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  • Author or Editor: B. J. Johnson x
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A ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] green-overseeded with ‘Medalist VI’ perennial ryegrass [Lolium perenne (L.)] was treated with variable rates and frequencies of 26% (flowable) tricalcium arsenate. Ryegrass was severely injured when tricalcium arsenate was applied in mid to late fall, after it had fully germinated. Injury to ryegrass was not as severe when applied prior to or during germination. Timing of chemical application had more effect on injury than rate of application.

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A field experiment was conducted over 2 years to determine the effects of treatment dates with plant growth regulators (PGRs) on performance of `Tifway' bermudagrass [Cynodon transvaalensis Burtt-Davy] × [C. dactylon (L.) Pers.]. For flurprimidol at 0.84 kg·ha-1, the highest injury occurred from 16 or 28 June application in 1987 and from 17 May or June application in 1988. The injury was similar from treatment dates with flurprimidol + mefluidide or paclobutrazol + mefluidide. The PGRs were applied over a longer period in 1987 than 1988 without affecting vegetative suppression of `Tifway' bermudagrass. However, in 1988, the suppression from the 17 May treatment was equal to or better than that obtained when treatment dates were delayed until 1 June or later. Chemical names: α-(1 -methylethyl)- α -[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol); N -[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide (mefluidide); (±)-(R*R*) β -[(4-chlorophenyl)-methyl]- α -(1,1-dimethylethyl)- 1H -1,2,4-triazole- 1-ethanol (paclobutrazol).

Free access
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Abstract

A field experiment was initiated to determine herbicidal activity on large crabgrasses (Digitaria sanguinalis (L.) Scop.] when core cultivation was performed in a common bermudagrass [Cynodon dactylon (L.) Pers.] turf after herbicide application. Core cultivation treatments were made prior to preemergence herbicide application or at 1, 2, 3, or 4 months after the chemicals were applied. Where oxadiazon (4.4 kg·ha−1), bensulide (11.2 kg·ha−1), bensulide + oxadiazon (6.7 + 1.7 kg·ha−1) and benefin (3.4 kg·ha−1) were applied, the timing of core cultivation had no significant influence on preemergence large crabgrass control. DCPA (14.0 kg·ha−1) was ineffective in controlling large crabgrass, regardless of core cultivation parameter. Chemical names used: 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2(3H)-one (oxadiazon); 0,0-bis(1-methylethyl)S-[2-[(phenylsulfonyl)amino] ethyl]phosphorodthioate (bensulide); N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine (benefin); dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate (DCPA).

Open Access
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Pendimethalin and oxadiazon are used commonly to control crabgrasses (Digitaria spp.) in tall fescue (Festuca arundinacea Schreb.) and common bermudagrass [Cynodon dactylon (L.) Pers.]. A field experiment was conducted for 2 years to determine if reduced pendimethalin and oxadiazon application rates would control large crabgrass [D. sanguinalis (L.) Sco.] effectively in tall fescue and common bermudagrass. Oxadiazon applied at 1.1 kg a.i./ha in each of two applications at a 60-day interval (less than recommended rate) effectively controlled large crabgrass (≥93%), regardless of turfgrass species. Pendimethalin applied at 1.1 kg a.i./ha in each of two applications controlled large crabgrass in common bermudagrass effectively (≥90%) but not large crabgrass in tall fescue (47%). The difference in pendimethalin performance between the two species was attributed to the ability of common bermudagrass to compete more successfully than tall fescue with large crabgrass during late summer. Chemical names used: 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethy1)-l,3,4-oxadiazol-2-(3 H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).

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A field experiment was conducted for 2 years to determine the effects of rate and time interval for repeated applications of the plant growth regulators (PGR) flurprimidol and paclobutrazol on vegetative suppression of `Tifway' bermudagrass [Cynodon transvaalensis Burtt-Davy × C. dactylon (L.) Pers.]. Suppression of vegetative growth of this grass was generally the same when either flurprimidol or paclobutrazol was applied twice after a 2-, 3-, or 4-week interval. The duration of growth suppression was also similar after initial application with flurprimidol at 0.84 kg·ha-l and repeated at 0.28 to 0.84 kg·ha-1 or with paclobutrazol applied initially at 1.1 kg·ha-1 an d repeated at 0.56 to 1.1 kg·ha-1. Both PGRs caused slight to moderate turfgrass injury at these rates, but the injury was temporary and the grass had fully recovered by 10 weeks. Chemical names used: α -(1-methylethyl)- α -[4-(trifluoromethoxy)-phenyl]-5-pyrimidinemethanol (flurprimidol); (±)-(R*R*) β -[(4-chlorophenyl)-methyl]- α -(1,1-dimethylethyl)-1H-1,2,4-triazole-l-ethanol (paclobutrazol).

Free access

Abstract

Several slow-release nitrogen (N) sources, applied as single spring treatments at 98 kg N/ha, were compared to a single application of water-soluble N in April at 98 kg N/ha or 49 kg N/ha applied in April and repeated in June to evaluate their effect on centipedegrass [Eremochloa ophiuroides (Munro) Hack.] performance. In spring, Escote 100, IBDU (fine, isobutylidene diurea), sulfur-coated urea (SCU) and SCU + AN provided color equal to NH4NO3 (AN), but only treatments containing SCU produced turfgrass quality equal to AN. During the summer, all slow-release N carrier treatments provided turfgrass quality and color that was equal to or better than that provided by AN. Ureaform (UF) resulted in better late fall color than did AN, but fall quality ratings were similar regardless of N source. Thatch accumulation was similar for all treatments and no centipede decline was observed. Leaf N content was not markedly influenced by treatment and no consistent trend in relative growth rate among N sources was apparent. Thus, while no single slow-release N source provided a season-long advantage over AN applied in April, all could be used effectively on centipedegrass.

Open Access
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A turfgrass wear injury study was conducted at Griffin, Ga., on `Tifway' bermudagrass (Cynodon dactylon × C. transvaalensis) using two golf car tires and three golf car types driven in a semicircular pattern to deliver 85 passes over the tread path plot area. Wear injury for the 14 days after wear was applied was assessed by visual quality, percent green coverage, leaf bruising, and verdure. Golf tire × car interactions occurred, but more wear occurred with the low pressure (48 × 103 Pa), dimpled tread tire with flexible sidewalls than the commonly used bias ply (4-ply), V-shaped tread tire with more rigid sidewalls. Significant differences in wear damage occurred for golf car type but were influenced by tire design. Thus, selection of golf car tire and golf car type can influence the degree of wear injury on turfgrass sites.

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Creeping bentgrass (Agrostis palustris Huds.) putting greens are commonly infested with crabgrass (Digitaria spp.) and goosegrass [Eleusine india (L.) Gaertn.]; however, many herbicides have the potential to severely injure this turfgrass species. A field investigation was conducted over 2 years to determine the tolerance of creeping bentgrass to various herbicides. Trifluralin plus benefin (2.2 to 6.7 kg·ha-1), dithiopyr (0.37 to 1.1 kg·ha-1), and prodiamine (0.5 to 1.7 kg·ha-1) did not injure creeping bentgrass. Pendimethalin caused only slight injury when applied at 3.4 kg·ha-1, but injury increased in 1 of 2 years when applied at ≥6.7 kg·ha-1. Creeping bentgrass was severely injured when treated with benefin plus oryzalin (≥4.5 kg·ha-1), fenoxaprop (0.07 kg·ha-1), and oxadiazon (3.4 kg·ha-1) granular and WP formulations and, therefore, should not be applied to the turf. Chemical names used: N -butyl-N -ethyl-2, 6-dinitro-4-(trifluoromethyl) benzenamine (benefin); S,S -dimethyl 2-(difluoromethyl-4-(2-methylpropyl)-6-(trifluoromethyl-3, 5-pyridinedicarbothioate (dithiopyr); (±) 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid (fenoxaprop); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); 3-[2,4-dichloro-5-(l-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N -(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); 2,4-dinitro N,N -dipropyl-6-(trifluoromethyl)-1,3-benzenediamine (prodiamine); 2,6-dinitro-N-N -dipropyl-4-(trifluoromethyl)benzenamine (trifluralin).

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Abstract

Turfgrass wear tests were conducted at Griffin, Ga. in 1985 and 1986 on ‘Tifway’ bermudagrass (Cynodon dactylon × C. transvaalensis) using several golf car tire designs (tread configurations, radial or non-radial), golf cars, and traffic patterns. Wear damage to bermudagrass in all studies was assessed by visual turf quality, color, verdure, and leaf bruising. Golf car traffic caused significant wear damage regardless of golf car, tire design, or traffic pattern. Damage increased with frequency of trips over the site and with moderately sharp turns. Differences in wear injury between the tire designs did occur, but were minor in most instances. These differences could not be explained by tread pattern alone, since similar designs gave different degrees of wear. Whether the tire was radial or not did not influence turfgrass wear. Golf car type exhibited a minor effect on bermudagrass wear. Management alternatives to minimize turfgrass wear should concentrate on distributing traffic and avoiding sharp turns, while selection of pneumatic tire design or golf car is of minor relative importance.

Open Access

There is significant interest from vegetable processors, growers, and consumers in organic sweet corn (Zea mays) production. Organic nitrogen (N) management is particularly challenging in high N consuming crops such as sweet corn because of the low N content and low N to phosphorus (P) ratios of organic soil amendments. Various management programs were compared to determine the optimal combination of soil amendments and green manure crops for organic sweet corn production. Alfalfa (Medicago sativa), rye (Secale cereale), and field pea (Pisum sativum) were used as green manure crops. Composted poultry manure and a high N content organic fertilizer were used as organic amendments. Ammonium nitrate was used in a conventional management program for comparison. Treatments were designed to deliver a full rate of N (150 lb/acre), a half rate of N (75 lb/acre), and to limit the amount of P applied. Phosphorus can become a source of pollution when applied to erodible soils, particularly when soils already contain excessive P. Sweet corn yield in many of the organic programs was highly variable among years while the yield was more consistent in the conventional program. This was attributed to differences in organic N mineralization in both the green manure crops and the amendments. The most stable yield from an organic treatment, among years, was achieved using the commercially available organic N fertilizer. Commercially available amendments were costly, and although organic sweet corn received a premium price in years when organic yields were lower, profit was reduced by the high cost of N management.

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