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© 2004 Plant Management Network. Trumpetcreeper (Campsis radicans) can be Controlled by Herbicide Application in Soybean Jeffrey T. Edwards and Lawrence R. Oliver, University of Arkansas, Department of Crop, Soil, and Environmental Sciences, 1366 W Altheimer Drive, Fayetteville, AR 72704 Corresponding author: Jeffrey T. Edwards. jte01@uark.edu Edwards, J. T., and Oliver, L. R. 2004. Trumpetcreeper (Campsis radicans) can be controlled by herbicide application in soybean. Online. Crop Management doi:10.1094/CM-2004-0323-01-RS. Abstract A three-year field study was conducted at the Pine Tree Branch Research Station near Colt, AR to evaluate methods of long-term trumpetcreeper (Campsis radicans) control. Tillage type (no-tillage or disking to a 6-inch depth) and herbicide treatment were evaluated using a strip-plot design with four replications. Tillage alone provided greater than 70% early-season trumpetcreeper control the first year following cultivation, but control steadily diminished over the following two years. A fall application of glyphosate (Roundup Ultra 3 lb/gal) at 1.5 lb ae/acre or dicamba (Clarity 4 lb/gal) at 3 lb ae/acre produced greater than 80% trumpetcreeper control the following spring, but control was less than 70% by 2 years after application. An in-season application of glyphosate at 0.75 lb/acre provided greater than 85% control of trumpetcreeper regardless of tillage. A fall application of 2,4-D (2,4-D LV-4 3.8 lb/gal) at either 1 or 2 lb ae/acre did not provide more than 60% trumpetcreeper control. None of the herbicide treatments resulted in soybean injury or yield reduction. This research demonstrates that trumpetcreeper can be managed in soybean with dicamba or glyphosate applied the fall prior to crop establishment, or by an in-season application of glyphosate at rates and timings currently being used for broad-spectrum weed control. Introduction A member of the Bignoniacea family, trumpetcreeper (Campsis radicans) is a shrubby, woody, perennial vine commonly found in the midwestern and southeastern United States (11). The vine roots at the nodes as it grows along the top of the soil, is considered one of the ten most troublesome weeds in soybean in the Midsouth, and is the thirteenth most common weed in the Mississippi Delta (4,13). Yield benefits of perennial vine control are not well proven, but because vines such as trumpetcreeper can interfere with harvest operations, many producers continue to treat infested fields (5). Shallow tillage that incorporates trumpetcreeper seed to a depth greater than 2 inches is sufficient to prevent germination (1), and deep tillage has been shown to be an effective method of suppressing growth of perennial vines such as redvine (Brunnichia ovata Walt.) (8). However, no-till farming practices would eliminate tillage as an option for weed control in many soybean fields. Moreover, deep tillage operations are expensive to perform and can make spring planting operations difficult under wet conditions. Non-selective residual herbicides such as imazapyr have provided effective control of trumpetcreeper in forestry production, but such rates are too high to be used in row crop production (10). Furthermore, soybean is not tolerant to many of the herbicides used for perennial vine control, so herbicide control studies have emphasized either pre-season or post-harvest herbicide application timings (9,14). Shaw and Mack (14) determined that a spring application of dicamba at 1 lb/acre along with a repeat application in the fall was required to achieve adequate control of trumpetcreeper. However, in many soybean producing areas of the United States, there is difficulty obtaining sufficient fall growth after soybean harvest to allow uptake and translocation of herbicides before frost occurs (3). This complicates control because above-ground competition contributes to interference potential, indicating a need for in-season control. However, extensive carbohydrate movement to roots in the fall indicates that a fall herbicide application may be better suited for long-term control. There are several advantages to controlling perennial vines in the established crop, such as potential for lower herbicide use rates, more effective control of perennial vines (2), and control of other weed species with the same herbicide application. The advent of glyphosate-resistant soybean technology now offers a way of utilizing the broad-spectrum herbicide glyphosate to control perennial vines in-season. Price reductions in recent years have also made glyphosate more affordable as a perennial vine control method for soybean producers. Previous research has evaluated methods of suppressing trumpetcreeper growth prior to crop establishment, but more work is needed to evaluate long-term control strategies (3). The objective of this research was to evaluate the efficacy of a combination of in-season glyphosate applications, tillage, and fall herbicide applications as methods of trumpetcreeper control. Evaluating Chemical and Cultural Control of Trumpetcreeper A field experiment was conducted to evaluate both chemical and cultural methods of controlling trumpetcreeper in nonirrigated soybean over a three-year period. The experiment was conducted at the Pine Tree Branch Research Station near Colt, AR on a Calloway silt loam (fine-silty, mixed active, thermic Glossaquic Fragiudalf with 2% sand, 83% silt, 15% clay, 1% organic matter, and 5.6 pH). The plot location was naturally infested with trumpetcreeper at an average density of 2 stems per feet2. Experimental design was a strip-plot with four replications (blocks). The main effects were tillage type (fall tillage or no-tillage) and herbicide treatment (Table 1). Plot size was 10 by 15 feet, and plot randomization and location did not change during the experiment. Table 1. Control of trumpetcreeper at 0, 2, and 10 weeks after V4 in-season treatment (WAT) as affected by tillage and herbicide treatment at Colt, AR.a
a NT = no-till; T = tilled in fall of 1999 and 2000; 0 WAT ratings were taken at the V4 soybean growth stage. b Glyphosate applied as Roundup Ultra 3 lb ae/gal. c Fall herbicide treatments were only applied September 30, 1999. d Dicamba applied as Clarity 4 lb ae/gal + 1% V/V crop oil concentrate. e Dicamba was applied September 30, 1999 followed by glyphosate at the V4 soybean growth stage in 2000 and 2001. f All in-season glyphosate applications were made at the V4 soybean growth stage in 1999, 2000, and 2001. 1999 plot preparation and initial treatments. Previous researchers have stated difficulty in obtaining sufficient fall weed growth following soybean harvest, so all plots scheduled to receive a fall herbicide application were left fallow in 1999, thus allowing adequate trumpetcreeper growth prior to herbicide application. The entire plot area was sprayed with paraquat (Gramoxone 2.5 lb/gal) at 0.8 lb ae/acre prior to crop planting, and plots scheduled to receive in-season herbicide applications were drill-seeded June 10 with Hartz 4994 RR glyphosate-resistant soybean at the rate of 200,000 seeds per acre. Soybean emerged on June 18, 1999. All herbicide applications were made using a CO2 pressurized backpack sprayer at 3 mph delivering 10 gal/acre at 30 psi. In-crop herbicide treatments were applied June 29, 1999 at the V4 soybean growth stage (6). Visual estimations of percent trumpetcreeper shoot biomass reduction relative to untreated checks were taken 2 and 10 weeks after herbicide application. Soybean harvest occurred on October 21, 1999. In-season herbicide treatments were applied each year of the study, but fall treatments were only applied September 30, 1999, and were not repeated in 2000 or 2001. Tillage operations. In the fall of 1999 tillage treatments were performed 42 days after fall herbicide applications (November 11, 1999) by disking each plot scheduled to receive a tillage treatment to a 6-inch depth. Tillage operations were repeated the following year on November 18, 2000. No other tillage operations occurred during the study. 2000 - 2001 herbicide applications and measurements. Soybean was drill-seeded at a rate of 200,000 seeds per acre on May 18, 2000, and May 8, 2001, and soybean emerged on May 24, 2000, and May 15, 2001, respectively. In-season glyphosate (Roudup Ultra 3 lb/gallon) treatments were applied at the V4 soybean growth stage on June 14, 2000, and June 10, 2001. Visual estimations of percent trumpetcreeper shoot biomass reduction relative to untreated checks were taken at the time of herbicide application, as well as 2 and 10 weeks following application. Soybean was harvested September 18, 2000, and September 25, 2001, with a small plot combine. Data analysis. Yield and herbicide control ratings were subjected to analysis of variance using the PROC MIXED function of SAS version 8 (SAS Institute, Cary, NC). Preliminary analysis revealed significant year interactions, so statistical analyses were performed separately for each year. Tillage and herbicide treatment were treated as fixed effects and replication (block) and all of its interactions were treated as random effects. Means were separated using Fisher’s protected LSD. Standard errors for LSD calculations were obtained using individual contrast statements, and degrees of freedom for standard errors were obtained with the Satterthwaite approximation. Efficacy of Glyphosate & Dicamba for Trumpetcreeper Control Soybean yield was very low (7 to 14 bu/acre) each year and differences in yield among treatments were nonsignificant for each year (data not shown). Low yields were likely the result of late planting, shallow soil depth, and lack of irrigation. In 1999, all glyphosate applications at the V4 soybean growth stage provided greater than 75% control of trumpetcreeper. However, differences among treatments were nonsignificant (data not shown). Interactions among main effects were significant (P < 0.05) for weed control data at all rating dates in 2000 and 2001. Therefore, only data for interaction terms are presented. Tillage alone, conducted in the fall of 1999, resulted in 71% control of trumpetcreeper at the initial weed control rating in 2000, but control declined to 42% by late season (Table 1). Tillage operations in the fall of 1999 and 2000 resulted in less than 45% control of trumpetcreeper in 2001, indicating that tillage used alone does not provide adequate, long-term control. When glyphosate was the only herbicide applied, tillage had no effect on weed control in 2000 (Table 1). For example, fall-applied glyphosate at 0.75 lb/acre applied in conjunction with tillage resulted in 86% trumpetcreeper control at initial 2000 weed control ratings as compared to 83% trumpetcreeper control with fall-applied glyphosate alone. Rate of fall-applied glyphosate had no effect on early-season trumpetcreeper control in 2000 (the year following application). However, glyphosate at 1.5 lb/acre was necessary to achieve greater than 80% control throughout the 2000 growing season. Fall applications of glyphosate did not provide greater than 65% control in 2001 (2 years following application). Tillage enhanced the efficacy of dicamba (Clarity 4 lb ae/gallon) applied at 1 and 2 lb/acre in the fall of 1999. Thompson et al. (15) reported similar results in field trials evaluating the efficacy of dicamba at 0.56 and 0.72 lb/acre when applied to transplanted trumpetcreeper shoots. They reported that dicamba provided better control of shorter trumpetcreeper rootstock segments as a result of reduced vigor of trumpetcreeper plants due to tillage operations. However, our research indicates no difference in the efficacy of dicamba at 3 lb/acre with tillage compared to tillage used alone. Differential responses of herbicides to tillage operations are most likely the result of differing efficacy of these herbicides. Dicamba applied at 3 lb/acre resulted in greater than 80% trumpetcreeper control at a year following treatment compared to 60% control two years following treatment, regardless of tillage (Table 1). From an economic standpoint though, this treatment is more expensive and provides no better control than a glyphosate application at 1.5 lb/acre. Although no damage to soybean was observed in this study, high dicamba rates are a concern for potential carryover to a sensitive crop such as soybean (14). A tank mixture of dicamba at 1 lb/acre and glyphosate at 0.75 lb/acre had an antagonistic effect on glyphosate activity and offered no improvement over dicamba alone. This is not surprising, as Flint and Barrett (7) reported antagonism in similar tank mixtures when applied to field bindweed. Application of dicamba the fall prior to glyphosate application decreased full-season glyphosate efficacy in 2000 and 2001. The reduced control is most likely the result of decreased glyphosate uptake and translocation in plants that were damaged by dicamba applications the previous year. 2,4-D (2,4-D LV-4 3.8 lb/gal) at 1 or 2 lb ae/acre resulted in significantly lower weed control ratings at most of the rating periods when compared to the other herbicide treatments. At any of the rating periods across both years, there was less than 67% trumpetcreeper control (Table 1). Season-long weed control was achieved when glyphosate was applied at the V4 soybean growth stage. We found no benefit of glyphosate rates higher than 0.75 lb/acre, which agrees with previous reports by Yonce and Skroch (16). Furthermore, glyphosate at 0.75 lb/acre provided sufficient control of trumpetcreeper the spring following application, which allowed easier planting. Since in-season applications of glyphosate are now common practice in soybean production, this study indicates that trumpetcreeper control can be achieved at glyphosate rates already being used for control of other weeds. Therefore, glyphosate at 0.75 lb/acre applied at the V4 soybean growth stage will provide a means of long-term management of trumpetcreeper infestations with or without tillage. Crop competition can enhance weed control (12), but fall herbicide treatments evaluated in this study had no crop competition at the time of herbicide application, which makes comparisons of fall and spring treatments difficult. Our objective, however, was to evaluate control methods that were representative of common agricultural practices in the Midsouth soybean production area. With this in mind, we assumed that a producer might be willing to fallow an area infested with trumpetcreeper for one growing season to ensure adequate growth for herbicide treatment, provided the treatment gave long-term control. Operating under these assumptions, this study shows that if a soybean producer is planting a glyphosate-resistant cultivar, in-season applications of glyphosate at the rate of 0.75 lb/acre will be the best option for long-term control of trumpetcreeper in soybean. If cultivar selection does not allow in-season applications of glyphosate, a fall application of glyphosate at a rate of 1.5 lb/acre could provide adequate control of trumpetcreeper the following year. Literature Cited 1. Chachalis, D., and Reddy, K. N. 2000. Factors affecting Campsis radicans seed germination and seedling emergence. Weed Sci. 48:212-216. 2. Coble, H. D., and Slife, F. W. 1969. Development and control of honeyvine milkweed. Weed Sci. 17:352-356. 3. DeFelice, M. S., and Oliver, L. R. 1980. Redvine and trumpetcreeper control in soybean and grain sorghum. Ark. Farm Res. 29:5 4. Dowler, C. C. 1998. Weed survey - southern states broadleaf crops subsection. Proc. South. Weed Sci. Soc. 51:299-313. 5. Elmore, C. D., Heatherly, L. G., and Wesley, R. A. 1989. Perennial vine control in multiple cropping systems on a clay soil. Weed Technol. 3:282-287. 6. Fehr, W. R., and Caviness, C. E. 1977. Stage of soybean development. Iowa State Univ. Sci. Tech. Special Rep. 880. 7. Flint, J. L., and Barrett, M. 1989. Effects of glyphosate combination with 2,4-D or dicamba on field bindweed (Convolvulus arvensis). Weed Sci. 37:12-18. 8. Hurst, H. R. 1994. Redvine response to late-season herbicide tillage combinations on lay-out land. Miss. Agric. & For. Exp. Stn. Rpt. 19. 9. Mack, R. E., Hanson, C. L., and Shaw, D. R. 1986. Evaluation of preplant herbicide applications for redvine control in soybeans. Proc. South. Weed Sci. Soc. 39:77 10. Miller, J. H. 1998. Primary screening of forestry herbicides for control of Chinese privet (Ligustrum sinense), Chinese wisteria (Wisteria sinensis), and trumpetcreeper (Campsis radicans). Proc. South. Weed Sci. Soc. 51:161 11. Miller, J. H., and Miller, K. V. 1999. Forest plants of the southeast and their wildlife uses. South. Weed Sci. Soc., Champaign, IL. 12. Norsworthy, J. K., and Oliver, L. R. 2002. Hemp sesbania interference in drill-seeded glyphosate-resistant soybean. Weed Sci. 50:34-41. 13. Rankins, A., Jr., Byrd, J. D., Jr., Mask, D. B., and Barrett, J. W., Jr. 2001 Survey of weeds infesting Mississippi soybeans. Proc. South. Weed Sci. Soc. 54:155 14. Shaw, D. R., and Mack, R. E. 1991. Application timing of herbicides for the control of redvine (Brunnichia ovata). Weed Technol. 5:125-129. 15. Thompson, L., Jr., Slack, C. H., Augenstein, R. D., and Herron, J. W. 1973. Action and fate of 2,4-D and glyphosate behavior in trumpetcreeper. Weed Sci. 21:429-432. 16. Yonce, M. H., and Skroch, W. A. 1989. Control of selected perennial weeds with glyphosate. Weed Sci. 37:360-364. |
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