Managing Sunflower Pests in 2003
The herbicide Spartan™ (Sulfentrazone) has received another Section 18 Emergency label for use this year in most sunflower producing states. The FMC product has been available for the past four growing seasons and it is expected that EPA will grant a full Section 3 label sometime in 2003. The full label will permit Spartan to be applied in the fall, a beneficial option for many no-till sunflower producers, as that will permit a wider window of application.
Spartan is a pre-emerge herbicide for control of a number of annual small-seeded broadleaf weeds, such as kochia, pigweed species, lambsquarters, nightshade, smartweed, Russian thistle and biennial wormwood and some suppression of buckwheat, mustard, ragweed, and Russian thistle. Spartan may provide some grass but no perennial weed control.
The Section 18 exemption allows a single ground application of Spartan at a rate of 2.0 to 5.33 ounces of product per acre. The application must be made at least 14 days before or 3 days after planting. Use higher rates if applied up to 30 days prior to planting.
Sunflower has good tolerance to Spartan on medium to fine textured soils with organic matter above 3%. Crop injury may occur on soils with low organic matter and soil pH greater than 8.0. Do not use the product on coarse textured soils with less than 1% organic matter.
Research has shown excellent weed control in many different environments throughout the Great Plains region. However, consistent control of sensitive broadleaf weeds and control of grass and marginally susceptible broadleaf weeds greatly depends on at least 0.75 inches of rainfall shortly after application and before weeds emerge, according to North Dakota State University. Thus, consider applying Spartan well ahead of planting, up to two weeks beforehand.
Spartan is a PPO inhibitor mode of action herbicide, in which no weed resistance has been documented. Growers should keep in mind that poor growing conditions at and following sunflower emergence, cold temperatures, soil compaction, or application rate that’s too high based on soil type and organic matter may result in sunflower injury. Make sure furrows are closed at planting to help minimize injury.
Beyond Label Approved for Clearfield
Beyond™ (Imidazolinone) has received a full Section 3 label for use this growing season, exclusively on Clearfield™ sunflower. It may be used to control several broadleaf weeds, including common cocklebur and marshelder, on Clearfield sunflower. BASF developed the Clearfield technology, which is imazamox-resistant sunflower using conventional breeding.
Mycogen and Seeds 2000 are offering Clearfield sunflower hybrids this growing season. It’s expected that Clearfield sunflower will be more widely available to sunflower growers in the U.S. next year, with more companies offering Clearfield hybrids.
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