Winter annual grass control and crop safety in quizalofop‐resistant wheat varieties

AbstractDowny brome (Bromus tectorumL.) is a widely distributed invasive winter annual grass across western North America.Bromus tectorumphenology can vary considerably among populations, and those differences are considered adaptively significant. A consensus hypothesis in the literature attributes the majority of observed differences inB. tectorumphenology to differing vernalization requirements among populations. A series of greenhouse experiments were conducted to identify differences inB. tectorumvernalization requirements and link vernalization to expression of annual false-brome [Brachypodium distachyon(L.) P. Beauv.]-derived vernalization gene homolog (BdVRN1). Results from this study indicate that variation in time to flowering is partially governed by differing vernalization requirements and that flowering is linked to the expression ofBdVRN1.

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The Determinants of the Distribution and Abundance of the Winter Annual Grass Vulpia Ciliata ssp. Ambigua

Journal of Ecology ◽

10.2307/2261556 ◽

1995 ◽

Vol 83 (2) ◽

pp. 177 ◽

Cited By ~ 42

Author(s):

P. D. Carey ◽

A. R. Watkinson ◽

F. F. O. Gerard

Keyword(s):

Annual Grass ◽

Winter Annual

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Expansion of Feral Cereal Rye (Secale cereale L.) on Non-crop Hillsides in Northern Utah

Invasive Plant Science and Management ◽

10.1017/inp.2016.3 ◽

2017 ◽

Vol 10 (01) ◽

pp. 26-32 ◽

Cited By ~ 2

Author(s):

Kyle C. Roerig ◽

Corey V. Ransom

Keyword(s):

Early Detection ◽

Native Species ◽

Landscape Scale ◽

Annual Grass ◽

Cereal Rye ◽

Secale Cereale L ◽

Northern Utah ◽

Winter Annual ◽

Feral Rye ◽

Individual Patch

Feral cereal rye is an aggressive, persistent winter annual grass. Although feral rye has been documented as a weed in Utah cropland for many years, it has only recently been described as a weed of natural areas in Utah. After feral rye was observed on hillside locations where it had not previously been present, research was conducted to evaluate expansion rates in isolated patches and on a landscape scale. Individual patch measurements indicated expansion rates of 17%, 42%, 44%, and 112% in 2009. The landscape expansion rates were 1%, 4%, 8%, 21%, and 50% in the same year. The spread of feral rye appears to have occurred primarily on south- to west-facing slopes where the density and diversity of native species is limited. The expansion of feral rye into natural, undisturbed areas indicates that this species should be closely monitored. The relatively short seed longevity and current small infestations make it a good candidate for early detection/rapid response efforts.

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Ecology of Germination and Flowering in the Weedy Winter Annual Grass Bromus japonicus

Journal of Range Management ◽

10.2307/3897906 ◽

1981 ◽

Vol 34 (5) ◽

pp. 369 ◽

Cited By ~ 25

Author(s):

J. M. Baskin ◽

C. C. Baskin

Keyword(s):

Annual Grass ◽

Ecology Of Germination ◽

Winter Annual

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Seed retention of winter annual grass weeds at winter wheat harvest maturity shows potential for harvest weed seed control

Weed Technology ◽

10.1017/wet.2019.108 ◽

2019 ◽

Vol 34 (2) ◽

pp. 266-271 ◽

Cited By ~ 5

Author(s):

Neeta Soni ◽

Scott J. Nissen ◽

Philip Westra ◽

Jason K. Norsworthy ◽

Michael J. Walsh ◽

...

Keyword(s):

Winter Wheat ◽

Great Plains ◽

Downy Brome ◽

Annual Grass ◽

Weed Seed ◽

Weed Species ◽

Jointed Goatgrass ◽

Seed Retention ◽

Winter Annual ◽

Feral Rye

AbstractDowny brome, feral rye, and jointed goatgrass are problematic winter annual grasses in central Great Plains winter wheat production. Integrated control strategies are needed to manage winter annual grasses and reduce selection pressure exerted on these weed populations by the limited herbicide options currently available. Harvest weed-seed control (HWSC) methods aim to remove or destroy weed seeds, thereby reducing seed-bank enrichment at crop harvest. An added advantage is the potential to reduce herbicide-resistant weed seeds that are more likely to be present at harvest, thereby providing a nonchemical resistance-management strategy. Our objective was to assess the potential for HWSC of winter annual grass weeds in winter wheat by measuring seed retention at harvest and destruction percentage in an impact mill. During 2015 and 2016, 40 wheat fields in eastern Colorado were sampled. Seed retention was quantified and compared per weed species by counting seed retained above the harvested fraction of the wheat upper canopy (15 cm and above), seed retained below 15 cm, and shattered seed on the soil surface at wheat harvest. A stand-mounted impact mill device was used to determine the percent seed destruction of grass weed species in processed wheat chaff. Averaged across both years, seed retention (±SE) was 75% ± 2.9%, 90% ± 1.7%, and 76% ± 4.3% for downy brome, feral rye, and jointed goatgrass, respectively. Seed retention was most variable for downy brome, because 59% of the samples had at least 75% seed retention, whereas the proportions for feral rye and jointed goatgrass samples with at least 75% seed retention were 93% and 70%, respectively. Weed seed destruction percentages were at least 98% for all three species. These results suggest HWSC could be implemented as an integrated strategy for winter annual grass management in central Great Plains winter wheat cropping systems.

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Imazamox for Winter Annual Grass Control in Imidazolinone-Tolerant Winter Wheat

Weed Technology ◽

10.1614/wt-03-115r1 ◽

2004 ◽

Vol 18 (4) ◽

pp. 924-930 ◽

Cited By ~ 20

Author(s):

Patrick W. Geier ◽

Phillip W. Stahlman ◽

Anthony D. White ◽

Stephen D. Miller ◽

Craig M. Alford ◽

...

Keyword(s):

Winter Wheat ◽

Field Experiments ◽

Wheat Yield ◽

Early Spring ◽

Annual Grass ◽

Application Timing ◽

Jointed Goatgrass ◽

Early Fall ◽

Winter Annual ◽

Feral Rye

Field experiments were conducted at five locations in Kansas, Nebraska, and Wyoming to determine the effects of imazamox rate and application timing on winter annual grass control and crop response in imidazolinone-tolerant winter wheat. Imazamox at 35, 44, or 53 g ai/ha applied early-fall postemergence (EFP), late-fall postemergence, early-spring postemergence (ESP), or late-spring postemergence (LSP) controlled jointed goatgrass at least 95% in all experiments. Feral rye control with imazamox was 95 to 99%, regardless of rate or application timing at Hays, KS, in 2001. Feral rye control at Sidney, NE, and Torrington, WY, was highest (78 to 85%) with imazamox at 44 or 53 g/ha. At Sidney and Torrington, feral rye control was greatest when imazamox was applied EFP. Imazamox stunted wheat <10% in two experiments at Torrington, but EFP or LSP herbicide treatments in the Sidney experiment and ESP or LSP treatments in two Hays experiments caused moderate (12 to 34%) wheat injury. Wheat injury increased as imazamox rate increased. Wheat receiving imazamox LSP yielded less grain than wheat treated at other application timings in each Hays experiment and at Sidney in 2001. No yield differences occurred in one Torrington experiment. However, yields generally decreased as imazamox application timing was delayed in the other Torrington experiment. Generally, imazamox applied in the fall provided the greatest weed control, caused the least wheat injury, and maximized wheat yield.

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Dose-Responses of Weeds and Winter Wheat (Triticum aestivum) to MON 37500

Weed Technology ◽

10.1017/s0890037x0004094x ◽

1996 ◽

Vol 10 (4) ◽

pp. 870-875 ◽

Cited By ~ 12

Author(s):

Patrick W. Geier ◽

Phillip W. Stahlman

Keyword(s):

Winter Wheat ◽

Residual Effects ◽

Downy Brome ◽

Annual Grass ◽

Jointed Goatgrass ◽

Weed Growth ◽

Annual Grasses ◽

Winter Annual ◽

Dose Responses ◽

Weed Emergence

Greenhouse studies determined the dose-responses of cheat, downy brome, Japanese brome, jointed goatgrass, and winter wheat to preplant-incorporated MON 37500 and its residual effects on kochia. Concentrations of MON 37500 up to 60 ppbw did not affect winter wheat. MON 37500 did not prevent weed emergence, but increasingly inhibited weed growth as the dose was increased up to about 20 ppbw. GR50values were 16, 16, 11, and 31 ppbw for cheat, downy brome, Japanese brome, and jointed goatgrass, respectively. Japanese brome was more susceptible than cheat or downy brome, and jointed goatgrass tolerated two to three times more MON 37500 than theBromusspecies. Plant dry weights of kochia seeded after removal of the winter annual grasses decreased with increasing initial MON 37500 concentrations up to 20 ppbw. Kochia density was influenced by which winter annual grass was grown previously.

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Effects of Imazapic on Target and Nontarget Vegetation during Revegetation

Weed Technology ◽

10.1614/wt-06-131.1 ◽

2007 ◽

Vol 21 (4) ◽

pp. 1071-1081 ◽

Cited By ~ 45

Author(s):

Roger L. Sheley ◽

Michael F. Carpinelli ◽

Kimberly J. Reever Morghan

Keyword(s):

Prescribed Fire ◽

Application Rate ◽

Annual Grass ◽

Herbicide Application ◽

Burn Treatment ◽

Application Rates ◽

Nontarget Species ◽

Annual Grasses ◽

Winter Annual ◽

Plot Design

Medusahead is an introduced, winter-annual grass covering millions of hectares of the semiarid West. It forms exclusive stands and has a dense thatch cover that resists the establishment of desirable species. Prescribed fire can remove medusahead litter and improve plant establishment. Medusahead control is fundamental to establishing desirable species that will, in turn, resist further invasion. Imazapic is an effective herbicide for control of medusahead, but more information is needed on its effects on desirable species. Our objectives were to test how imazapic application rate and timing affected medusahead, seeded desirable species, and other nontarget vegetation on burned and unburned rangeland in southeast Oregon. We burned existing medusahead infestations at two different sites in June 2003. Following the burn, imazapic was applied at rates of 0, 35, 70, 105, 140, 175, and 210 g ai/ha between July and October of 2003 in a randomized strip-plot design. In November 2003, monocultures of seven desirable species were drill-seeded across the imazapic treated areas. Data on cover and density of medusahead and seeded species were collected in 2004 and 2005. Cover data of nontarget species were collected in the summer of 2005. Medusahead cover was highest in control plots and lowest in plots that received the highest herbicide application rates. Medusahead cover was lower in burned plots. The effect of imazapic on nontarget vegetation was less clear. Seeded species established in the study plots, but their response to herbicide rate showed few consistent patterns; some of the seeded species showed little response to herbicide, whereas others appeared to establish best at different herbicide rates, depending on site and whether the plots were burned or unburned. Site and burn treatment also affected how imazapic rate or application month influenced cover of perennial or annual grasses or forbs.

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