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© 2008 Plant Management Network.
Accepted for publication 18 March 2008. Published 25 June 2008.

Roughstalk Bluegrass and Tall Fescue Control in Kentucky Bluegrass with Sulfosulfuron

Patrick E. McCullough and Stephen E. Hart, Department of Plant Biology and Pathology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901-8520

Corresponding author: Patrick E. McCullough. mccullough@aesop.rutgers.edu

McCullough, P. E., and Hart, S. E. 2008. Roughstalk bluegrass and tall fescue control in Kentucky bluegrass with sulfosulfuron. Online. Applied Turfgrass Science doi:10.1094/ATS-2008-0625-01-RS.

Abstract

Roughstalk bluegrass (Poa trivialis L.) and tall fescue [Festuca arundinaceae (L.) Shreb.] are problematic weeds in Kentucky bluegrass (Poa pratensis L.) with limited herbicides for selective control. Field experiments in 2006 and 2007 investigated sulfosulfuron efficacy on these weeds in Kentucky bluegrass. Sulfosulfuron controlled tall fescue ≥ 97% and was similar to sequential chlorsulfuron applications. However, sulfosulfuron was not as injurious to Kentucky bluegrass as sequential chlorsulfuron treatments. Sulfosulfuron controlled roughstalk bluegrass up to 95% with acceptable turf injury (< 20%). Overall, sulfosulfuron appears to have potential for tall fescue and roughstalk bluegrass control in Kentucky bluegrass.

Introduction

Kentucky bluegrass is planted throughout the northeastern United States for its desirable color, quality, and cold tolerance for lawns, sports fields, golf courses, and commercial turf sites (3). Tall fescue and roughstalk bluegrass are problematic perennial weeds of Kentucky bluegrass that are often introduced from seed contamination or indigenous plant material in soil (3,14). Tall fescue is extensively planted for turf but weedy clumps grown in Kentucky bluegrass reduce aesthetics and surface uniformity. Similarly, roughstalk bluegrass patches reduce Kentucky bluegrass quality, especially in summer months, from its lighter green color and poor stress tolerances (14,18). Controlling these weeds is often difficult due to Kentucky bluegrass sensitivity to many herbicides (5,6,7,8,9).

Sulfosulfuron is a sulfonylurea herbicide previously used in wheat and non-crop areas for control of roughstalk bluegrass, tall fescue, sedges (Cyperus spp.), and other problematic weeds (1,4,12,17,20). Sulfosulfuron selectively controls grassy weeds in grass crops by inhibiting the acetolactate synthase (ALS, EC 2.2.1.6) enzyme in susceptible plants (1,4,12,13,17,20,21). Researchers have noted Kentucky bluegrass has acceptable tolerance levels to sulfosulfuron relative to other ALS-inhibitors, and thus, may be applicable for controlling tall fescue and roughstalk bluegrass in turf (9,12).

Sulfosulfuron activity on tall fescue and roughstalk bluegrass has promising implications for Kentucky bluegrass management but previous investigations are limited to use in wheat and non-crop areas. Sulfosulfuron efficacy in turf warrants further investigations for successful integration into weed management programs. The objective of these experiments was to investigate sulfosulfuron application regimens for roughstalk bluegrass and tall fescue control in Kentucky bluegrass.

Tall Fescue Experiments

Experiments were conducted at Horticultural Research Farm II, North Brunswick, NJ, in 2006 and 2007. Kentucky bluegrass was established in the 1970s on a Nixon sandy loam with a pH of 6.3 and 3% organic matter. Cultivars planted were unknown by current turf managers. Kentucky bluegrass was a low-maintenance rough, fertilized with N at 49 kg/ha (1 lb/1000 ft²) annually, and mowed weekly at 7.6-cm (3-inch) height with clippings returned. Initial tall fescue populations were 49% (± 4) and 34% (± 3) in 2006 and 2007, respectively. Tall fescue variety was unknown but was likely a pasture-type grass.

Experimental design was a randomized complete block with four replications of 1 × 3-m (3 × 10-ft) plots. Plots in 2007 were adjacent to plots used in 2006. Sulfosulfuron was applied twice at 39 or 53 g ai/ha (0.56 or 0.75 oz ai/acre). Three chlorsulfuron treatments were applied for a standard comparison to sulfosulfuron. Chlorsulfuron at 193 g ai/ha (2.7 oz ai/acre) was applied as a single or sequential treatment while chlorsulfuron at 371 g ai/ha (5.3 oz ai/acre) was applied as a single treatment. An untreated check was included in both experiments. Treatments were applied 17 May and 6 June 2006 and 8 May and 12 June 2007. Both herbicides had a non-ionic surfactant included at 0.25% vol/vol. Treatments were applied with a single nozzle CO₂-pressured sprayer calibrated to deliver a total 375 liters/ha (40 gal/acre). Treatments were applied by making two passes per plot in opposite directions since one pass delivered a half rate of 187.5 liters/ha (20 gal/acre). Nozzles used were 9504E and CO₂-pressure regulators were set for 207 kPa (30 PSI).

Kentucky bluegrass injury was visually rated on a percent scale where 0 equaled no injury and 100 equaled dead turf. Injury greater than 20% was considered unacceptable. Tall fescue control was visually rated approximately ten weeks after initial treatments on a percent scale where 0 equaled no control and 100 equaled complete control. Control ratings were made based on ground cover reductions relative to initial populations. Data were subjected to analysis of variance and means were separated using Fisher’s protected LSD test at a = 0.05. Results are presented separately by year due to inconsistency of sequential application timings.

Roughstalk Bluegrass Experiments

Field experiments were conducted at New Jersey National Golf Club in Basking Ridge, NJ, in 2006 and 2007. Plots in 2007 were adjacent to plots used in 2006. Kentucky bluegrass was established in fall 1995 on a sandy loam with a 6.7 pH and 3% organic matter. Kentucky bluegrass cultivars originally planted in roughs were unknown by current managers. Turf was fertilized with N at 48 kg/ha (1 lb/1000 ft²) annually and mowed twice weekly at 8-cm height with clippings returned. Initial roughstalk bluegrass cover was 34% (± 7) and 11% (± 7) in 2006 and 2007, respectively.

Sulfosulfuron was applied once or twice at 26 g ai/ha (0.37 oz ai/acre) with an untreated check. Standard treatments were not used since selective herbicides for roughstalk bluegrass control are unavailable for Kentucky bluegrass. Treatments were applied 1 June and 26 June 2006 and 28 May and 25 June 2006. Experimental design, treatment applications, and data collection were similar to methodology described in North Brunswick experiments. Year by treatment interactions were detected for turf injury and weed control, and thus, results are presented by year.

Efficacy of Sulfosulfuron for Roughstock Bluegrass and Tall Fescue in Kentucky Bluegrass

In North Brunswick, tall fescue cover in untreated plots was similar to initial populations by ten weeks after initial treatments (WAIT) in both years (not shown). In 2006, single chlorsulfuron applications at 193 and 371 g/ha (2.75 and 5.3 oz/acre) controlled tall fescue 45 and 73%, respectively, while sequential chlorsulfuron applications at 193 g/ha (2.75 oz/acre) controlled tall fescue 100% (Table 1). Sequential sulfosulfuron applications at 39 and 53 g/ha (0.55 and 0.75 oz/acre) controlled tall fescue 99 and 100%, respectively. In 2007, single chlorsulfuron applications at 193 and 371 g/ha (2.75 and 5.3 oz/acre) controlled tall fescue 67 and 82%, respectively, while sequential chlorsulfuron applications at 193 g/ha (2.75 oz/acre) controlled tall fescue 98% (Table 1). Sequential sulfosulfuron applications at 39 and 53 g/ha (0.55 and 0.75 oz/acre) controlled tall fescue 97 and 98%, respectively.

Table 1. Tall fescue control in Kentucky bluegrass following herbicide applications in field experiments, 2006-2007, North Brunswick, NJ.

 ^x Treatments were applied 17 May and 6 June 2006 and 8 May and 12 June 2007 with a non-ionic surfactant at 0.25% vol/vol. Herbicide applied were Riverdale Corsair 75WDG (chlorsulfuron) (Nufarm Americas Inc., Burr Ridge, IL); Certainty 75WDG (sulfosulfuron) (Monsanto Co., St. Louis, MO); and X-77, non-ionic surfactant (Loveland Industries Inc., Greeley, CO).

 ^y Tall fescue control was rated 4 August 2006 and 13 July 2007.

Single chlorsulfuron applications at 371 g/ha (5.3 oz/acre) caused greater Kentucky bluegrass injury than sulfosulfuron by three WAIT in both years (Table 2). Sequential chlorsulfuron applications at 193 g/ha (2.75 oz/acre) caused 23 and 18% turf injury six and nine WAIT in 2006, respectively. Kentucky bluegrass injury from sulfosulfuron at both rates did not exceed 11% and was similar to single chlorsulfuron applications at 193 g/ha (2.75 oz/acre) on all dates. Differences between sulfosulfuron rates were not detected for turf injury.

Table 2. Kentucky bluegrass injury following herbicide applications in field experiments, 2006-2007, North Brunswick, NJ.

 ^x WAIT = week after initial treatment.

 ^y Treatments were applied 17 May and 6 June 2006 and 8 May and 12 June 2007 with a non-ionic surfactant at 0.25% vol/vol. Herbicides applied were Riverdale Corsair 75WDG (chlorsulfuron) (Nufarm Americas Inc., Burr Ridge, IL); Certainty 75WDG (sulfosulfuron) (Monsanto Co., St. Louis, MO); and X-77, non-ionic surfactant (Loveland Industries Inc., Greeley, CO).

Sulfosulfuron efficacy on tall fescue was comparable to sequential chlorsulfuron applications but was not as injurious to Kentucky bluegrass. Previous investigations have noted similar sulfosulfuron activity on Kentucky bluegrass and tall fescue. Lycan and Hart (11) noted sulfosulfuron injured Kentucky bluegrass and tall fescue but tall fescue did not recover from injury after eight weeks. Reicher and Weisenberger (19) noted sulfosulfuron reduced tall fescue turf cover approximately 90% and caused minimal Kentucky bluegrass injury. In other field experiments, ‘Baron’ Kentucky bluegrass injury ranged approximately 10 to 17% one month after sulfosulfuron treatments but turf recovered after two months (9).

Chlorsufluron efficacy on tall fescue was comparable to previous investigations. Dernoeden (7) noted chlorsulfuron controlled tall fescue 90% but Kentucky bluegrass injury levels were inconsistent. Larocque and Christians (10) noted similar chlorsulfuron efficacy on tall fescue while sequential applications were most effective. Single and sequential chlorsulfuron applications were noted to significantly injure turf-type tall fescue (2,7) and were reported to injure Kentucky bluegrass up to 39% from untreated. Results suggest sulfosulfuron has similar efficacy to sequential chlorsulfuron applications on tall fescue but is less injurious to Kentucky bluegrass.

In Basking Ridge, single sulfosulfuron applications did not injure Kentucky bluegrass (Table 3). Sequential sulfosulfuron applications injured Kentucky bluegrass 13% by six WAIT in 2007 but injury was acceptable and did not persist to the 8 WAIT evaluation. Roughstalk bluegrass cover in untreated plots declined by 30 and 15% from initial populations by 8 WAIT in 2006 and 2007, respectively. Single and sequential sulfosulfuron applications controlled roughstalk bluegrass 70 and 84%, respectively, eight WAIT in 2006. In 2007, single and sequential sulfosulfuron applications controlled roughstalk bluegrass 73 and 95%, respectively, but differences were not detected between application regimens. Although differences were not detected, activity of the higher sulfosulfuron rate appeared marginally greater than the lower rate for roughstalk bluegrass control, which may be of practical significance to end-users. Similar roughstalk bluegrass control has been noted from sequential sulfosulfuron applications in creeping bentgrass fairways (16,20).

Table 3. Kentucky bluegrass injury and roughstalk bluegrass control from sulfosulfuron at 26 g ai/ha applied once or twice in field experiments, 2006-2007, Basking Ridge, NJ.

 ^x WAIT = week after initial treatments.

 ^y Treatments were applied 1 June and 26 June 2006 and 30 May and 25 June 2007 with a non-ionic surfactant at 0.25% vol/vol. Products applied were Certainty 75WDG (sulfosulfuron) (Monsanto Co., St. Louis, MO) and X-77, non-ionic surfactant (Loveland Industries Inc., Greeley, CO).

Roughstalk bluegrass control in Kentucky bluegrass has been traditionally difficult due to a lack of selective herbicides. Sulfosulfuron appears efficacious for selective roughstalk bluegrass control in Kentucky bluegrass but long-term results have been inconsistent in previous research. In a three year experiment, summer applications of sulfosulfuron effectively controlled roughstalk bluegrass in creeping bentgrass, similar to results in Kentucky bluegrass (16). However, roughstalk bluegrass regrowth was noted in creeping bentgrass by fall and spring of each year which was comparable to initial populations (16). Although sulfosulfuron visually suppressed roughstalk bluegrass ground cover, belowground tissues may not have been completely controlled. Further research must investigate sulfosulfuron rates, regimens, and application timings for effective long-term roughstalk bluegrass control.

Kentucky bluegrass was not significantly injured by sulfosulfuron but tolerance to ALS-inhibitor herbicides often varies by variety due to wide genetic diversity of the species. In field experiments, Shortell et al. (22) noted several Kentucky bluegrass varieties tolerated bispyribac-sodium while others were completely killed following sequential applications. In other experiments, Kentucky bluegrass tolerance to ALS-inhibitor herbicides, such foramsulfuron and rimsulfuron, varied by variety and location throughout the Northeastern US (15). Similarly, biotype differences within grassy weed species, especially roughstalk bluegrass, may influence herbicide tolerance levels and warrant further investigations.

Literature Cited

1. Anonymous. 2005. Certainty Turf Herbicide. Monsanto Co., St. Louis, MO.

2. Beam, J. B., Barker, W. L., and Askew, S. D. 2005. Italian ryegrass (Lolium multiflorum) in newly seeded tall fescue. Weed Technol. 19:416-421.

3. Beard, J. B. 1973. Cool season turfgrasses. Pages 54-131 in: Turfgrass: Science and Culture. Prentice-Hall, Englewood Cliffs, NJ.

4. Chaleff, R. S., and Mauvais, C. J. 1984. Acetolactate synthase is the site of action of two sulfonylurea herbicides in higher plants. Science 224:1443-1445.

5. Dernoeden, P. H. 1986. Selective tall fescue control in Kentucky bluegrass turf with diclofop. Agron. J. 78:660-663.

6. Dernoeden, P. H. 1987. Tolerance of perennial ryegrass and tall fescue seedlings to fenoxaprop. Agron. J. 79:1035-1037.

7. Dernoeden, P. H. 1990. Comparison of three herbicides for selective tall fescue control in Kentucky bluegrass turf. Agron. J. 82:278-282.

8. Dernoeden, P. H., and Turner, T. R. 1988. Annual bluegrass control and tolerance of Kentucky bluegrass and perennial ryegrass to ethofumesate. HortSci. 23:565–567.

9. Hart, S. E., and McCullough, P. E. 2007. Annual bluegrass control in Kentucky bluegrass with bispyribac-sodium, primisulfuron, and sulfosufluron. Weed Technol. 21:251-254.

10. Larocque, D. J., and Christians, N. E. 1985. Selective control of tall fescue in Kentucky bluegrass with chlorsulfuron. Agron. J. 77:86-89.

11. Lycan, D. W., and Hart, S. E. 2004. Relative tolerance of four cool-season turfgrass species to sulfosulfuron. Weed Technol. 18:977-981.

12. Lycan, D. W., Hart, S. E., and Murphy, J. A. 2005. Annual bluegrass (Poa annua) control in Kentucky bluegrass (Poa pratensis) with sulfosulfuron. Int. Turf. Soc. Res. J. 10:1222-1226.

13. Maloy, B. M., and Christians, N. E. 1986. Tolerance of tall fescue and Kentucky bluegrass to chlorsulfuron under field conditions. Weed Sci. 34:431-434.

14. McCarty, B., Murphy, T., Whitwell, T., and Yelverton, F. 2005. Turfgrass weeds. Pages 663-703 in: Best Golf Course Management Practices, 2nd ed. L. B. McCarty, ed. Prentice-Hall, Upper Saddle River, NJ.

15. McCullough, P. E., Hart, S. E., Askew, S., Dernoeden, P. H., Reicher, Z., and Weisenberger, D. 2006. Kentucky bluegrass control with postemergence herbicides. HortSci. 41:255-258.

16. McCullough, P. E., and Hart, S. E. 2007. Roughtsalk bluegrass control in creeping bentgrass with bispyribac-sodium and sulfosulfuorn. Proc. Northeast Weed Sci. Soc. 61:82

17. Olson, B. L. S., Khatib, K. A., Stahlman, P., and Isakson, P. J. 2000. Efficacy and metabolism of MON 37500 in Triticum aestivum and weedy grass species as affected by temperature and soil moisture. Weed Sci. 48:541-548.

18. Prostak, R. G. 1994. The response of roughstalk bluegrass (Poa trivialis L.) and Kentucky bluegrass (Poa pratensis L.) to several postemergence herbicides. Ph.D. diss. Rutgers, The State Univ. of New Jersey, New Brunswick, NJ.

19. Reicher, Z., and Weisenberger, D. 2006. Tall fescue control in Kentucky bluegrass with Certainty herbicide. Online. 2006 Ann. Rep., Turfgrass Sci. Prog., Dept. of Agron., Purdue Univ., West Lafayette IN.

20. Riego, D. C., Williamson, D. H., and Graham, J. C. 2005. Roughstalk bluegrass control in creeping bentgrass with MON 44951 75WDG in Midwest and northeast US Proc. Northeast Weed Sci. Soc. 58:88.

21. Shimizu, T., Nakayama, I. Nagayama, K., Miyazawa, T., and Nezu, Y. 2002. Acetolactate Synthase Inhibitors. Pages 1-41 in: Herbicide Classes in Development: Mode of Action, Targets, Genetic Engineering, Chemistry. P. Böger, P. K. Wakabayashi, and K. Hirai. eds. Springer-Verlag, New York, NY.

22. Shortell, R. R., Hart, S. E., and Bonos, S. A. 2006. Evaluation of Kentucky bluegrass germplasm for bispyribac-sodium tolerance. Proc. Northeast Weed Sci. Soc. 60:88.