed spread.
“They produce a lot of seed and they spread very quickly,” McClain says.
With control options limited, rice growers are discovering that Loyant® herbicide can effectively control ALS-resistant sedges.
Loyant® herbicide with Rinskor® active offers broad-spectrum control of broadleaf, grass, sedge and aquatic weeds. A full labeled rate of Loyant herbicide should be applied preflood to actively growing weeds.
To improve resistance management, McClain recommends including Loyant herbicide as part of a season-long weed control plan that includes multiple modes of action and overlapping residuals.
“Loyant is the tool of choice in fields with heavy sedge pressure,” McClain says. “Loyant offers rice producers a tool that fits very well into their cropping system, if timed properly. As a synthetic auxin, Loyant fits all rice production systems where ALS-resistant sedges are an issue and improves resistance management.”
Loyant® is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Rinskor® is a registered active ingredient. Always read and follow label directions.
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