Fall and Spring Preplant Herbicide Applications Influence Spring Emergence of Glyphosate-Resistant Horseweed (Conyza canadensis)

Vince M. Davis; Greg R. Kruger; Bryan G. Young; William G. Johnson

doi:10.1614/wt-09-064.1

Fall and Spring Preplant Herbicide Applications Influence Spring Emergence of Glyphosate-Resistant Horseweed (Conyza canadensis)

Weed Technology ◽

10.1614/wt-09-064.1 ◽

2010 ◽

Vol 24 (1) ◽

pp. 11-19 ◽

Cited By ~ 23

Author(s):

Vince M. Davis ◽

Greg R. Kruger ◽

Bryan G. Young ◽

William G. Johnson

Keyword(s):

Early Spring ◽

Late Spring ◽

Conyza Canadensis ◽

No Till ◽

Early Fall ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds ◽

Spring Emergence ◽

Residual Control

Horseweed (Conyza canadensis) is a common weed in no-till crop production systems. It is problematic because of the frequent occurrence of biotypes resistant to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides and its ability to complete its life cycle as a winter or summer annual weed. Tactics to control horseweed while controlling other winter annual weeds routinely fail; herbicide application timing and spring emergence patterns of horseweed may be responsible. The objectives of this experiment were to (1) determine the influence of fall and spring herbicides with and without soil residual horseweed activity on spring-emerging glyphosate-resistant (GR) horseweed density and (2) evaluate the efficacy and persistence of saflufenacil on GR horseweed. Field studies were conducted in southern Indiana and Illinois from fall 2006 to summer 2007 and repeated in 2007 to 2008. Six preplant herbicide treatments were applied at four application timings: early fall, late fall, early spring, and late spring. Horseweed plants were counted every 2 wk following the first spring application until the first week of July. Horseweed almost exclusively emerged in the spring at both locations. Spring horseweed emergence was higher when 2,4-D + glyphosate was fall-applied and controlled other winter annual weeds. With fall-applied 2,4-D + glyphosate, over 90% of the peak horseweed density was observed before April 25. In contrast, only 25% of the peak horseweed density was observed in the untreated check by April 25. Starting from the initiation of horseweed emergence in late March, chlorimuron + tribenuron applied early fall or early spring, and spring-applied saflufenacil at 100 g ai/ha provided greater than 90% horseweed control for 12 wk. Early spring–applied saflufenacil at 50 g ai/ha provided 8 wk of greater than 90% residual control, and early spring–applied simazine provided 6 wk of greater than 90% control. When applied in late spring, saflufenacil was the only herbicide treatment that reduced horseweed densities by greater than 90% compared to 2,4-D + glyphosate. We concluded from this research that fall applications of nonresidual herbicides can increase the rate and density of spring emerging horseweed. In addition, spring-applied saflufenacil provides no-till producers with a new preplant herbicide for foliar and residual control of glyphosate- and ALS-resistant horseweed.

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Strategies for Control of Horseweed (Conyza canadensis) and Other Winter Annual Weeds in No-Till Corn

Weed Technology ◽

10.1614/wt-08-094.1 ◽

2009 ◽

Vol 23 (3) ◽

pp. 379-383 ◽

Cited By ~ 4

Author(s):

Gregory R. Armel ◽

Robert J. Richardson ◽

Henry P. Wilson ◽

Thomas E. Hines

Keyword(s):

Field Studies ◽

Conyza Canadensis ◽

Weed Species ◽

Annual Bluegrass ◽

No Till ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds

Field studies were conducted to determine if mesotrione alone or in combinations with other corn herbicides would control horseweed and other winter annual weeds associated with no-till corn. Mesotrione alone controlled horseweed 52 to 80% by 3 wk after treatment (WAT); however, by 7 WAT control diminished to between 37 to 68%, depending on mesotrione rate. Mesotrione at 0.16 kg ai/ha plus atrazine at 0.28 kg ai/ha controlled 99% of horseweed and annual bluegrass and 88% of yellow woodsorrel. Combinations of mesotrione at 0.16 kg/ha plus acetochlor at 1.79 kg ai/ha plus 1.12 kg ai/ha glyphosate (trimethylsulfonium salt of glyphosate) or 0.7 kg ai/ha paraquat provided 93% or greater control of all three weed species. Glyphosate alone also controlled all weed species 97 to 99%, while paraquat alone provided 99% control of annual bluegrass, 72% control of horseweed, and 36% control of yellow woodsorrel. Mixtures of paraquat plus acetochlor improved control of horseweed (93%) and yellow woodsorrel (73%) over control with either herbicide applied alone.

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Preplant and Residual Herbicide Application Timings for Weed Control in No-Till Soybean

Weed Technology ◽

10.1017/wet.2018.105 ◽

2019 ◽

Vol 33 (1) ◽

pp. 166-172 ◽

Cited By ~ 1

Author(s):

Kurt M. Vollmer ◽

Mark J. VanGessel ◽

Quintin R. Johnson ◽

Barbara A. Scott

Keyword(s):

Weed Control ◽

Early Spring ◽

Herbicide Application ◽

Emergence Period ◽

No Till ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds ◽

Residual Herbicide ◽

Application Programs

AbstractTimely herbicide applications for no-till soybean can be challenging given the diverse communities of both winter and summer annual weeds that are often present. Research was conducted to compare various approaches for nonselective and preplant weed control for no-till soybean. Nonselective herbicide application timings of fall (with and without a residual herbicide) followed by early-spring (4 wk before planting), late-spring (1 to 2 wk before planting), or sequential-spring applications (4 wk before planting and at planting) were compared. Spring applications also included a residual herbicide. For consistent control of winter annual weeds, two herbicide applications were needed, either a fall application followed by a spring application or sequential-spring applications. When a fall herbicide application did not include a residual herbicide, greater winter annual weed control resulted from early- or sequential-spring treatments. However, application timings that effectively controlled winter annual weeds did not effectively control summer annual weeds that have a prolonged emergence period. Palmer amaranth and large crabgrass control at 4 wk after planting was better when the spring residual treatment (chlorimuron plus metribuzin) was applied 1 to 2 wk before planting or at planting, compared with 4 wk before planting. Results indicate that in order to optimize control, herbicide application programs in soybean should coincide with seasonal growth cycles of winter and summer annual weeds.

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Effects of Seedling Emergence Timing on the Population Dynamics of Horseweed (Conyza canadensisvar.canadensis)

Weed Science ◽

10.1614/ws-d-13-00150.1 ◽

2014 ◽

Vol 62 (3) ◽

pp. 451-456 ◽

Cited By ~ 10

Author(s):

E. Tozzi ◽

R. C. Van Acker

Keyword(s):

Seedling Emergence ◽

Early Spring ◽

Higher Plant ◽

Southern Ontario ◽

Plant Densities ◽

Early Fall ◽

Winter Annual ◽

Dependent Growth ◽

Annual Weeds ◽

Spring Emergence

Horseweed is a surface-germinating ruderal facultative winter annual. The ruderal nature is a key adaptive characteristic that implicates emergence timing as an important recruitment factor. Experiments were established at three sites in southern Ontario, Canada, from 2009 to 2012 to determine the possible effect of emergence timing of horseweed on plant number, fecundity, and flowering timing. Emerged seedlings were tagged in 0.25-m2plots in five 2-wk cohorts in the fall and spring of each experimental season. Each plot was followed though until the plants contained within each plot completed their life cycle. Generally, spring-emerging plants were found to flower earlier than fall-emerging plants, but with fall emergence there were higher plant densities in August each season compared with spring emergence. Overall, there was no difference in fecundity between spring- or fall-emerging cohorts, but when cohorts were parsed beyond just spring or fall emergence, we found that plants emerging in early fall and early spring were more fecund and flowered earlier than plants emerging in late fall and late spring. Disturbance (tilled versus not-tilled) significantly affected emergence levels but not emergence timing. The differences in performance among emergence cohorts are likely due to spatial or temporal density-dependent growth advantages. These results show that spring-emerging cohorts of horseweed, especially early spring–emerging cohorts, should not be discounted when considering the weediness of this species, and this may hold true for other facultative winter annual weeds as well.

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Post-harvest Management of Tobacco Thrips (Thysanoptera: Thripidae) Overwintering in Peanut Fields

Journal of Entomological Science ◽

10.18474/0749-8004-28.4.433 ◽

1993 ◽

Vol 28 (4) ◽

pp. 433-446 ◽

Cited By ~ 7

Author(s):

J. R. Chamberlin ◽

J. W. Todd ◽

A. K. Culbreath ◽

W. C. Johnson ◽

J. W. Demski

Keyword(s):

Early Spring ◽

Late Winter ◽

Harvest Management ◽

Post Harvest ◽

Peanut Crop ◽

Survival And Reproduction ◽

Tobacco Thrips ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds

A combination of fallow tillage and a March application of carbofuran were assessed as tactics for decreasing survival and reproduction of tobacco thrips overwintering in six harvested peanut fields. Large numbers of tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), developed in three fields on volunteer peanut, Arachis hypogaea L., and winter annual weeds. Adult tobacco thrips collected during the late winter were predominantly brachypterous, with percent brachyptery averaging 71–95% for females. Brachypterous adults tended to be more abundant in fields harvested in September than in those harvested in October. Disking during November and February greatly reduced the density of volunteer peanut and winter annual weeds but did not measurably decrease abundance of brachypterous tobacco thrips. Carbofuran application reduced abundance of brachypterous adults and thrips larvae on volunteer peanut by 85–100% during the early spring. Post-harvest tillage and carbofuran application did not measurably reduce incidence of tomato spotted wilt virus in the subsequent peanut crop. Implications for winter ecology and management of spotted wilt are discussed.

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Weeds and Alfalfa Hay Quality

Weed Science ◽

10.1017/s0043174500027326 ◽

1973 ◽

Vol 21 (5) ◽

pp. 400-401 ◽

Cited By ~ 20

Author(s):

H. P. Cords

Keyword(s):

Medicago Sativa ◽

Protein Content ◽

Direct Effect ◽

Dormant Period ◽

Alfalfa Hay ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds

Established stands of alfalfa (Medicago sativa L. ‘Lahontan’) at six field locations were treated with soil-active herbicides during the dormant period for the control of winter annual weeds. Weeds and alfalfa were hand separated at the first harvest. This forage, which varied widely in weed content, was analyzed for protein. The percentage of protein correlated negatively with weed content in all cases. Analyses of covariance revealed that the direct effect of the herbicides on protein content was either small or absent and that the primary cause of the negative correlations was weed content.

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Influence of Winter Annual Weed Removal Timings on Soybean Cyst Nematode Population Density and Plant Biomass

Weed Science ◽

10.1614/ws-09-072.1 ◽

2010 ◽

Vol 58 (4) ◽

pp. 381-386 ◽

Cited By ~ 2

Author(s):

Valerie A. Mock ◽

J. Earl Creech ◽

Virginia R. Ferris ◽

Steven G. Hallett ◽

William G. Johnson

Keyword(s):

Soybean Cyst Nematode ◽

Plant Biomass ◽

Cyst Nematode ◽

Population Increase ◽

Population Densities ◽

Soybean Production ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds ◽

Weed Removal

Soybean cyst nematode (SCN) is one of the most yield limiting pathogens in U.S. soybean production. Henbit and purple deadnettle are winter annual weeds shown to facilitate SCN reproduction after crop harvest in the eastern Corn Belt. These weeds, along with volunteer soybean that germinates in autumn after harvest, are common to postharvest soybean production fields and provide an opportunity for SCN reproduction and population increase outside of the typical soybean production season. The objective of this experiment was to determine if autumn removal of these weeds and volunteer soybean can influence the winter weed seedbank, plant biomass, and SCN population densities. Microplots were established with or without Lamium spp. and volunteer soybean, and four winter weed removal timings (none, October, December, and May). Dry weights of autumn Lamium spp. were reduced 50% in October when grown in competition with volunteer soybean. SCN juveniles were found in henbit roots at higher densities in October (42 per gram of root) than December (5 per gram of root) and were also found in the roots of volunteer soybean (14 per gram of root) in October. SCN egg population densities were 50% lower in August after the summer fallow period. The results of this experiment suggest that autumn removal of winter annual weeds and volunteer soybean did not reduce SCN populations.

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Integrating fall and spring herbicides with a cereal rye cover crop for horseweed (Conyza canadensis) management prior to soybean

Weed Technology ◽

10.1017/wet.2019.116 ◽

2019 ◽

Vol 34 (1) ◽

pp. 64-72 ◽

Cited By ~ 1

Author(s):

Austin D. Sherman ◽

Erin R. Haramoto ◽

J. D. Green

Keyword(s):

Cover Crops ◽

Weed Management ◽

Field Experiments ◽

Production Systems ◽

Conyza Canadensis ◽

Cereal Rye ◽

Potential Interactions ◽

Herbicide Programs ◽

Spring Emergence ◽

Residual Control

AbstractHorseweed is one of Kentucky’s most common and problematic weeds in no-till soybean production systems. Emergence in the fall and spring necessitates control at these times because horseweed is best managed when small. Control is typically achieved through herbicides or cover crops (CCs); integrating these practices can lead to more sustainable weed management. Two years of field experiments were conducted over 2016 to 2017 and 2017 to 2018 in Versailles, KY, to examine the use of fall herbicide (FH; namely, saflufenacil or none), spring herbicide (SH; namely, 2,4-D; dicamba; or none), and CC (namely, cereal rye or none) for horseweed management prior to soybean. Treatments were examined with a fully factorial design to assess potential interactions. The CC biomass in 2016 to 2017 was higher relative to 2017 to 2018 and both herbicide programs reduced winter weed biomass in that year. The CC reduced horseweed density while growing and after termination in 1 yr. The FH reduced horseweed density through mid-spring. The FH also killed winter weeds that may have suppressed horseweed emergence; higher horseweed density resulted by soybean planting unless the CC was present to suppress the additional spring emergence. If either FH or CC was used, SH typically did not result in additional horseweed control. The SH killed emerged plants but did not provide residual control of a late horseweed flush in 2017 to 2018. These results suggest CCs can help manage spring flushes of horseweed emergence when nonresidual herbicide products are used, though this effect was short-lived when less CC biomass was present.

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Interference of Annual Weeds in Seedling Alfalfa (Medicago sativa)

Weed Science ◽

10.1017/s0043174500075445 ◽

1988 ◽

Vol 36 (5) ◽

pp. 583-588 ◽

Cited By ~ 14

Author(s):

Albert J. Fischer ◽

Jean H. Dawson ◽

Arnold P. Appleby

Keyword(s):

Medicago Sativa ◽

Bromus Tectorum ◽

Early Spring ◽

Amaranthus Retroflexus ◽

Downy Brome ◽

Weed Interference ◽

Alfalfa Hay ◽

Winter Annual ◽

Annual Weeds

Barnyardgrass [Echinochloa crus-galli(L.) Beauv. #4ECHCG] and pigweeds (mixture ofAmaranthus retroflexusL. # AMARE andA. powelliiS. Wats. # AMAPO) seeded separately with alfalfa (Medicago sativaL.) in mid-August suppressed alfalfa severely before frost killed them in October and November. Some alfalfa was killed, and yield of alfalfa forage was reduced in each of three harvests the following year. These weeds did not harm alfalfa seeded in mid-September. Downy brome (Bromus tectorumL. # BROTE) and tumble mustard (Sisymbrium altissimumL. # SSYAL) suppressed alfalfa seeded in August and September. They reduced alfalfa stands and reduced yield of alfalfa forage in each of three harvests the following year. Alfalfa seeded August 27 and allowed to compete with a mixture of these species for various periods was injured most by weeds that emerged with the alfalfa and remained uncontrolled until forage harvest in May. These weeds did not reduce alfalfa yields if removed by 36 days after alfalfa emergence. Thereafter, yield decreased as the period of weed interference increased. Interference was most damaging in early spring, when growth of winter annual weeds was rapid and vigorous. Weeds seeded 65 or more days after alfalfa emergence did not reduce alfalfa yields but sometimes produced enough biomass to reduce the quality of the first-cutting alfalfa hay.

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