HRS WHEAT VARIETY TOLERANCE TO TRIFLURALIN GRANULES.

Currently, a common question is wheat variety tolerance to preplant-incorporated (PPI) trifluralin granules. PPI trifluralin granules may be spring applied at 3.5 to 4 lb/acre for foxtail suppression in hard red spring (HRS) wheat only west of Highway 3 in North Dakota. Tolerance of recently-released HRS wheat varieties to spring-applied, PPI trifluralin granules was tested in a NDSU trial conducted in 1997-98 at Carrington and Cass County. This application strategy and the locations were chosen because of greater wheat injury potential and the subsequent usefulness in testing wheat variety tolerance. Adequate soil moisture or rainfall after granule application may quickly activate the majority of the herbicide=s active ingredient. If the activated herbicide is present at a high level in the soil zone where the emerging wheat shoot is present, plant injury likely will occur.

In the trial, Treflan granules were applied at 4 lb/acre and 13 HRS wheat varieties planted 1 to 2 weeks later at 1.2 to 1.3 million pure live seeds/acre. Varieties tested included: 2375, AC Barrie, AC Cora, Butte 86, Gunner, Hamer, Keene, Kulm, Lars, Oxen, Russ, Trenton, and Verde. Plant stands were evaluated for injury and stand loss at the 1.5-to 2-leaf stage. Significant injury occurred at three of four locations due primarily to substantial rainfall after granule application. Across locations and years, stands were reduced an average of 25 to over 40% with trifluralin granules compared to the untreated check. While substantial stand reduction occurred with trifluralin, the remaining plants generally compensated for the lower density. Grain yield was unaffected among most varieties tested, when averaged across locations and years.

If using PPI trifluralin granules in wheat, consider the following to minimize crop injury: choose varieties with adequate trifluralin tolerance and seed vigor, use good-quality seed, use a pure live seeding rate of at least 1.25 to 1.5 million seeds/acre, and seed at about a 1.5-inch depth (avoid deep planting). Consult herbicide labels for specific use instructions.

OVERVIEW OF NEW HERBICIDE LABELS IN 2000

The following is a selected listing of relatively-new herbicides labeled for use in 2000 (as of April 20). Refer to herbicide labels and the 2000 ND Weed Control Guide for details on use.

Canola:

*Liberty - Section 3 label for weed control only in Liberty-resistant canola. Post-emergence control of annual broadleaf weeds, and control or suppression of annual grasses and perennial weeds.

*Muster - Section 18 label for wild mustard control in canola grown only for seed.

*Raptor - Section 18 label for wild mustard control only in Clearfield (IMI-resistant) canola. Post-applied herbicide that provides broad-spectrum control of annual grasses and broadleaf weeds.

*Sonalan - Section 18 label for ALS-resistant kochia.

*Stinger - Section 18 label for Canada thistle and perennial sowthistle control. Post-emergence herbicide that also controls several annual broadleaf weeds.

Chickpea:

*Select - Post-emergence control of annual grass and quackgrass.

*Sonalan - PPI control of annual grasses and selected broadleaf weeds.

*Tough - ND 24C label for selected annual broadleaf weeds including cocklebur, kochia, lambsquarters, nightshade species, pigweed species, and Russian thistle.

Corn:

*Celebrity Plus - Commercial tank mixture of Accent plus Distinct for broad-spectrum grass and broadleaf control.

Crambe:

*Sonalan - ND 24C label for annual grass and selected annual broadleaf control.

Dry bean:

*Raptor - Section 18 label for eastern black nightshade control. Post-applied herbicide that provides broad-spectrum control of annual grass and broadleaf weeds.

Flax:

*Curtail M - Section 18 label for Canada thistle and perennial sowthistle control. Post-emergence herbicide that also controls selected annual broadleaf weeds.

Small grain:

*Harmony GT - Post-emergence applied, sulfonylurea herbicide for broad-spectrum control of annual broadleaf weeds.

*Maverick - Downy brome, quackgrass, mustard species, and volunteer sunflower control only in winter and spring wheat. Rotation restrictions will limit use.

Soybean:

*Authority - Soil-applied herbicide for control of selected annual small-seeded broadleaf weeds.

*Domain - Soil-applied, commercial tank mixture of flufenacet plus Sencor for selected annual grass and broadleaf weed control.

*Extreme - Commercial tank mixture of Pursuit plus Roundup for broad-spectrum weed control only in Roundup-resistant soybean.

*Touchdown - Glyphosate product labeled for broad-spectrum weed control only in Roundup- resistant soybean.

Sunflower:

*Spartan - Section 18 label for kochia control. Soil-applied (PPI or PRE) herbicide for control of selected small-seeded, annual broadleaf weeds.