Management of Italian Ryegrass (Lolium perennessp.multiflorum) in Western Oregon with Preemergence Applications of Pyroxasulfone in Winter Wheat

Abstract

Management of Italian ryegrass in cereal-based cropping systems continues to be a major production constraint in areas of the United States, including the soft white winter wheat producing regions of the Pacific Northwest. Pyroxasulfone is a soil-applied herbicide with the potential to control broadleaf and grass weed species, including grass weed biotypes resistant to group 1, 2, and 7 herbicides, in several crops for which registration has been completed or is pending, including wheat, corn, sunflower, dry bean, and soybean. Field experiments were conducted from 2006 through 2009 near Corvallis, OR, to evaluate the potential for Italian ryegrass control in winter wheat with applications of pyroxasulfone. Application rates of PRE treatments ranged from 0.05 to 0.15 kg ai ha−1. All treatments were compared to standard Italian ryegrass soil-applied herbicides used in winter wheat, including diuron, flufenacet, and flufenacet + metribuzin. Visual evaluations of Italian ryegrass and ivyleaf speedwell control and winter wheat injury were made at regular intervals following applications. Winter wheat yields were quantified at grain maturity. Ivyleaf speedwell control was variable, and Italian ryegrass control following pyroxasulfone applications ranged from 65 to 100% and was equal to control achieved with flufenacet and flufenacet + metribuzin treatments and greater than that achieved with diuron applications. Winter wheat injury from pyroxasulfone ranged from 0 to 8% and was most associated with the 0.15–kg ha−1application rate. However, this early-season injury did not negatively impact winter wheat yield. Pyroxasulfone applied at the application rates and timings in these studies resulted in high levels of activity on Italian ryegrass and excellent winter wheat safety. Based on the results, pyroxasulfone has the potential to be used as a soil-applied herbicide in winter wheat for Italian ryegrass management and its utility for management of other important grass and broadleaf weeds of cereal-based cropping systems should be evaluated.

Winter Wheat Response to Weed Control and Residual Herbicides

“…Pyroxasulfone's soil residual activity and utility have allowed it to be registered for multiple uses including corn (field, sweet, and pop) (Zea mays L.), soybean, cotton, fallow land, and non-crop areas [47][48][49]. Winter wheat tolerance has been well documented with only minor injury in the form of stunting with no negative effects on yield [50][51][52]. With PRE soil activity on broadleaf and grass species including ALS- [52], ACCase- [41], and glyphosate- [1] resistant Italian ryegrass biotypes, pyroxasulfone use in wheat will afford growers an early season weed control option that was previously unavailable.…”

“…The soils for the present studies were a sandy loam, loamy sand, or sandy clay loam with less than 2.0% organic matter. Hulting et al [52] noted 3% or less wheat injury from pyroxasulfone rates up to 100 g ha −1 on a silt loam soil. Previous research indicated decreased pyroxasulfone injury with legumes grown in soils with greater clay contents [19].…”

Peanut Cultivar Response to Preemergence Applications of Pyroxasulfone

“…Pyroxasulfone applied at rates between 60 and 180 g ai/ha has been documented to control: Amaranthus spp., Lolium spp., Urochloa spp., goosegrass (Eleusine indica L.), crowfootgrass (Dactyloctenium aegyptium L), and Digitaria spp. (Geier et al 2006;Hulting et al 2012;King and Garcia 2008;Koger et al 2008;Knezevic et al 2009;Nurse et al 2011).…”

“…Pyroxasulfone use in corn, cotton (Gossypium hirsutum L.), soybean, and wheat (Triticum aestivum L.) tolerance has been thoroughly described (Cahoon et al 2012;Eure et al 2013;Geier et al 2006;Hulting et al 2012;King and Garcia 2008;Koger et al 2008). However, very little is known concerning peanut response to pyroxasulfone following PRE applications.…”

Peanut Response to Postemergence Application of Pyroxasulfone

“…Pyroxasulfone provides residual control of troublesome annual broadleaf weeds and grasses, including; browntop millet (Urochloa ramose L.), barnyardgrass (Echinochloa crus-galli L.), green foxtail (Setaria viridis L.), Amaranthus spp., velvetleaf (Abutilon theophrasti Medik. ), large crabgrass (Digitaria sanguinalis L.), Italian ryegrass (Lolium multiflorum L.), and kochia (Kochia scoparia L.) (Geier et al 2006;Gregory et al 2005;Hulting et al 2012;King and Garcia 2008;Koger et al 2008;Nurse et al 2011). Pyroxasulfone applied at 209 g ai/ha controlled broadleaf signalgrass (Urochloa platyphylla L.) similar to dimethenamid-p and S-metolachlor; however, dimethenamid-p and S-metolachlor provide poor residual control of Texas millet (Urochloa texana Buckl.)…”