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Casimir A. Jaworski and Sharad C. Phatak

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G.H. Neilsen, E.J. Hogue, T. Forge and D. Neilsen

`Spartan' apple (Malus×domestica Borkh.) trees on M.9 (T337) rootstock were planted in April 1994 at 1.25 m × 3.5 m spacing. Seven soil management treatments were applied within a 2-m-wide strip centered on the tree row and arranged in a randomized complete-block experimental design. Treatments included a weed-free strip (check) maintained with four annual applications of glyphosate; surface application of 45 t·ha-1 of Greater Vancouver Regional District (GVRD) biosolids applied in 1994 and again in 1997; mulches of shredded office paper; alfalfa (Medicago sativa L.) hay; black woven polypropylene; and shredded paper applied over 45 t·ha-1 GVRD-and Kelowna-biosolids applied in 1994 and 1997. All experimental trees were fertigated with phosphorus (P) in the first year and with nitrogen (N) annually. Cumulative yield for the first five harvests was higher for trees subjected to any soil management treatment relative to check trees. Maximum cumulative yield, exceeding check trees by 80%, was measured for trees grown with a shredded paper mulch with or without biosolids application. Trees from the three shredded paper treatments were the only ones significantly larger than check trees after six growing seasons. No increases in leaf nutrient concentration were consistently as sociated with improved tree performance. Notable effects included increased leaf P concentration associated with biosolids application, increased leaf K concentration after alfalfa mulch application and temporary increases in leaf Zn and Cu concentration associated with application of biosolids high in Zn and Cu. Use of both mulches and biosolids amendments benefits growth of trees in high density plantings despite daily drip irrigation and annual fertigation.

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Eugene J. Hogue, John A. Cline, Gerry Neilsen and Denise Neilsen

allelopathic and biofumigant properties have been introduced ( Barnes and Putnam, 1983 ; Reberg-Horton et al., 2005 ). Ground covers, sometimes referred to as “living mulches,” have become popular in organic orchards in particular ( Hartwig and Ammon, 2002

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David R. Bryla, Thomas J. Trout and James E. Ayars

garlic in Winter to Summer 2006. Fertilization, thinning, and weed and pest control were done following standard cultural practices for the region. The fraction of ground covered or shaded by vegetation ( f c ) in the lysimeter was measured periodically

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N.R. Rice, M.W. Smith, R.D. Eikenbary, D.C. Arnold, W.L. Tedders, B.W. Wood, G.G. Taylor, B.S. Landgraf and G.E. Barlow

Annual legume ground covers were evaluated in pecan (Carya illinoinensis) orchards to supply nitrogen and increase beneficial arthropods. Treatments were established at two sites, each with 5 ha of a `Dixie' crimson clover (Trifolium incarnatum) /hairy, vetch (Vicia villosa) mixture and 5 ha of grass sod. Data indicated that the legume mixture supplied over 100 kg·ha-1 N to the pecan trees. Beneficial arthropods were greater in orchards with legume ground covers than in orchards with a grass groundcover. Lady beetles and green lacewings were the most important spring predators, and green lacewings were the most important fall predator. The Species distribution on the ground covers differed from that in the canopy. Coleomegilla maculata lengi, Hippodamia convergens and Coccinella septempunctata were the most abundant lady beetle species in the legume ground covers, and Olla v-nigrum, Cycloneda munda, and Hippodamia convergens were the most abundant species in the pecan canopies. Beneficial arthropods appeared to suppress injurious pecan aphids.

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D.M. Glenn and W.V. Welker

We determined how differences in peach tree water use and shoot and root growth due to ground cover treatments are affected by tree response and soil conditions in the adjacent soil environment. Ground cover combinations of bare soil (BS), a killed K-31 tall fescue sod (KS), a living Poa trivialis sod (PT), and a living K-31 tall fescue sod (LS) were imposed on 50% of the soil surface in greenhouse studies. The ground cover on 50% of the soil surface influenced root and top growth of the peach trees [Prunus persica (L) Batsch], water use, and NO3-N levels in the opposing 50%, depending on the competitiveness of the cover crop (LS vs. PT and KS) and characteristics of the soil (BS vs. KS). Tree growth was allometrically related to root growth.

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Lee F. Johnson, Michael Cahn, Frank Martin, Forrest Melton, Sharon Benzen, Barry Farrara and Kirk Post

. Pereira, L. 2009 Estimating crop coefficients from fraction of ground cover and height Irr. Sci. 28 17 34 Bottoms, T. Smith, R. Cahn, M. Hartz, T. 2012 Nitrogen requirements and N status determination of lettuce HortScience 47 1768 1774 Bryla, D. Trout, T

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DeFrank and Charles R. Clement

Pejibaye (Bactris gasipaes, Palmae) is being evaluated for palm heart production in Hawaii. Counts of parasitic nematodes and yields at 18 months and weed control were evaluated in response to: Arachis pintoi, Cassia rotundifolia cv. Wynn, Desmodium ovalifolium, Chloris gayana, and woven black polypropylene mat. Four open-pollinated progenies from the Benjamin Constant population of the Putumayo landrace were used as replications. Twenty five percent of the plants were harvested, with means of 5, 20, 15, 15, and 70%, respectively. Individual heart weights did not vary significantly among treatments (mean = 169 g). Actual yields were significantly different, with means of 31, 125, 92, 99, and 440 kg/ha, respectively. All vegetative ground covers competed with pejibaye for nutrients, which explains the harvest percentages and yields. D. ovalifolium and C. gayana provided acceptable weed control. A. pintoi provided good ground cover, but reduced weed control.

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H.H. Bryan, A.A. Abdul-Baki, L. Carrera, G. Zinati and W. Klassen

Ground covers in orchards and living mulches in vegetable fields can be effective in reducing weed control costs and loss of water and nutrients from the soil, fixing N, and adding organic matter to the soil. Several accessions of rhizoma (perennial) peanut were evaluated in 1999, 30 months after planting, at the farm of the Tropical Research and Education Center, Univ. of Florida, Homestead, in gravelly, calcareous soil with a pH of 7.5. Evaluation criteria included adaptability (plant vigor, rhizome growth, and biomass yield), weed suppression, N-fixation, nutrient content, leaf density, and Fe chlorosis. Accessions that survived exhibited major differences in the evaluation criteria. Accessions No. 6968 and 4222 (recently named `Amarillo') showed promising potential for use as ground cover and a living mulch in vegetable fields in southern Florida.

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Roberto Nunez-Elisea, Helen Cahn, Lilia Caldeira and Clark F. Seavert

Black, woven polypropylene row covers were compared to chemical sprays as methods to manage ground vegetation in a `Regina'/Gisela 6 orchard planted in 2001. Row covers were installed within 1 month of planting. Exposed row cover width was 2.4 m, with edges (30 cm on each side) buried in the ground. Only a 30-cm band along the edge of row covers was sprayed with herbicide to facilitate mowing. Weed management of control trees consisted of chemical herbicide sprays. Trees were not fertilized since planting in 2001. Irrigation of all trees was applied with low volume (20 L·h-1) microsprinklers and scheduled according to soil water content. Row covers significantly increased trunk cross-sectional area (TCSA) by about 30% annually. By Summer 2004, trees with ground covers had filled their allotted space within rows, while control canopies were ≈50 cm apart. Trees in row covers produced a 130% higher average yield than controls (7.4 kg/tree vs. 3.2 kg/tree). Row covers produced larger and firmer fruit, which matured 2–3 days later than controls. Groundcovers slightly increased soil temperature from April to September by ≈2 °C at 5- and 10-cm depths. Roots under ground covers were denser and more spread out than in controls and water use efficiency was higher for trees growing in ground covers. Amount and labor for herbicide application was reduced to less than half with row covers. Although ground covers are expensive at ≈$2000 per acre, their cost could be offset by earlier and higher production and by long-term savings in labor, water use, and herbicides. Durability of row covers is expected to exceed 15 years.