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Control Strategies for Common Dandelion (Taraxacum officinale) in No-TillageCropping SystemsAuthor(s): Aaron S. Franssen and James J. KellsSource: Weed Technology, 21(1):18-22. 2007.Published By: Weed Science Society of AmericaDOI: http://dx.doi.org/10.1614/WT-04-212.1URL: http://www.bioone.org/doi/full/10.1614/WT-04-212.1

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Control Strategies for Common Dandelion (Taraxacum officinale)in No-Tillage Cropping Systems

Aaron S. Franssen and James J. Kells*

Common dandelion has developed into a troublesome agronomic weed for no-tillage corn and soybean producers inMichigan and throughout the north central region of the United States. Field experiments were conducted on establishedpopulations of common dandelion in 2001 to 2002 and 2002 to 2003 to evaluate the effect of preplant and sequentialherbicide applications on established populations of common dandelion. Preplant treatments of glyphosate or 2,4-D esterwere applied early fall, late fall, early spring, and late spring. For both glyphosate and 2,4-D ester, the fall applications weremore effective than the spring applications. Glyphosate at 840 g ae/ha was more effective than 2,4-D ester at 1,120 g ae/haat each application timing. A single application of glyphosate or 2,4-D ester applied either in the fall or spring did notprovide season-long control of common dandelion. Sequential treatments of glyphosate following preplant applications ofeither glyphosate or 2,4-D ester provided season-long control of common dandelion.Nomenclature: Glyphosate; 2,4-D ester; common dandelion, Taraxacum officinale Weber TAROF; glyphosate-resistantsoybean, Glycine max (L.) Merr.Key words: No-tillage, application timing, preplant treatment, sequential treatment.

Common dandelion has developed into a troublesomeagronomic weed in Michigan and throughout the NorthCentral region of the U.S. Typically considered a problematicweed unique to forage production and turf grass, theoccurrence of common dandelion in no-tillage corn andsoybean production is becoming more common. The no-tillage cropping system environment is conducive to theestablishment of common dandelion (Triplett and Lytle1972).

Common dandelion is a simple perennial that possessesa large fragile taproot that is used for carbohydrate storage andto acquire needed resources. Tillage operations associated withconventional-tillage crop production are an effective methodfor controlling perennial weeds such common dandelionbecause tillage disrupts the establishment and development ofthe taproot (Triplett 1985). Adoption of no-tillage systems bycrop producers has occurred in response to environmental andeconomic incentives. Soil conservation and reduced inputcosts are the primary drivers for this adoption ( Jasa et al.1991). However, no-tillage cropping systems have a higherreliance on herbicides for weed control (Koskinen andMcWhorter 1986), often requiring multiple herbicideapplications to manage perennial species (Buhler andMercurio 1988; Buhler and Proost 1990).

Nonselective herbicides, such as glyphosate, are widely usedfor vegetation management prior to planting and post-emergence in no-tillage glyphosate-resistant cropping systems.A disadvantage of the use of glyphosate as a preplant andpostemergence treatment is the lack of residual soil activity(Sprankle et al. 1975a, 1975b). A consequence of the exclusiveuse of glyphosate without the addition of soil-applied residualherbicides is the potential for weeds, including commondandelion seedlings, to emerge following the glyphosate

application. Glyphosate is effective in controlling manytroublesome perennial weeds (Davison 1972). However,common dandelion is often the one weed not completelycontrolled. Furthermore, as common dandelion seedlingsbecome established, they become more difficult to control(Triplett et al. 1977). The objectives of this research were todetermine the effect of herbicide, application timing, andsequential applications on control of established populationsof common dandelion in no-tillage cropping systems.

Materials and Methods

Two separate field experiments were initiated to evaluatecontrol strategies for common dandelion using glyphosate1

and 2,4-D ester.2 In the first experiment, treatments ofglyphosate and/or 2,4-D ester were applied at four applicationtimings prior to crop planting. In the second experiment,sequential applications of glyphosate following either glypho-sate or 2,4-D ester were evaluated. Initial applications ofglyphosate or 2,4-D ester were applied preplant either in thefall or spring. Sequential applications of glyphosate wereapplied postemergence in glyphosate-resistant soybean.

Effect of Herbicide and Application Timing. Experimentsto evaluate preplant applications of glyphosate or 2,4-D esterwere conducted in 2001 to 2002 and 2002 to 2003 at theMichigan State University Clarksville Experiment Station.Two identical experiments were established on adjacent sitesin both 2001 to 2002 and 2002 to 2003. Experiments wereconducted on sites with established populations of commondandelion that had been in a no-tillage corn–soybean rotationfor 3 yr. The soil at the experimental site was a loam withpH 6.8 and 1.8% organic matter. Experimental sites wereprepared by removing the previous corn crop as silageapproximately 1 mo before the initial fall applications. Plotsmeasured 3 m wide by 9 m long. Herbicide treatments wereapplied with a tractor-mounted, compressed-air sprayer

DOI: 10.1614/WT-04-212.1* Former Graduate Research Assistant and Professor, Department of Crop and

Soil Sciences, Michigan State University, East Lansing, MI 48824. Correspond-ing author’s E-mail: kells@msu.edu

Weed Technology 2007 21:18–22

18 N Weed Technology 21, January–March 2007

equipped with TeeJet XR8003 flat-fan nozzle tips3 calibratedto deliver 187 L/ha at 207 kPa.

Treatments of glyphosate or 2,4-D ester were applied atfour application timings prior to crop planting; early fall(EFALL), late fall (LFALL), early spring (ESPRING), and latespring (LSPRING) (Table 1). Glyphosate and 2,4-D esterwere applied at typical use rates to evaluate commondandelion control. Glyphosate was applied at 420 g ae/haand 840 g ae/ha; 2,4-D ester was applied at 560 g ae/ha and1,120 g ae/ha. A tank mixture of glyphosate plus 2,4-D esterat 420 g/ha and 560 g/ha, respectively, was also applied ateach of the four preplant timings. All treatments containingglyphosate were applied with 2% (w/v) ammonium sulfate.Common dandelion control was evaluated visually at cropplanting and was recorded as percent control as compared tothe nontreated; where 0 5 no control and 100 5 completecommon dandelion death.

Effect of Sequential Applications. Field experiments wereconducted in glyphosate-resistant soybean to evaluate theeffectiveness of sequential applications of glyphosate followinginitial applications of either glyphosate or 2,4-D ester.Experiments were conducted in 2001 to 2002 and 2002 to2003 at the Michigan State University Clarksville ExperimentStation as described above. Glyphosate-resistant soybean4 wasplanted at a population of 494,000 seeds/ha in 19-cm rows,approximately 3 wk after the initial spring application. In2002 to 2003, s-metolachlor5 was applied preemergence overthe entire study at 1424 g ai/ha for annual weed control. Apostemergence application of quizalofop-P-ethyl6 at 49 g ai/ha was applied with nonionic surfactant7 at 0.25% (v/v) forgrass control in both 2001 to 2002 and 2002 to 2003.

Initial treatments of either glyphosate or 2,4-D ester at840 g/ha or 1,120 g/ha, respectively, were applied at twopreplant application timings—fall and spring. These applica-tion timings correspond with the LFALL and ESPRINGtimings described in Table 1. Sequential treatments ofglyphosate at 840 g/ha were applied postemergence toglyphosate-resistant soybean at the V3 or V6 crop stage.The sequential application at the V6 stage of soybean wasevaluated in 2002 to 2003 only. Common dandelion controlwas evaluated visually throughout the growing season.Soybeans were harvested and plant densities recorded onOctober 22, 2002 and October 23, 2003. Commondandelion plant density was recorded as the average numberof plants m22 counted from four randomly placed 0.3 3 0.3-m quadrats within each plot. All common dandelion plants,established and seedling, were counted in each quadrat.

Soybean yield was determined in 2001 to 2002 by hand-harvesting the middle 1.5 m of each 4.5-m-long plot. In 2002to 2003, the middle 1.5 m of each 9-m-long plot wasmechanically harvested with a research plot harvester.

The herbicide and application timing experiment wasconducted as a randomized complete block design. Treatmentswere replicated four times for each treatment and theexperiment was conducted four times. Data were subjected toanalysis of variance8 and means separated with the use of Fisher’sprotected LSD (a 5 0.05). Variances were determined to behomogeneous and the experiments were combined.

The sequential application experiment was established asa split block with four replications in 2001 to 2002; the wholeplot was the initial application and the subplot was thesequential application. In 2002 to 2003, the experiment wasconducted as a randomized complete block design with fourreplications. Data were subjected to analysis of variance andmeans separated with the use of Fisher’s protected LSD (a 50.05). Data collected in 2001 to 2002 and 2002 to 2003 arepresented separately. Similar trends were observed for commondandelion control when the initial treatment included eitherglyphosate or 2,4-D ester; therefore, only the data for the initialtreatment with glyphosate will be presented.

Results and Discussion

Effect of Herbicide and Application Timing. Significantdifferences in common dandelion control were observedbetween herbicides and herbicide rates. Glyphosate and 2,4-Dester at higher rates were more effective than at lower rates ateach of the four application timings (Figure 1). Glyphosateapplied at 840 g/ha was more effective than 2,4-D ester at1,120 g/ha, regardless of application timing. The mosteffective herbicide treatment to control common dandelionwas the LFALL application of glyphosate applied at 840 g/ha,resulting in 80% control (Figure 2). The effectiveness of fallapplications of glyphosate to control common dandelion hasbeen consistently demonstrated (Buhler and Mercurio 1988;Buhler and Proost 1990). At the same LFALL timing, 2,4-Dester at 1,120 g/ha provided 58% common dandelion con-trol. The most effective application timing for 2,4-D ester wasthe EFALL application timing, which resulted in 60% controlof common dandelion. Glyphosate applied at the same timingwas more effective with 74% control of common dandelion.Glyphosate at the lower rate was consistently more effectivethan 2,4-D ester at the lower rate at all application timings(Figure 1).

Table 1. Application timing, application date, and average air temperature for glyphosate and 2,4-D ester applications for common dandelion control.

Application timing

2001–2002 2002–2003

Date of application

Air temperaturea (C)

Date of application

Air temperaturea (C)

21 0 +1 21 0 +1

Early fall October 18, 2001 5 8 10 October 9, 2002 11 14 13Late fall November 5, 2001 8 5 8 November 9, 2002 13 12 13Early spring April 16, 2002 23 24 20 April 15, 2003 16 23 11Late spring April 30, 2002 6 8 9 April 29, 2003 17 12 12

a Average daily air temperature on the day before (21), the day of (0), and the day after (+1) herbicide application.

Franssen and Kells: Control strategies for common dandelion N 19

Timing of the preplant application was as critical as theherbicide and herbicide rate applied. For both glyphosate and2,4-D ester, the preplant applications in the fall were moreeffective than the spring applications (Figure 2), despite thefact that average daily temperatures at the time of applicationwere lower in the fall versus the spring, especially in 2001 to2002 (Table 1). Glyphosate applied at 840 g/ha provided 74and 80% control at the EFALL and LFALL timings,respectively. This same treatment at the ESPRING andLSPRING timings resulted in only 65 and 55% control,respectively. A similar trend of reduced control in the springwas also observed with 2,4-D ester (Figure 2). Reducedcontrol of common dandelion by spring treatments may relateto growth patterns of the plant in the spring. Carbohydratesstored in the taproot are mobilized to the abovegroundbiomass of the plant during rapid vegetative growth in thespring (Mann 1981; Rutherford and Deacon 1974). Applica-tions at this time may result in insufficient herbicidetranslocation to the roots for complete control. Furthermore,root tissue of common dandelion has the ability to generatenew shoots (Mann and Cavers 1979), resulting in reducedcontrol ratings later in the growing season.

Depending on application timing, a tank mixture ofglyphosate plus 2,4-D ester at reduced rates provided significantcommon dandelion control. However, glyphosate applied at840 g/ha was more effective than the tank-mixture at eachapplication timing (Figure 1). At the LFALL applicationtiming, the tank mixture was more effective than 420 g/ha ofglyphosate. Common dandelion control with the tank mixturewas more effective than 2,4-D ester at 1,120 g/ha at the LFALL,ESPRING, and LSPRING application timings. The tankmixture was as effective as 1,120 g/ha of 2,4-D ester at theEFALL application timing. The addition of 2,4-D ester toglyphosate did not antagonize common dandelion control whenapplied at the EFALL, LFALL, and LSPRING applicationtiming. However, at the ESPRING application timing, the tankmixture was less effective than 420 g/ha of glyphosate.

Effect of Sequential Applications. A single application ofglyphosate either in the fall or spring did not provide season-long control of common dandelion. However, the addition ofa sequential application of glyphosate was effective in providingseason-long control (Figure 3). Similarly, a single application of2,4-D ester did not provide season-long control, but a sequentialapplication of glyphosate following 2,4-D ester was effective(data not shown). In both 2001 to 2002 and 2002 to 2003,glyphosate applied in the fall followed by the sequentialapplication at the V3 stage of soybean provided greater than80% control. In 2002 to 2003, similar control was observedwith the fall application followed by the sequential applicationat the V6 stage of soybean with 87% control.

In 2001 to 2002, the spring application of glyphosatefollowed by the V3 stage of soybean provided 54% control.This was significantly lower than the same treatment in 2002to 2003 with 97% control. This discrepancy in controlbetween years could be attributed to the lack of significantrainfall in 2002 to 2003 following the spring applicationtiming. In 2002, the experimental site received over 160 mmof precipitation from January through April. This wasapproximately 100 mm more than in 2003. The dry weatherpattern reduced new seedling germination and plant regrowth.The lack of new plant growth in 2002 to 2003 is evident fromthe spring-only treatment of glyphosate that provided 75%control at harvest. This treatment provided only 20% controlin 2001 to 2002.

A single application of glyphosate applied in the fall orspring was not effective in reducing plant densities at harvest,as compared to the nontreated (Figure 3). However, theaddition of a sequential application of glyphosate was effectivein reducing common dandelion plant densities. In 2001 to2002 and 2002 to 2003 the addition of the sequentialapplication of glyphosate at the V3 stage of soybean reducedcommon dandelion plant densities as compared to the fall-only treatment of glyphosate. In 2002 to 2003, delaying thesequential application until the V6 stage of soybean alsosignificantly reduced common dandelion densities. A sequen-tial application of glyphosate following a spring treatment ofglyphosate did not reduce common dandelion densities ineither 2001 to 2002 or 2002 to 2003.

Timing of herbicide application had a significant effect onsoybean yield. In 2001 to 2002, the fall and spring applicationsof glyphosate did not result in soybean yield greater than the

Figure 2. Common dandelion control evaluated at planting with glyphosate and2,4-D ester as affected by application timing. Treatment means with the sameletter are not significantly different (a 5 0.05). EFALL 5 early fall; LFALL 5late fall; ESPRING 5 early spring; LSPRING 5 late spring.

Figure 1. Common dandelion control evaluated at planting with preplantapplications of glyphosate, 2,4-D ester, and a tank mixture of glyphosate plus 2,4-D ester at 420 g/ha and 560 g/ha, respectively, as affected by application timing.Treatment means within application timing with the same letter are notsignificantly different (a 5 0.05). EFALL 5 early fall; LFALL 5 late fall;ESPRING 5 early spring; LSPRING 5 late spring.

20 N Weed Technology 21, January–March 2007

untreated (Figure 3). In 2002 to 2003, the spring application ofglyphosate resulted in soybean yield greater than the nontreatedor the fall application. It is likely that the lack of moisture thatreduced weed seedling germination and regrowth in 2003contributed to this observation. Soybean yields resulting froma fall application of glyphosate followed by the sequentialapplication at the V3 stage of soybean were consistently amongthe highest in both 2001 to 2002 and 2002 to 2003. Delayingthe sequential application of glyphosate until the V6 stage ofsoybean following the spring application of glyphosate did notaffect soybean yield as compared with the sequential applicationat the V3 stage of soybean in 2002 to 2003. However, delaying

the sequential application following the initial fall application2,4-D ester did result in reduced soybean yield (data not shown).Reduction of soybean yield associated with the initial fallfollowed by the sequential application at the V6 stage of soybeanis likely due to early-season competition from annual weeds notcontrolled by the preemergence application of s-metolachlor.

It is apparent that established populations of commondandelion pose a significant challenge to no-tillage cropproducers. Common dandelion, when left uncontrolled, hasthe potential to negatively impact soybean production. Aneffective management strategy to control this weed includesfield monitoring and multiple herbicide applications. The lack

Figure 3. Common dandelion control, plant density, and soybean yield as affected by single and sequential herbicide applications. Treatment means within each graphwith the same letter are not significantly different (a 5 0.05). PP 5 preplant.

Franssen and Kells: Control strategies for common dandelion N 21

of residual control associated with glyphosate and 2,4-D estermakes sequential herbicide applications necessary to achieveseason-long control of common dandelion. An effectivestrategy to control common dandelion in no-tillage cropproduction should include fall applications of herbicides suchas glyphosate followed by a sequential postemergenceapplication of glyphosate in glyphosate-resistant crops. Thetiming of this postemergence application will depend onenvironmental conditions and the presence of emerged weeds.

Sources of Materials1 Roundup UltraMAXH, Monsanto Company, St. Louis, MO

63167.2 2,4-D ester, Tenkoz Inc., Alpharetta, GA 30202.3 Spraying Systems Co., P.O. Box 7900, Wheaton, IL 60189.4 DK 23-51, Dekalb Genetics Corp., Monsanto Company, St.

Louis, MO 63167.5 Dual II MagnumH, Syngenta Crop Protection, Inc., Greens-

boro, NC 27409.6 Assure IIH, E. I. du Pont de Nemours and Company,

Wilmington, DE 19898.7 Activator 90H, Loveland Industries, Inc., Greeley, CO 80632.8 Statistical Analysis System (SAS) software. Version 8.2. SAS

Institute, Inc., Box 8000, SAS Circle, Cary, NC 27513.

Acknowledgments

The authors wish to thank the Michigan Soybean PromotionCommittee, Corn Marketing Program of Michigan, andProject GREEEN for financial support of this project.

Literature Cited

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Triplett, G. B. and G. D. Lytle. 1972. Control and ecology of weeds incontinuous corn grown without tillage. Weed Sci. 20:453–457.

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Received July 9, 2004, and approved February 19, 2006.

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