Response of Biennial and Perennial Weeds to Selected ... - BioOne

Weed Technology. 2004. Volume 18:795–800

Response of Biennial and Perennial Weeds to Selected Herbicides and Prepackaged Herbicide Combinations in Grass Pastures and Hay Fields1 KEVIN W. BRADLEY, EDWARD S. HAGOOD, JR., KENNER P. LOVE, and RICK D. HEIDEL2 Abstract: Field trials were established in orchardgrass and tall fescue grass pastures and hay fields during 2000 and 2001 to evaluate wild carrot, broadleaf plantain, buckhorn plantain, bladder campion, and yellow crownbeard response to a variety of herbicides and prepackaged herbicide combinations. Picloram plus 2,4-D at 0.23 plus 0.84 kg/ha and higher, triclopyr plus clopyralid at 0.96 plus 0.32 kg/ha and higher, and 2,4-D plus triclopyr at 2.20 plus 1.12 kg/ha provided greater than 84% wild carrot, broadleaf plantain, and buckhorn plantain control at 4 mo after treatment (MAT) in both years. Metsulfuron, picloram plus 2,4-D at 0.30 plus 1.12 kg/ha, and 2,4-D plus triclopyr at 2.20 plus 1.12 kg/ha provided from 56 to 61% control of bladder campion 4 MAT, which was the highest bladder campion control observed in these trials. Greater than 80% yellow crownbeard control was achieved during both years with picloram plus 2,4-D at 0.15 plus 0.56 kg/ha and higher and with triclopyr plus clopyralid at 0.96 plus 0.32 kg/ha and higher. Results from these experiments reveal that good broad-spectrum control of many biennial and perennial broadleaf weeds can be achieved with higher rates of the picloram plus 2,4-D and triclopyr plus clopyralid prepackaged combinations. Nomenclature: Clopyralid; 2,4-D dimethylamine salt; metsulfuron; picloram; triclopyr; bladder campion, Silene vulgaris (Moench) Garcke #3 SILVU; broadleaf plantain, Plantago major L. # PLAMA; buckhorn plantain, Plantago lanceolata L. # PLALA; wild carrot, Daucus carota, L. # DAUCA; yellow crownbeard, Verbesina occidentalis (L.) Walter # VEEOC; orchardgrass, Dactylis glomerata L. ‘Benchmark’; tall fescue, Festuca arundinacea Schreb ‘Kentucky 31’. Additional index words: Pasture weed control, perennial weed control. Abbreviations: MAT, months after treatment.

INTRODUCTION

the normal lifespan of the desirable forage species (Bovey 1987; DiTomaso 2000; Malik and Waddington 1989). Bladder campion is an introduced perennial weed from Europe and Asia that primarily occurs as a weed of forages, pastures, and hay fields in Canada and the northern United States (Royer and Dickinson 1999). Bladder campion may reproduce both from fragmented root crowns and seed. Vrsek et al. (2000) found that this weed can produce as much as 1.4 grams of seed per plant and this seed has greater than 80% germinability. Bladder campion has become increasingly noticeable and troublesome in many pastures and hay fields in the northeastern United States during the past several years. Similarly, bladder campion has spread throughout many parts of Canada. Peschken and Derby (1990) reported that approximately 4,315 ha of cropland in Manitoba contained dense infestations of bladder campion and 81% of these fields were pastures, hay fields, or alfalfa seed fields. Krahulec et al. (2001) also found that bladder campion infestations increase under intensive grazing conditions. Few studies have been conducted on the control of bladder campion in pastures and hay fields with

Approximately 42% of the total land area in the United States is used for pastures and hay production, and weed infestations in these areas account for at least $2 billion in losses annually (DiTomaso 2000). Severe weed infestations in pastures and hay fields may cause reductions in livestock weight gain, meat or milk quality (or both), and may lower the quality and quantity of forage yields within infested areas (Cords 1973; Cosgrove and Barrett 1987; DiTomaso 2000; Pike and Stritzke 1984). Weeds can also compete with forages for moisture, nutrients, and light, and in some cases, weeds may decrease 1 Received for publication August 22, 2003, and in revised form January 13, 2004. 2 Former Postdoctoral Research Associate and Professor, Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0331; Extension Agent, Virginia Polytechnic Institute and State University, Rappahannock, VA 22747; Extension Agent, Virginia Polytechnic Institute and State University, Augusta, VA 24482. Corresponding author’s E-mail: [email protected]. 3 Letters following this symbol are a WSSA-approved computer code from Composite List of Weeds, Revised 1989. Available only on computer disk from WSSA, 810 East 10th Street, Lawrence, KS 66044-8897.

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herbicides. Todd and Goodwin (1984) observed good bladder campion control with chlorsulfuron, but this herbicide is not registered for use on pastures and hay fields in the eastern United States. Yellow crownbeard is another perennial weed that appears to be developing into more of a problem in pastures and hay fields throughout the Appalachian regions of Virginia and West Virginia (Belesky and Wright 1994). Yellow crownbeard is a member of the Asteraceae, which is the family that contains the largest number of weeds of pastures and hay fields in the United States (DiTomaso 2000). Yellow crownbeard may reach 2 to 3 m in height and may reproduce from seed and from a thick, overwintering basal crown. Because of this, yellow crownbeard is capable of rapidly colonizing a variety of environments including pastures, hay fields, roadsides, abandoned fields, and woodlands (Radford et al. 1968). Belesky and Wright (1994) observed a 12% increase in the prevalence of yellow crownbeard in continuously grazed pastures during a 3-yr time period. However, few studies have evaluated yellow crownbeard chemical control in these environments. Wild carrot, broadleaf plantain, and buckhorn plantain are all common species encountered in pastures and hay fields throughout Virginia and most of the eastern United States (Hawthorn and Cavers 1976; Mitich 1996; Uva et al. 1997). Wild carrot is usually a biennial but both annual and perennial forms of this plant can occur (Mitich 1996). Wild carrot has been cited as a troublesome weed along roadsides, on rights-of-way, and in lawns, pastures, hay fields, and no-tillage row crop production (Hall 1984; Stachler and Kells 1997). Although broadleaf and buckhorn plantain both occur as common weeds of turfgrass (Webster 2000), these species are rarely viewed as deleterious weeds of pastures and hay fields in the eastern United States. In fact, buckhorn plantain varieties have been developed commercially and investigated for use as perennial forages (Sanderson and Elwinger 2000a, 2000b; Stewart 1996). Similarly, Fairbairn and Thomas (1959) found broadleaf plantain to have high nutritive value when compared with 20 other weed species. Despite this, broadleaf and buckhorn plantain are often eliminated with herbicide applications that are usually intended for other broadleaf weed species. Although mechanical and biological control methods, grazing, and mowing are all common methods used to control weeds in pastures and hayfields, herbicide applications are the primary method of controlling weeds in these environments (Bussan and Dyer 1999). In the United States, growth regulator herbicides such as 2,4-D, clo796

pyralid, dicamba, picloram, and triclopyr are the most common herbicides used for selective broadleaf weed control in pastures and hay fields (DiTomaso 2000). However, in Virginia and several southeastern and midAtlantic States, picloram has not been registered for use on grass pastures until recently. In addition, several prepackaged growth regulator herbicide combinations have recently become available for use on grass pastures and hay fields in an effort to provide broad-spectrum broadleaf weed control. For these reasons, field trials were established during 2001 and 2002 to evaluate the response of wild carrot, broadleaf plantain, buckhorn plantain, bladder campion, and yellow crownbeard to a variety of herbicides and prepackaged herbicide combinations that are currently available for use on grass pastures and hay fields in several of the southeastern and MidAtlantic United States. MATERIALS AND METHODS

Field experiments were established in Rappahannock County, Virginia (388629N; 77889W), during 2001 and 2002 to evaluate the response of yellow crownbeard to a variety of herbicides and prepackaged herbicide combinations. Separate experiments were also established in Augusta County, Virginia (388369N; 79819W), during this time period to evaluate the response of bladder campion, broadleaf plantain, buckhorn plantain, and wild carrot to these same treatments. The soil at the 2001 Rappahannock County site was a Hiwassee clay loam (fine, kaolinitic, thermic Typic Rhodudults), whereas that at the 2002 Rappahannock County site was a Eubanks clay loam (fine-loamy, mixed, mesic Typic Hapludults). The Augusta County experiments contained a FrederickChristian silt loam (fine, mixed, semiactive, mesic Typic Paleudults) soil. At all locations, experiments were established on natural populations of weeds in existing pasture or hay fields that contained mixed populations of orchardgrass and tall fescue. All livestock were removed from the experimental areas. All herbicide treatments and rates are listed in Tables 2 and 3. The dimethylamine salt of 2,4-D4 was used during both years in the field trials conducted in Augusta County whereas the isooctyl ester of 2,4-D4 was applied in both trials conducted in Rappahannock County. The ester formulation of 2,4-D was used in the Rappahannock County trials because this salt is currently recommended for the control of yellow crownbeard in Virginia (E. S. Hagood, personal communication). In addition, the 4

Weedar, Nufarm Inc., Burr Ridge, IL 60527. Volume 18, Issue 3 (July–September) 2004

WEED TECHNOLOGY

Table 1. Weed density and height at application in the Augusta and Rappahannock County field trials during 2001 and 2002. Density at application Site and weed species

2001

2002

Height at application 2001

no./m

2002 cm

2

Augusta Buckhorn plantain Broadleaf plantain Wild carrot Bladder campion

7 4 4 2

10 11 1 2

10 11 11 20

9 6 9 10

Rappahannock Yellow crownbeard

17

19

25

27

triisopropanolamine salt of 2,4-D was applied in combination with picloram at all sites because this is the salt of 2,4-D used in this prepackaged formulation.5 Herbicide treatments were applied at 5 km/h with a hand-held CO2-pressurized backpack sprayer containing 8003 flat fan nozzle tips6 that delivered 210 L/ha. In Augusta County, individual plots were 3 by 12 m in 2001 and 3 by 9 m in 2002. In Rappahannock County, individual plots were 1.5 by 9 m in 2001 and 1.8 by 6 m in 2002. Treatments were arranged in a randomized complete block design with four replications in all experiments except for the 2001 Rappahannock County experiment that contained three replications. Herbicide treatments 5 6

Grazon P1D, DowAgroSciences LLC, Indianapolis, IN 46268. Spraying Systems Co.t, P.O. Box 7900, Wheaton, IL 60189.

were applied in the Augusta County experiments on June 14, 2001, and on June 27, 2002. In both years, the first cutting of hay had been harvested approximately 3 wk before herbicide applications. However, in the Rappahannock County experiments, herbicide treatments were applied early in the season on May 7 in 2001 and on May 15 in 2002, and no harvests had been conducted before the herbicide applications. No visible injury to orchardgrass or tall fescue was observed in either site in either year, perhaps because of the dense stand of weeds in these locations. Weed density and height at the time of herbicide applications are listed in Table 1. Visual weed control ratings were taken at monthly intervals throughout the growing season. These ratings were based on a scale of zero to 100, with zero equal to the vigor and ground cover observed in the untreated control plots and 100 equal to complete weed control. All data were analyzed using the generalized linear model procedure in SAS (1989) and means were separated with a LSD at the 5% level. There was a significant treatment by year interaction for all weeds except bladder campion. Therefore, bladder campion results are pooled over years, whereas other results are presented by year. All percent data were transformed using arcsine of the square root. Data transformation did not improve the model in either case; therefore, nontransformed data are presented.

Table 2. Response of buckhorn plantain, broadleaf plantain, wild carrot, and bladder campion to selected herbicides and prepackaged herbicide mixtures in Augusta County during 2001 and 2002 at 4 MAT.a Buckhorn plantain Treatment

b

Rate

Broadleaf plantain

2001

2002

2001

2002

90 93 95 38 96 93 100 100 99 48 91 95 98 93 95 10

79 75 59 13 60 40 64 84 96 51 65 88 88 63 94 15

90 88 94 37 96 93 100 98 99 46 85 91 96 94 95 11

81 76 68 15 70 44 74 89 97 60 63 87 91 66 96 15

kg ai/ha Metsulfuron Triclopyr 2,4-D Dicamba 2,4-D 1 dicamba Picloram 1 2,4-D Picloram 1 2,4-D Picloram 1 2,4-D Picloram 1 2,4-D Triclopyr 1 clopyralid Triclopyr 1 clopyralid Triclopyr 1 clopyralid Triclopyr 1 clopyralid 2,4-D 1 triclopyr 2,4-D 1 triclopyr LSD (0.05)

0.01 1.12 1.12 0.56 1.12 1 0.56 0.08 1 0.28 0.15 1 0.56 0.23 1 0.84 0.30 1 1.12 0.48 1 0.16 0.63 1 0.21 0.96 1 0.32 1.26 1 0.42 1.12 1 0.56 2.20 1 1.12 —

Wild carrot 2001

2002

Bladder campionc

70 80 59 30 61 73 100 100 99 70 80 100 100 70 95 13

90 80 71 23 84 28 78 89 88 75 81 88 86 71 93 14

61 34 16 13 27 19 34 43 56 25 31 38 43 41 61 11

%

Abbreviation: MAT, months after treatment. Metsulfuron and all triclopyr plus clopyralid prepackaged mixtures were applied with nonionic surfactant at 0.25% v/v. c Indicates pooled analysis of data from 2001 and 2002. a

b

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Table 3. Response of yellow crownbeard to selected herbicides and prepackaged herbicide mixtures in Rappahannock County during 2001 and 2002. Yellow crownbeard control 5 MATa Treatmentb

Rate

2001

kg ai/ha Metsulfuron 2,4-D 2,4-D Dicamba Dicamba 2,4-D 1 dicamba Picloram 1 2,4-D Picloram 1 2,4-D Picloram 1 2,4-D Picloram 1 2,4-D Triclopyr 1 clopyralid Triclopyr 1 clopyralid Triclopyr 1 clopyralid Triclopyr 1 clopyralid 2,4-D 1 triclopyr LSD (0.05)

0.01 1.12 2.24 0.56 1.12 1.12 1 0.56 0.08 1 0.28 0.15 1 0.56 0.23 1 0.84 0.30 1 1.12 0.48 1 0.16 0.63 1 0.21 0.96 1 0.32 1.26 1 0.42 1.12 1 0.56 —

2002 %

45 80 78 45 55 67 60 93 97 100 63 75 90 88 67 19

2 76 93 38 61 83 64 83 93 96 55 74 83 88 76 13

Abbreviation: MAT, months after treatment. Metsulfuron and all triclopyr plus clopyralid prepackaged mixtures were applied with nonionic surfactant at 0.25% v/v. a

b

RESULTS AND DISCUSSION

Augusta County Experiments. Visible control of all weed species was generally higher in the Augusta County experiment in 2001 than in 2002. This is likely because of plant stress at application as a result of the severe drought in Augusta County in 2002. For example, 9 cm of rainfall occurred during June at the Augusta county site in 2001 whereas only 1.8 cm of rainfall occurred during the same month in 2002. Picloram plus 2,4-D at 0.23 plus 0.84 kg ai/ha and higher, triclopyr plus clopyralid7 at 0.96 plus 0.32 kg ai/ ha and higher, and 2,4-D plus triclopyr8 at 2.20 plus 1.12 kg ai/ha provided similar and highest levels of buckhorn and broadleaf plantain control during both 2001 and 2002 (Table 2). However, in 2001, all the prepackaged herbicide rates evaluated except for triclopyr plus clopyralid at 0.48 plus 0.16 kg/ha controlled buckhorn and broadleaf plantain greater than 85%. Control of buckhorn and broadleaf plantain was also greater than 85% with 2,4-D plus dicamba, 2,4-D alone, triclopyr,9 and metsulfuron10 in 2001 but not in 2002. Dicamba11 at 0.56 kg ai/ha alone generally provided unacceptable control (,40%) of broadleaf and buckhorn plantain in either Redeem R&P, DowAgroSciences LLC, Indianapolis, IN 46268. Crossbow, DowAgroSciences LLC, Indianapolis, IN 46268. 9 Remedy, DowAgroSciences LLC, Indianapolis, IN 46268. 10 Ally, E. I. du Pont de Nemours and Company, Wilmington, DE 19898. 11 Banvel, MicroFlo Company LLC, Memphis TN 38117. 7 8

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year. Similar levels of broadleaf and buckhorn plantain control have also been observed in turfgrass with prepackaged mixes of triclopyr plus clopyralid and with 2,4-D (Neal 1990; Olson and Mackasey 1989; Sawyer and Jagschitz 1988). As with broadleaf and buckhorn plantain, picloram plus 2,4-D at 0.23 plus 0.84 kg/ha and higher, triclopyr plus clopyralid at 0.96 plus 0.32 kg/ha and higher, and 2,4-D plus triclopyr at 2.20 plus 1.12 kg/ha provided similar and highest levels of wild carrot control during both 2001 and 2002 (Table 2). Picloram plus 2,4-D at 0.15 plus 0.56 kg/ha also provided excellent wild carrot control in 2001 but not in 2002. Hall (1984) has also reported greater than 80% wild carrot control at 1 yr after treatment with applications of triclopyr and with applications of picloram plus 2,4-D. Metsulfuron, triclopyr, and 2,4-D plus dicamba provided some of the highest levels of wild carrot control in 2002 but lower levels of control in 2001. As with the plantains, dicamba alone at 0.56 kg/ha generally provided unacceptable control of wild carrot in either year. Metsulfuron, picloram plus 2,4-D at 0.30 plus 1.12 kg/ ha, and 2,4-D plus triclopyr at 2.20 plus 1.12 kg/ha provided from 56 to 61% control of bladder campion 4 mo after treatment (MAT), which was the highest bladder campion control observed in these trials (Table 2). Todd and Goodwin (1984) have also observed good bladder campion control with picloram at 0.5, 1.0, and 1.5 kg/ ha, but these rates are higher than those evaluated in this research and generally higher than those labeled for herbaceous weed control in pastures in the mid-Atlantic and southeastern United States (Anonymous 2003). All other treatments generally provided unacceptable control of bladder campion 4 MAT, which is consistent with reports by Peschken et al. (1997), who noted that this weed is tolerant to most herbicides commonly used on pastures and hay fields. Rappahannock County Experiments. Greater than 80% yellow crownbeard control was achieved at 5 MAT during both years with picloram plus 2,4-D at 0.15 plus 0.56 kg/ha and higher and with triclopyr plus clopyralid at 0.96 plus 0.32 kg/ha and higher (Table 3). These results suggest that higher rates of these prepackaged herbicide combinations can control troublesome perennial weeds such as yellow crownbeard in pastures and hay fields. Other researchers have also observed good control of the perennial weeds field bindweed (Convolvulus arvensis L.), honeyvine milkweed [Ampelamus albidus (Nutt.) Britt.], leafy spurge (Euphorbia esula L.), and tropical soda apple (Solanum viarum Dunal) with picloVolume 18, Issue 3 (July–September) 2004

WEED TECHNOLOGY

ram plus 2,4-D combinations (Call et al. 2000; Claassen and Moshier 1989; Lym and Messersmith 1985, 1994; Westra et al. 1992). Similarly, excellent control of the perennial weeds honey mesquite (Prosopis glandulosa Torr), Virginia buttonweed (Diodia virginiana L.), dandelion (Taraxacum officinale Weber), and Canada thistle (Cirsium arvense L.) has been observed with prepackaged combinations of triclopyr plus clopyralid (Bovey and Whisenant 1992; Gover et al. 1989; Olson and Mackasey 1989; Scott and Coats 1998). Applications of 2,4-D at 2.24 kg/ha and 2,4-D plus dicamba also provided greater than 80% yellow crownbeard control in 2002 but not in 2001. Lower rates of the picloram plus 2,4-D and triclopyr plus clopyralid prepackaged combinations, 2,4-D plus triclopyr, and dicamba at 1.12 kg/ha generally provided moderate (55 to 76%) levels of yellow crownbeard control 5 MAT, whereas metsulfuron and dicamba at 0.56 kg/ha provided the lowest levels of yellow crownbeard control in both years. Results from the Rappahannock and Augusta County experiments reveal that excellent control of many biennial and perennial broadleaf weeds can be achieved with higher rates of the prepackaged picloram plus 2,4-D mixture. For example, picloram plus 2,4-D at 0.30 plus 1.12 kg/ha provided higher buckhorn plantain, broadleaf plantain, wild carrot, bladder campion, and yellow crownbeard control than any other herbicide or herbicide combination evaluated in these experiments. Similar control of all weeds except bladder campion was also achieved with picloram plus 2,4-D at 0.23 plus 0.84 kg/ ha. Triclopyr plus clopyralid at 0.96 plus 0.32 kg/ha also provided greater than 80% control of all weeds except bladder campion when applied at 0.96 plus 0.32 kg/ha and higher. Collectively, these results indicate that the prepackaged combinations that provide the most effective broad-spectrum broadleaf weed control are: picloram plus 2,4-D . triclopyr plus clopyralid . 2,4-D plus triclopyr.

LITERATURE CITED Anonymous. 2003. Grazon P 1 D.t In Crop Protection Reference. 19th ed. New York: C & P. Pp. 764–770. Belesky, D. P. and R. J. Wright. 1994. Hill-pasture renovation using phosphate rock and stocking with sheep and goats. J. Prod. Agric. 7:233–238. Bovey, R. W. 1987. Weed control problems, approaches, and opportunities in rangeland. Rev. Weed Sci. 3:57–91. Bovey, R. W. and S. G. Whisenant. 1992. Honey mesquite (Prosopis glandulosa) control by synergistic action of clopyralid: triclopyr mixtures. Weed Sci. 40:563–567. Bussan, A. J. and W. E. Dyer. 1999. Herbicides and rangeland. In R. L. Sheley Volume 18, Issue 3 (July–September) 2004

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