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John R. Teasdale and J. Ray Frank

Abstract

Five field experiments compared weed control systems for snap bean (Phaseolus vulgaris L.) production in 25-cm rows including herbicides, but no cultivation, to systems for conventional 91-cm rows including both herbicides and cultivation. Herbicide combinations of EPTC + dinoseb each at 3.4 kg/ha, EPTC at 3.4 kg/ha + bentazon at 0.8 kg/ha, and trifluralin at 0.6 kg/ha + bentazon at 0.8 kg/ha provided excellent control of annual weeds and yellow nutsedge in most experiments. With the most effective herbicide treatments, weed control was similar in 25-cm and 91-cm rows. However, when herbicide treatments failed to control all weed species, weed control in 91-cm rows was better than that in 25-cm rows, because 91-cm rows were cultivated. Snap beans in 25-cm rows yielded an average of 25% higher than snap beans in 91-cm rows (plant density was equivalent at both row spacings). As weed control improved, the magnitude of the yield difference between 25-cm and 91-cm row spacings increased.

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Craig A. Dilley, Gail R. Nonnecke, and Nick E. Christians

Corn gluten meal (CGM), a by-product of corn wet-milling, has weed control properties and is a N source. The weed control properties of CGM have been identified in previous studies. The hydrolysate is a water soluble, concentrated extract of CGM that contains between 10% to 14% N. Our objective was to investigate corn gluten hydrolysate as a weed control product and N source in `Jewel' strawberry production. The field experiment was a randomized complete block with a factorial arrangement of treatments with four replications. Treatments included application of granular CGM, CGM hydrolysate, urea, urea and DCPA (Dacthal), and a control (no application). Granular CGM and urea were incorporated into the soil at a depth of 2.5 cm with N at 0, 29, 59, and 88 g/plot. Plot size was 1 × 3 m. Percent weed cover data on 12 Aug. showed plots receiving the 29 g N from CGM hydrolysate had 48% less weed cover than the control (0 g). Plant growth variables showed similar numbers of runners and runner plants among all nitrogen sources.

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S.L. File, P.A. Knight, C.G. Gilliam, D.B. Reynolds, and R.L. Harkess

Non-target herbicide losses pose environmental concerns for nurseries. Therefore, the objective of this research was to determine the ability of each alternative mulch to suppress weed growth when compared to traditional chemical methods. Uniform quart liners of Lagersroemia indica × faurei `Natchez' were planted in 15-gal containers 15 June 1999, on a gravel container pad using overhead irrigation. Weed pressure was uniform. Treatments include Regal 0-0 3 G (3 lb ai/a) as a broadcast or individual container application, recycled newspaper pellets (1 inch thick), Spin-out coated recycled newspaper pellets (1 inch thick) geotextile disks (Spin-out coated), kenaf mulch, waste tire crumbles, wheat straw (2 inches thick), oat straw (2 inches thick), cereal rye straw (2 inches thick), paper mill sludge (2 inches thick), a handweeded control, and a weedy control. Treatments were organized in a RCBD consisting of eight single-plant replicates. The geotextile disks, newspaper pellets treated with spin-out, and shredded rubber tire treatments all had better than 80% weed control from 30 to 180 DAT. These alternative weed control methods can provide a good alternative to conventional weed control practices in large container-grown ornamental.

Open access

John R. Teasdale and Daniel Colacicco

Abstract

The efficacy and economics of several weed control systems for fresh market tomato (Lycopersicon esculentum Mill. ‘Pik Red’) production were compared in a 3-year field experiment. Nearly perfect weed control for 7 weeks after transplanting was required to achieve maximum yields. The increased profits associated with maximum yields more than compensated for the additional costs required to achieve optimal weed control. Under Maryland conditions, black polyethylene mulch in combination with a pretransplant incorporated application of napropamide plus pebulate and a posttransplant directed application of paraquat plus metribuzin provided the most consistent weed control and highest profit. Other profitable treatments included black polyethylene mulch in combination with other posttransplant herbicides, or with cultivation and handweeding. Treatments without black polyethylene, including a pretransplant incorporated application of napropamide plus pebulate followed by a postransplant application of metribuzin and/or cultivation, provided good weed control but did not result in yields or profits as high as those treatments with black polyethylene in 2 out of 3 years.

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Yahya K. Al-Hinai and Teryl R. Roper

This experiment was conducted to determine temporal and spatial weed management characteristics for tart cherry orchards. Annual ryegrass and lambsquarter were planted in tree rows of a 14-year-old tart cherry orchard. Vegetation was controlled with nonresidual herbicides (Gramoxone + B-1956) either all season, May, June, July, August, before harvest, after harvest, or not controlled. Shoot growth measurements showed significantly more growth by trees without weed competition during the entire season, May, June, and before harvest compared to the weedy control and postharvest, July, or August treatments. Weedy early season plots reduced the shoot growth by half. All season, before harvest, May, and June weed-free plots showed higher amounts of leaf N compared with weedy controls or late-season treatments. Early season weed control is more important than late season. Vegetation-free areas of 0, 2, 3, and 4 m2 were maintained during 1998 by postemergence herbicides. Tissue analysis showed higher N concentration in leaves with vegetation controlled to 2 m2 or more compared to the weedy control. The critical vegetation free area for young cherry trees is between 0 and 2 m2.

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John J. McCue, James R. Schupp, and Highmoor Farm

The growth and fruiting of 10-year-old `Mcintosh'/M.7 apple trees were compared under the following weed management systems: 1)untreated control; 2) herbicide spray (paraquat + oryzalin); 3) rotary tilling applied in May, June and July; 4) rotary tilling plus herbicide (oryzalin); 5) rotary tilling plus oats sown in August. All weed control methods increased tree growth compared to the untreated control over three years. Yield and fruit size were increased by the herbicide and the rotary tilled treatment. Rotary tilling plus herbicide increased yield but fruit size was larger than controls in 1990 only. Rotary tilling plus oats produced yield and fruit size equivalent to the control. In 1989 and 1990 rotary tilling alone provided less weed control compared to the herbicide treatment, while in July 1991, the reverse was true. Rotary tilling with herbicide and with oats have demonstrated weed control comparable to or better than the herbicide treatment except for the rotary tilled plus oats treatment in 1990. There were no differences among treatments in fruit color, maturity and percent soluble solids.

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J.W. Van Sambeek and John E. Preece

Hybrid poplar is traditionally established using dormant stem cuttings in tilled soils followed by chemical or mechanical weed control. In 1996, we initiated a study to evaluate the effects of site preparation and four weed control treatments on growth and morphology of three hybrid poplar clones established on a 0.2-ha tall fescue field in southern Illinois. Site preparation included application of 2000 kg/ha of 12N-12P-12K. The experiment was arranged as a split-split plot. Main plots were closely mowed tall fescue or tilled to remove the grass sod. Within each main plot, weed control treatments were applied to 1-m wide strips in rows 2.4 m apart. Weed control treatments included porous black film, solid black film, and solid white film, and a control treatment of 3.7 L/ha of glyphosate applied each spring. On 15 Apr. 1996, three 25-cm-long dormant stem cuttings from each of three clones were randomly planted 15 cm deep every 1.8 m within each row. Clonal differences existed after the first year for survival, number of stems, stem height, stem basal diameter, and stem volume, but not for number and total length of lateral branches. Nearly all tree growth measurements analyzed during the first 3 years had a highly significant interaction between type of site preparation and method of weed control. With polyethylene films, tree survival exceeded 90% on both the tilled ground and grass sod sites after 3 years; however, with the herbicide treatment survival averaged only 18% in the grass sod and 51% in tilled soil. Excluding the herbicide treatment, tree growth was better in the grass sod than in the tilled soil. Tree growth using porous black polyethylene film was usually less than that with either of the two solid polyethylene films. The best tree growth was found with a grass sod and solid white polyethylene film for weed control.

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Jacqueline A. Ricotta and John B. Masiunas

Black polyethylene mulch and weed control strategies were evaluated for potential use by small acreage herb producers. In both 1988 and 1989, the mulch greatly increased fresh and dry weight yields of basil (Ocimum basilicum L.) and rosemary (Rosmarinus officinalis L.). Parsley (Petroselinum crispum Nym.) yield did not respond to the mulch. Preplant application of napropamide provided weed control for 2 weeks, but was subsequently not effective on a heavy infestation of purslane (Portulaca oleracea L.). Hand-hoed and glyphosate-treated plots (both with and without plastic) produced equivalent yields. Chemical names used: N, N -diethyl-2(1-napthalenoxy)-propanamide (napropamide); N- (phosphonomethyl) glycine (glyphosate).

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Charlotte Herman and Emily Hoover

The objective of our study was to establish first year strawberry plantings without using herbicides. `Honeyoye' transplants were set into plots measuring 6.1m × 7.32m on 21 May, 1993. Four treatments were established: winter wheat, a dwarf Brassica sp., napropamide (2.24kg/h), and no weed management. After the strawberry plants, cover crops (and some weeds) were fairly well established, (18 June) 6 week-old African “weeder” geese were put into half of each plot to graze. Weekly data was taken on the percentage of soil area covered with plant material, height and stage of development of plants, and weeds present. A weed transect was done in 6 July. Plant material was collected from each plot on 26 July and 16 Sept. in a 0.2m2 area, and dried. The most promising cover crop treatment was the dwarf Brassica for early season weed control. However, the herbicide treatment with no geese produced the best strawberry plant growth.

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Derek M. Law, A. Brent Rowell, John C. Snyder, and Mark A. Williams

A 2-year field study in Lexington, Ky., evaluated weed control efficacy and influence on yields of several organic mulches in two organically managed bell pepper (Capsicum annuum) production systems. Five weed control treatments [straw, compost, wood chips, undersown white dutch clover (Trifolium repens) “living mulch,” and the organically approved herbicide corn gluten] were applied to two production systems consisting of peppers planted in double rows in either flat, bare ground or on black polyethylene-covered raised beds. In the first year, treatments were applied at transplanting and no treatment was found to provide acceptable season-long weed control. As a result, bell pepper yields in both production systems were very low due to extensive weed competition. First year failures in weed control required a modification of the experimental protocol in the second year such that treatment application was delayed for 6 weeks, during which time three shallow cultivations were used to reduce early weed pressure and extend the control provided by the mulches. This approach increased the average weed control rating provided by the mulches from 45% in 2003 to 86% in 2004, and resulted in greatly improved yields. In both years, polyethylene-covered raised beds produced higher yields than the flat, bare ground system (8310 lb/acre compared to 1012 lb/acre in 2003 and 42,900 lb/acre compared to 29,700 lb/acre in 2004). In the second year, the polyethylene-covered bed system coupled with mulching in-between beds with compost or wood chips provided excellent weed control and yields. When using the wood chip mulch, which was obtained at no cost, net returns were $5587/acre, which is similar to typical returns for conventionally grown peppers in Kentucky. Net returns were substantially decreased when using compost due to the purchase cost. Results from this study indicate that shallow cultivation following transplanting, combined with midseason mulch application, resulted in high yields in an organically managed bell pepper system that were comparable to yields of most varieties grown conventionally in a variety trial conducted on the same farm.