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G. Steven Sibbett

Pecan [Carya illinoinensis (Wangenh. K. Koch)] soils in the arid western United States are characteristically high in pH, calcareous, and often saline or sodic. Economic production, when trees are grown in such soils, requires that growers pay particular attention to managing soil chemistry to avoid nutrient deficiencies, toxicities, or water deficits due to soil structural deterioration. Soil-applied acidulents, calcium-containing compounds, and water management are used by growers to manage high pH problems, sodic soil conditions, and salinity.

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Marc Laganière and Yves Desjardins

At present, there is no herbicide registered for use in Canada to control annual bluegrass in sod production. Under serious infestations, aesthetic qualities are reduced and sod harvest becomes more complicated. The efficiency of propane burners to control annual bluegrass was tested in a trial initiated in Spring 1993. Specific objectives were to determine the appropriate period for treatment application and the heat intensity required for optimal control. Twenty-one plots (13 × 3 m) were treated with a conventional burner; a similar group was treated with a pipe burner. In addition to an untreated check, the combination of two tractor-burner speeds (3.6 and 5 km·h-1) and three gas pressures (20, 30, and 40 psi) made up the seven treatments. Randomized complete blocks were used and each treatment was replicated three times. The sod recovered well from all heat treatments. After 3 weeks, the best heat treatment reduced the annual bluegrass population by 70%. Unfortunately, this reduction lasted for about 1 month, after which the annual bluegrass population recovered. At best, weed population was reduced by 40% when evaluated in mid-September. Another trial is planned to identify environmental and edaphic factors that may reduce the effectiveness of heat treatments in controlling annual bluegrass in sod production.

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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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R.M. Pool, R.M. Dunst, and A.N. Lakso

In two 4-year studies, `Concord' (Vitis labruscana, Bailey) cane pruning weight, yield, and soluble solids content were similar for vines growing under herbicide and cultivation treatments. In a vineyard with shallow soil, vines grown under mulch had a significantly greater increase in cane pruning weight than did vines grown with sod middles. Growth suppression of sod-managed vines occurred only in relatively dry years. While there was annual variation in vine response to herbicide and cultivation treatments, the cumulative responses over the 4-year study were similar for these treatments. A second vineyard where soil was less restrictive for root growth did not respond to the replacement of clean cultivation with herbicide treatments. In both experiments, there was no apparent advantage of two instead of a single herbicide application, and there was no difference between the budbreak, as opposed to bloom timing, of herbicide application.

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Allen V. Barker

Major compostable materials in municipal solid wastes (MSW) are sewage sludge, paper, garbage, and autumn leaves. Five composts made from these wastes separately or in mixtures and one compost made from agricultural wastes (chicken manure and cranberry pomace) were evaluated for production of grass sods. Perennial ryegrass (Lolium perenne L. 'Pennfine') was seeded in 3.5-cm-deep layers of compost in plastic trays and grown in a greenhouse. Seed germination was inhibited in immature sludge-based and mixed MSW composts relative to germination in the other composts. High ammonium levels in the immature sludge-based and mixed MSW composts appeared to limit germination, as these composts had ammonium-N levels ranging from 1,000 to 2,000 mg/kg. Ammonium-N in the agricultural compost was 200 mg/kg, whereas that in the leaf-based composts was 10 mg/kg. In general, germination in all media was sufficient to establish a stand. Thereafter, growth of sods in the sewage-based, mixed MSW, and agricultural composts benefitted from the rich supply of N and exceeded that in the leaf-based composts. Mixing of composts with soil gave no advantage other than slightly increased seed germination but diluted total N supply and increased weediness of the sods.

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Douglas T. Linde and Lawrence D. Hepner

Using composted biosolid waste as a soil amendment for turfgrass is becoming a common method for disposing of municipal waste. This study was conducted to evaluate turfgrass seed and sod establishment on subsoil amended with various rates of biosolid compost. To a soil that had its A-horizon removed, biosolid compost derived from sewage sludge was incorporated at rates of 0, 132, 270, and 402 yard3/acre. A fifth treatment included a single application of fertilizer at time of sowing. Kentucky bluegrass (Poa pratensis) was seeded immediately after treatment application. The treatments were repeated on an adjacent area using kentucky bluegrass sod. For 1.5 years, turfgrass percent cover, color, density, and weeds were evaluated. Overall, the compost performed well as a soil amendment for turfgrass. A 2- to 3-inch depth of compost appeared to be the best incorporation rate for the soil and compost used in this study. High salinity and excessive ammonium nitrogen (NH4-N) levels in the compost-amended soil at the time of establishment caused a 2- to 3-week delay in seed and sod establishment. After the 2 to 3 weeks, the compost-amended plots outperformed the one-time fertilized plots in turfgrass color and density. Turf managers may want to account for the delay in establishment when incorporating a 60-day-cured compost.

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K.L. Hensler, B.S. Baldwin, and J.M. Goatley Jr.

A truly soilless turfgrass sod may be produced on kenaf-based (Hibiscus cannabinus L.) fiber mat that offers the integrity of field-cut sod without the use of mineral soil growing medium. This research was conducted to determine the feasibility of producing warm-season turfgrass sod on such a biodegradable organic mat. Seeded turfgrass plots contained 4.9 lb/1000 ft2 (24 g.m−2) of pure live seed planted on a 66-lb/1000 ft2 (325-g.m−2) organic fiber mat carrier placed atop either 66- or 132-lb/1000 ft2 (325- or 650-g.m−2) organic fiber mats. In an experiment using vegetative material, stolons were applied at rates of 16.4 ft3/1000 ft2 (0.82 L.m−2) over 132- or 198-lb/1000 ft2 (650- or 975-g.m−2) organic fiber mats and covered with a rayon scrim. All plots were placed on 6-mil black plastic. Nitrogen was applied at 0.9 lb/1000 ft2 (4.4 g.m−2) weekly in addition to a monthly micronutrient application. Bermudagrass (Cynodon σππ.) had quicker establishment than other grasses in the study, with stolonized and seeded plots achieving ≈100% coverage by 9 weeks in 1995 and 6 weeks in 1996, respectively. By 15 weeks after planting in 1995, the plot coverage ratings for seeded centipedegrass [Eremochloa ophiuroides (Munro) Hack. `Common'] and all stolonized grass plots of centipedegrass, zoysiagrass (Zoysia japonica Steud. `Meyer'), and St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze `Raleigh'] were 91% or higher. The results were much less favorable in 1996 than 1995 due to a later planting date and an irrigation failure.

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Edmund M. Tavernier and Robin G. Brumfield

The greenhouse, nursery, and sod (GNS) sector in the United States accounted for $10 billion in gross sales or 5% of gross farm receipts, in 1998. Despite its significant economic contributions, the sector receives little attention from policymakers. Part of the problem lies in the absence of empirical economic analysis that addresses the impact of the sector on the U.S. economy. The absence of such analysis places the sector at a disadvantage when agricultural policies are designed to address agricultural imbalances, such as farm income problems, and hinders the ability of the sector to lobby for policies favorable to GNS producers. This study provides estimates of the economic impacts of the GNS sector on the U.S. economy and quantifies the linkages between the GNS sector and other economic sectors. The results show that the sector contributed over $26 billion and $17 billion in output and value added economic activity, respectively, and over 438,000 jobs.

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S.M. Lutfor Rahman, Eiji Nawata, and Tetsuo Sakuratani

Effects of water stress at different plant ages on SOD activities were studied in two tomato cultivars. Water stress treatment decreased the leaf water potential in all stages, but reduction of leaf water potential was more rapid and pronounced in KF than TM at all DSLs (days of seedlings). After withdrawal of water stress treatment, stressed plants of TM increased leaf water potential to the values of control level in all DSLs, but in KF, leaf water potential of stressed plants were much lower than that of control plants. Effects of water stress on relative water content (RWC) of leaves at 20 DSL showed a similar tendency to that on leaf water potential. The SOD activities in both cultivars showed significant increase by water stress treatment at all DSLs, but the increase of SOD by water stress was larger in TM than in KF. This tendency was observed at all DSLs. The results may indicate that SOD activities play an important role in drought tolerance of tomato at various plant ages and suggest a possible use of SOD activities as a criterion for tomato drought tolerance.

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Amy L. Neigebauer, Greg L. Davis, Garald L. Horst, and Donald H. Steinegger

Field-grown wildflower sod has been in production for several years, but as with any crop management system, the reasoning behind the methods is not always known. One characteristic of wildflower sod production that has been debated is the height at which the plant is maintained. The above-ground shoot growth is managed to reduce the damage to plants when undercut and to allow for ease of shipping. Growers typically use a height of 7.6 cm because this is the highest height allowed by many mowers. Also, root production is the key to forming a sod that will hold together well and withstand the rigors of undercutting, lifting, storage, and transplanting. The purpose of this study was to determine the influence of cutting height on the plant's ability to produce a sod. Rudbeckia hirta L. was used as a model wildflower species and was seeded into polyvinyl chloride (PVC) tubes 10.2 cm in diameter with a depth of 60 cm to simulate a field situation. To characterize shoot and root growth, during a period of 12 weeks plants either received no clipping or continuous clipping at heights of 5.1, 7.6, and 10.2 cm. Root dry weights were measured at depths of 0-2.54, 2.54-21.7, 21.7-40.8, and 40.8--60.0 cm. Leaf area measurements of the clippings were recorded to determine productivity. Results indicated that clipping the shoots of Rudbeckia hirta caused a decrease in root biomass.