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Regina P. Bracy and Richard L. Parish

Stands of brassica crops obtained with precision seeders are sometimes inadequate or nonuniform. Although several types of covering devices and presswheels are available from precision seeder manufacturers, the effects of covering devices and presswheels on plant emergence of direct-seeded Brassica crops have not been determined. In Spring and Fall 1996, six crops of mustard [Brassica juncea (L.) Czerniak] and four crops of cabbage (Brassica oleracea L. capitata group) were direct seeded with a precision belt seeder using four covering devices and four rear presswheels. All of the covering devices and presswheels evaluated were adequate for direct seeding mustard and cabbage under the soil moisture conditions and soil type (silt loam or fine sandy loam) found in these experiments. Although poor stands were obtained with all seed covering devices and presswheels when 7.8 inches (199 mm) of rain occurred within 3 days of planting, plant stand of cabbage was greater when the paired arm device was used than with drag-type or no covering devices.

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Regina P. Bracy and Richard L. Parish

Stanhay, Carraro, and Gaspardo precision vegetable seeders were evaluated for seeding uniformity with seeds of five vegetable crops—cabbage (Brassica oleracea L. Capitata group), carrot (Daucus carota L.), cucumber (Cucumis sativus L.), onion (Allium cepa L. Cepa group), and spinach (Spinacia oleracea L.). Five measurements [mean, percentage of misses, percentage of multiples, quality of feed, and precision (defined as the coefficient of variation after misses and multiples were discarded)] were used to evaluate seeder uniformity. Using all five measurements provided a more complete determination of the metering uniformity of the seeders than was possible in prior work when only mean and coefficient of variation were used. The belt seeder (Stanhay) was effective at singulating spherical seeds (cabbage) and nearly spherical seeds (onion)as the most precise vacuum seeder (Carraro). Seeding uniformity of all seeders with elongated (carrot and cucumber) or angular (spinach) seeds was inadequate for precision seeding.

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Yan Chen, Ronald E. Strahan, and Regina P. Bracy

Yellow nutsedge (Cyperus esculentus) is one of the most troublesome and widespread perennial weeds infesting landscape plantings in the United States. Few selective herbicides are available for managing this weed. A combination of organic mulch with preemergence herbicide may improve control efficacy at tuber emergence and reduce the need for subsequent postemergence applications. However, limited information is available on potential interactions between herbicide placement and mulching and their effect on yellow nutsedge control and landscape plant growth and quality. In this study, control efficacy of preemergence herbicide s-ethyl dipropylthiocarbamate (EPTC) applied at 0, 4, or 6 lb/acre above or under pine straw, pine nuggets, or shredded cypress mulches were evaluated in landscape beds infested with yellow nutsedge and planted with ‘Mystery’ gardenia (Gardenia jasminoides), ‘Stella de Oro’ daylily (Hemerocallis), and ‘Big Blue’ liriope (Liriope muscari). Pine nuggets provided greater yellow nutsedge control compared with shredded cypress during the first 6 weeks after treatment (WAT) in mulch-alone plots. All mulch-alone plots had similar yellow nutsedge shoot densities and were 40% to 60% less than untreated bare soil plots from 6 to 12 WAT. Control efficacy was greater when EPTC was applied under mulch compared with above-mulch applications regardless of mulch products. In addition, EPTC at low rate resulted in similar control as high rate when applied under mulch. No injury was observed on any ornamental plants treated with EPTC. Mulching improved growth, flowering, and overall visual quality of gardenia, but reduced number of flowers in daylily and aboveground biomass in liriope at some sample dates though their visual qualities were unaffected. Based on these preliminary data, EPTC applied preemergence before mulching a new landscape bed or replenishing an existing bed can improve yellow nutsedge control without injuring selected ornamental plants.

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Regina P. Bracy, J.F. Fontenot, and R.J. Constantin

Brassica juncea var crispifolia was stored in perforated polyethylene bags, polyolefin heat-shrinkable films, and nonbagged at 1, 4, or 15C during three experiments in the spring of 1989 and 1990. Bagging mustard in perforated polyethylene bags or polyolefin films of Cryovac D-955 60-gauge or Cryovac D-955 100-gauge significantly reduced weight loss over nonbagged mustard. Bag type had a highly significant effect on CO2 concentrations in the atmosphere within bags of mustard, with highest CO2 concentrations occurring in the bags made of Cryovac film. Mustard stored in all bags retained marketable quality significantly better than nonbagged mustard. Bagged mustard was stored for 12 days at 1 or 4C with excellent quality, whereas nonbagged mustard was unacceptable after only 5 days in storage. Color, turgor, and appearance of all mustard were poor after 5 days in storage at 15C. Sensory evaluations indicated bagging and storing mustard for 12 days at 1 or 4C did not affect the flavor and quality of cooked mustard.

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Regina P. Bracy, Richard L. Parish, and Roger M. Rosendale

Application uniformity of fertilizers and pesticides is critical for crop uniformity, but can be difficult to determine when a fertilizer or chemical (fertigation/chemigation) is applied via drip irrigation or deep irrigation tape. Three injectors (venturi, pump, and proportional) were compared in a greenhouse experiment with a continuous-injecting experimental plot injector for fertilizer distribution uniformity in a drip irrigation system. Injection rate and solution volume were evaluated in a field experiment. Injection rate had a significant effect on fertilizer distribution uniformity. Better fertilizer distribution in the greenhouse experiment was obtained with venturi and proportional injectors. In the field, better distribution was obtained with the 1 gal/min (0.06 L·s-1) positive-displacement pump than with the 3 gal/min (0.19 L·s-1) pump. Injection times were longer with these injectors than with the other treatments, with the exception of the continuous injector. Injectors tested in this experiment will give uniform fertilizer distribution if the injector is properly sized with the water flow rate of the system.

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Regina P. Bracy, Richard L. Parish, and E.B. Moser

Field studies were conducted in Fall 1991 and 1992 to determine 1) if cauliflower (Brassica oleracea L. Botrytis Group) could be precision-seeded to a stand without subsequent thinning and 2) the optimum seed spacing necessary to directly seed cauliflower to a stand. Seed spacings of 10, 20, and 30 cm at one seed per hill and 30 cm at two seeds per hill were evaluated for effect on yield, head weight, plant population, and early harvest percentage. As evaluated in the laboratory, seeder precision (accuracy) was good in regard to seed counts and spacing measurements at the various seed spacings. In the field, seeder precision varied in distribution patterns among seed spacings and years. Cauliflower directly seeded at one seed per hill and a 20-cm spacing produced yields and head weights similar to cauliflower seeded 10 cm apart and thinned to 30 cm—the seeding method currently used by some commercial operators.

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Richard L. Parish, Regina P. Bracy, and Hershel F. Morris Jr.,

A study was conducted to evaluate the effect of banding or broadcasting fertilizer on yield and quality of turnip (Brassica rapa L. Rapifera group), sweetcorn (Zea mays var. rugosa Bonaf), and cabbage (Brassica oleracea L. Capitata group). Preplant fertilizer was applied broadcast prior to bedding, broadcast after bedding, or banded after bedding. Sidedress applications were broadcast or banded on the beds. Strong visual differences were noticed early in the season in the spring turnip crop with the growth in the broadcast-then-bed treatment appearing superior. The yield at first harvest and total yield were lower for turnip growth with the bed-and-broadcast treatments. No differences in yield of cabbage and sweetcorn resulted from the treatments. Few differences in turnip stem to leaf ratio were noted due to fertilizer treatment. Few differences in yield due to sidedress method were noted with any of the crops. Since broadcasting can be done with a faster, wider applicator, growers could reduce costs by broadcasting fertilizer and obtain yields that are at least equivalent to the yields from banding.

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Regina P. Bracy, Richard L. Parish, and Joe E. McCoy

Precision vegetable seeders were found to have unexpected variation in seed spacing uniformity. A belt seeder and vacuum seeder were evaluated using cabbage (Brassica oleracea L. capitata group) seeded at different seed spacings to determine if seeder uniformity improved with increasing seed spacing. Seeding uniformity of the belt seeder was not affected by seed spacing, but uniformity of the vacuum seeder was. Variation in seed spacing with the vacuum seeder was consistent in absolute units, thus seed spacing nonuniformity (expressed as a percentage of theoretical spacing) decreased with increasing seed spacing. Operating the vacuum seeder with the air pressure seed release mechanism disengaged improved seeder precision. Uniformity and precision of the belt seeder were better than that of the vacuum seeder.

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Regina P. Bracy, R.L. Parish, and W.A. Mulkey

A cultural system consisting of precision seeding on shaped beds, followed by cultivation using mechanically guided equipment, was developed and evaluated with several vegetable crops. The precision cultural system allowed for growing the crops at high plant populations by using precision planting and exact cultivation of multiple narrow rows of plants on wide beds. Eight field experiments were conducted from 1987 to 1989 on broccoli (Brassica oleracea var. botrytis L.), cabbage (Bra&a oleracea var. capitata L.), mustard (Brassica juncea var. crispfolia L.), and spinach (Spinacia oleracea L.) to evaluate production of these crops on single- and multiple-row configurations on narrow (1 -m) and wide (2-m) beds. The precision cultural system was assessed to be an excellent method for production of the small-seeded crops that were tested. Yield was highest for cabbage, mustard, and spinach planted in six rows on 2-m beds compared with four-, two-, or one-row beds. Multiple-row configurations did offer yield advantages over the single-row configuration for broccoli production.

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Yan Chen, Regina P. Bracy, Allen D. Owings, and Joey P. Quebedeaux

Use of controlled-release fertilizers (CRF) has been recommended to the landscape service industry as a best management practice for establishing landscape plants. However, application practices vary considerably among professionals and recommendations are lacking for the appropriate type (tablet vs. granular), application rate, and timing of CRF to establish herbaceous perennials. In this study, cigar plant (Cuphea ignea), daylily (Hemerocallis ‘Stella de Oro’), gaura (Gaura lindheimeri ‘Siskiyou Pink’), lantana (Lantana camara ‘New Gold’), mexican heather (Cuphea hyssopifolia), purple coneflower (Echinacea purpurea), and rudbeckia (Rudbeckia fulgida ‘Goldsturm’) were fertilized with granular CRF (GF) 15N–3.9P–10K (8 to 9 month) at 0, 1, 2, or 4 lb/1000 ft2 nitrogen (N) at transplant (no fertilization, GF1, GF2, and GF4, respectively), a split application of GF with 1 lb/1000 ft2 N applied at transplant and 1 lb/1000 ft2 N applied 5-months later (GF2-split), or tablet CRF 16N–3.5P–10K (8 to 9 months) at two tablets per plant (7.5 g) at transplant (TF2). Plant size and visual quality (VQ) at 5 months after transplant (MAT) were improved by fertilization for all perennials except ‘Stella de Oro’ daylily. Compared to GF2, GF4 improved the growth of perennials of larger size and greater biomass production (i.e., cigar plant), but did not further improve their VQ. All perennials grown with TF2 had similar size and quality as those grown with GF2 at 5 MAT. At 15 MAT, no difference was found among fertilizer treatments for surviving perennials except cigar plant. Split application (GF2-split) did not improve overwinter survival or second-year plant growth and quality for most species when compared with GF2. On the basis of these results, we recommend applying two tablets (7.5 g) of 16N–3.5P–10K per plant at transplant to establish the perennials tested in this study.