Common bermudagrass is a problematic weed within tall fescue turfgrass. Field research was conducted from 2010 to 2012 in Knoxville, TN, evaluating the efficacy of sequential applications of topramezone (12.5 and 25 g ha−1), triclopyr (1,120 g ha−1), and mixtures of topramezone + triclopyr for bermudagrass control in tall fescue turf. Sequential applications of fenoxaprop + triclopyr (100 + 1,120 g ha−1) were included for comparison. Three applications of each treatment were applied at 21-d intervals during July, August, and September of 2010 and 2011. Plots were stripped to receive tall fescue interseeding at 0 or 490 kg ha−1 during September 2010 and 2011. Bermudagrass control with topramezone + triclopyr mixtures was greater than topramezone or triclopyr applied alone 14 wk after initial treatment (WAIT) each year. In the second year of this study, topramezone + triclopyr mixtures controlled bermudagrass 27 to 50% compared to 27% for fenoxaprop + triclopyr by 52 WAIT. However, bermudagrass con...

https://bioone.org/journals/weed-technology/volume-27/issue-1/WT-D-12-00119.1/Bermudagrass-Cynodon-dactylon-Control-with-Topramezone-and-Triclopyr/10.1614/WT-D-12-00119.1.pdf

Bermudagrass (Cynodon dactylon) Control with Topramezone and Triclopyr

White bean is a high-value, important export field crop for farmers in Canada. Effective weed management in white bean is important as this crop is not competitive with weeds. Use of preplant incorporated, preemergence, and postemergence herbicides are effective means for weed control in white bean production in Canada. There are a range of herbicides registered for use on white bean in Canada, but in comparison with other high-acreage field crops such as corn and soybean, the options are relatively limited. This can pose challenges for white bean producers trying to use multiple herbicide modes of action to reduce the evolution of herbicide-resistant weeds and limits management options for troublesome weeds. In particular, management of perennial weeds in white bean with currently registered herbicides is difficult. There is a continued need to evaluate and register additional herbicide options for weed management in white bean in Canada.

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Managing weeds with herbicides in white bean in Canada: a review

Use of PRE herbicides for control of annual grassy weeds during commercial sod production has been limited. Research was conducted from 2010 to 2013 evaluating the effects of pendimethalin (3.36 kg ai ha−1), dithiopyr (0.56 kg ai ha−1), prodiamine (0.6 kg ai ha−1), oxadiazon (3.36 kg ai ha−1), prodiamine + sulfentrazone (0.84 + 0.41 kg ai ha−1), dimethenamid-P (1.68 kg ai ha−1), and indaziflam (0.03 and 0.05 kg ai ha−1) applications at sprigging on the establishment rate and tensile strength of ‘Tifway' hybrid bermudagrass sod at harvest (377 d after sprigging). All herbicides increased the days required to reach 50% hybrid bermudagrass cover compared with the nontreated control. Days required to reach 50% hybrid bermudagrass cover were lowest for oxadiazon and prodiamine (39 to 44 d), greatest for both rates of indaziflam (65 to 141 d), with dimethenamid-P, prodiamine plus sulfentrazone, pendimethalin, and dithiopyr ranking intermediate (45 to 63 d). Both rates of indaziflam reduced sod tensile ...

https://bioone.org/journals/Weed-Technology/volume-28/issue-1/WT-D-13-00102.1/Effects-of-Preemergence-Herbicides-on-the-Establishment-Rate-and-Tensile/10.1614/WT-D-13-00102.1.pdf

Effects of Preemergence Herbicides on the Establishment Rate and Tensile Strength of Hybrid Bermudagrass Sod

Tall fescue (Festuca arundinacea) and hybrid bluegrass (Poa pratensis L. 3 Poa arachnifera) can both be successfully grown in the transition zone of the United States. However, each grass has limitations. Tall fescue is susceptible to the fungal pathogen Rhizoctonia solani, whereas slow establishment and susceptibility to weed infestations limit hybrid bluegrass. Previous studies have shown the benefits of combining kentucky bluegrass with tall fescue in seeding mixtures. Research was conducted to evaluate the impact of two seeding combinations of hybrid bluegrass and tall fescue (one combination seeded at a 1.9:1 seed count ratio favoring tall fescue, the other combination seeded at a 1:1.8 seed count ratio favoring hybrid bluegrass) as well as monocultures of the species on turfgrass cover, weed species infestation, brown patch disease severity caused by R. solani, sod strength and species ecology. The seeding combinations had lower weed density during establishment and greater turf cover than the monoculture of hybrid bluegrass. The monoculture of tall fescue was subjected to more brown patch disease than the seeding combinations during and after the first year of establishment. Brown patch infestations likely reduced tall fescue cover and led to a species shift favoring hybrid bluegrass in the seeding combinations based on tiller count and weight data. Seeding combinations of tall fescue and hybrid bluegrass are beneficial from an epidemiological perspective because they reduce disease and weed infestations compared with monocultures of either species. From an agronomic perspective, the seeding combination favoring tall fescue provided the densest turf, whereas the seeding combination favoring hybrid had the greatest sod strength. Chemical name used: clopyralid (3,6 dichloropyridine-2 carboxylic acid) Turfgrasses make up a majority of commercial and residential landscapes in the United States. Sixteen million hectares of turfgrass is irrigated each year, which makes it the most irrigated crop when all species are taken into consideration (The Lawn Institute, 2010). Additionally, an estimated $2.8 billion U.S. of gasoline, $700 million U.S. of pesticides, and $5.2 billion U.S. of fossil fuel-derived fertilizers are used to manage lawns (The Lawn Institute, 2010). Turfgrasses provide erosion control, quicken restoration of disturbed soils, sequester CO2, dissipate urban heat, and reduce noise and visual pollution (Beard and Green, 1994). Individual homeowners manage many small areas of turfgrass. Therefore, adaptations of proper cultural practices are important to optimize the environmental, economic, use, and aesthetic impact of turfgrasses in home lawns. The most important cultural practice might be turfgrass selection, particularly when the home lawn is managed in the transition zone of the United States, which stretches from central New Jersey to the panhandle of Texas. Two cool-season turfgrasses that have desirable agronomic qualities and can be grown in the transition zone are tall fescue and hybrid bluegrass. Tall fescue [Festuca arundinacea Shreb synonym Schedonorus phoenix (Scop.) Holub] is the dominant cool-season perennial grass in the United States (Ju et al., 2006). Tall fescue provides great use as a lower maintenance turfgrass in the transition zone compared with other cool-season grasses. The plant’s well-developed root system, modest nitrogen requirements, and aesthetically pleasing dark green color make it a popular choice for home lawns, parks, golf course roughs, and other low-traffic situations. However, the major limiting factor to tall fescue’s success as a turf in the transition zone is its susceptibility to the fungal pathogen R. solani Kuhn (Piper and Coe, 1919), which causes the disease brown patch in the summer months. Brown patch is particularly problematic when nighttime temperatures average 21 C, relative humidity exceeds 85%, and the leaf wetness duration period is prolonged (Couch, 1995; Fidanza et al., 1996; Gross et al., 1998). No tall fescue cultivars are immune to R. solani; thus, applications of fungicides are necessary to effectively reduce brown patch spread (Yuen et al., 1994). Brown patch infestations not only decrease the aesthetic appearance of tall fescue, but can thin the turf stand, which may lead to infestation of undesirable weed species (Ferrell et al., 2003). Tall fescue’s bunchedtype growth habit limits recovery from brown patch infection (Turgeon, 1999). Hybrid bluegrass may be an alternative cool-season grass to grow in the transition zone. Hybrid bluegrass (Poa pratensis L. 3 Poa arachnifera Torr.) was created by crossing kentucky bluegrass (Poa pratensis L.) and texas bluegrass (Poa arachnifera Torr.) (Read et al., 1999). This cross results in a grass that has the agronomic qualities of kentucky bluegrass but the heat and drought characteristics of texas bluegrass. Hybrid bluegrass has a rhizomatous growth habit; thus, it exhibits better recuperative ability than a bunch-type grass like tall fescue and can fill in bare spots in a turfgrass stand. Hybrid bluegrass exhibits superior range in adaption compared with traditional cool-season grass cultivars; it can be grown in lawns as far south as Atlanta and Dallas. The rhizome system allows for turf recovery with less need for reseeding compared with tall fescue (Turgeon, 1999). Hybrid bluegrass’ shade tolerance compares with tall fescue and it is resistant to brown patch. In one study, ‘Thermal Blue Blaze’ hybrid bluegrass exhibited greater visual quality than traditional kentucky bluegrass and tall fescue in conditions of high temperature, drought, and salinity stress (Suplick-Ploense et al., 2002). Gross photosynthesis was reduced 21% in ‘Thermal Blue’ hybrid bluegrass, 30% in kentucky bluegrass, and 27% in tall fescue when plants were subjected to high temperature and drought conditions (Su et al., 2007). Electrolyte leakage was significantly less in hybrid bluegrass than kentucky bluegrass or tall fescue. Hybrid bluegrass use is limited by Received for publication 4 Dec. 2012. Accepted for publication 25 Feb. 2013. We thank Dr. Mike Goatley, Department of Crop and Soil Science, Virginia Tech, for providing the sod stretcher. Former Graduate Research Assistant. Current address: Postdoctoral Researcher, Plant Science Department, 252 Ellington Plant Science Building, 2431 Joe Johnson Drive, Knoxville, TN 37996. Professor. Research Associate. Assistant Professor. Research Assistant. To whom reprint requests should be addressed; e-mail mcutulle@utk.edu. HORTSCIENCE VOL. 48(4) APRIL 2013 493 TURF MANAGEMENT

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Impact of Hybrid Bluegrass and Tall Fescue Seeding Combinations on Brown Patch Severity and Weed Encroachment

White bean tolerance and weed control were examined by applying halosulfuron alone or in combination with pendimethalin, dimethenamid-P, or S-metolachlor applied PRE. All herbicides applied alone or in combination caused less than 3% visible injury 1 and 4 wk after emergence (WAE). Halosulfuron applied PRE provided greater than 95% control of common lambsquarters, wild mustard, redroot pigweed, and common ragweed and less than 55% control of green foxtail at 4 and 8 WAE. Weed density and dry weight at 8 WAE paralleled the control ratings. Dry bean yields in halosulfuron plus a soil applied grass herbicide did not differ compared to the weed-free control. Green foxtail competition with halosulfuron PRE applied alone resulted in reduced white bean yield compared to the weed-free control. Nomenclature: Dimethenamid-P; halosulfuron; pendimethalin; S-metolachlor; common lambsquarters, Chenopodium album L.; common ragweed, Ambrosia artemisiifolia L.; green foxtail, Setaria viridis (L.) Beauv.; redroot pigweed, ...

https://bioone.org/journals/weed-technology/volume-30/issue-1/WT-D-15-00084.1/Halosulfuron-Tank-Mixes-Applied-PRE-in-White-Bean/10.1614/WT-D-15-00084.1.pdf

Halosulfuron Tank-Mixes Applied PRE in White Bean

Field studies evaluated the effect of brown patch control on preemergence herbicide efficacy in tall fescue. Pendimethalin (1.7 followed by [fb] 1.7; 3.4 kg ai/ha), prodiamine (0.7 fb 0.6; 1.3 kg ai/ha), and oxadiazon (2.2 fb 2.2; 4.5 kg/ha), applied sequentially and as a single application, were evaluated for smooth crabgrass control with and without the use of azoxystrobin, a fungicide that controls brown patch. Azoxystrobin suppressed brown patch and increased smooth crabgrass control with pendimethalin in both years. This enhanced efficacy with azoxystrobin was attributed to improved tall fescue turf density and thus increased competition between this turf species and smooth crabgrass. Longer soil-residual herbicides such as oxadiazon and prodiamine provided high levels of smooth crabgrass control (often >90%). With the exception of oxadiazon at 4.5 kg ai/ha in 2000, smooth crabgrass control with oxadiazon and prodiamine was unaffected by the use of azoxystrobin. Nomenclature: Azoxystrobin, methyl (E)...

Leon L. Burpee

Papers

Effect of Brown Patch (Caused by Rhizoctonia solani) Control on Preemergence Herbicide Efficacy in Tall Fescue (Festuca arundinacea)1