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  • Author or Editor: Curt Rom x
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The NE-183 project was established in 1993 and the first trial planted in 1995 with the objective of evaluating new apple cultivars for horticultural, pest and disease resistance, and qualitative characteristics. Arkansas (AR) is the southernmost location for the initial planting. The following cultivars are in AR trial: `Arlet', `Braeburn', `Cameo', `Creston', `Enterprise', `Fortune', `Fuji', `Gala Supreme', `Ginger Gold', `GoldCrisp', `Golden Delicious', `Golden Supreme', `Goldrush', `Honeycrisp', `NY75414-1', `Orin', `Pristine', `Sansa', `Shizuka', `Suncrisp', `Sunrise', and `Yataka'. Bloom of `Braeburn', `Yataka', `Orin', `Gold Supreme', `Fortune', and `Enterprise' were early and may be exposed to annual spring frosts. The following cultivars ripened in July or August and may be too early for southern markets: `Pristine', `Sunrise', `Sansa', `Ginger Gold', `Arlet', `Honeycrisp', `Golden Supreme', and `Orin'. The following cultivars were very precocious and had yields >7.5 kg/tree in the third growing season: `Fuji', `Enterprise', `Creston', `Golden Delicious', `Ginger Gold', `Suncrisp', and `Goldrush'.

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In 1995, greenhouse and orchard experiments of 11 apple cultivars were conducted in Fayetteville and Clarksville, Ark. Weekly cumulative mite days (CMD) were regressed against leaf bronzing (colorimeter value L) and compared among cultivars. European red mites, Panonychus ulmi and two-spotted spider mites, Tetranychus urticae, were found on leaves. `Liberty', `Royal Gala', and `Stark Spur Red Rome Beauty' had significantly more mites (>1940 CMD) than did `Arkansas Black' (1303), `Jonafree' (1150), and `Northern Spy' (973). A low CMD on `Northern Spy' caused leaves to bronze faster [y = 29.04 + 0.006(x); R 2 = 52, P = 0.0002] than did a high CMD on `Liberty' [y = 30.41 + 0.0027(x); R 2 = 70, P = 0.0001]. Field estimates were made of spider mites/leaf and bronzing from 20 June to 7 Aug. `Stark Spur Red Rome Beauty' and `Stark Spur Law Rome' had significantly more CMD than did `Northern Spy' and `Arkansas Black'. Apple cultivars differed in carrying capacity to mites (susceptibility) and how fast leaves bronze in response to mite feeding. Cultivar differences in hairiness of the lower leaf surface were not correlated to CMD.

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The genus Betula consists of approximately 50 deciduous species throughout northern hemisphere. Net CO2 assimilation ([A]) of four birch taxa (Betula alleghaniensis Britton, B. davurica Pall., B. nigra L. `Heritage', and B. papyrifera Marsh.) was measured with a portable gas exchange system, CIRAS-I. Light was increased from 0 to 2000 μmol· m-2·s-1 at increments of 25, 50, 100, 250, 500, 750, 1000, 1250, 1500, 1750, 2000 μmol·m–2·s–1 to create an [A] light-response curve. CO2 concentration was gradually increased to 1100 ppm in increments 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100 ppm to create an [A]-Ca (ambient CO2) curve. B. davurica had significantly higher potential A capacity than the other taxa under high CO2 conditions. Betula nigra `Heritage' had the highest carboxylation efficiency among four taxa. B. davurica and B. nigra `Heritage', had higher [A] when ambient CO2 is 0ppm. Betula davurica and B. nigra `Heritage', had higher light-saturated rate of gross [A] than B. alleghaniensis and B. papyrifera.

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Fruit production in the Southern region has declined in the last several decades. Further, although certified organic fruit production has increased significantly in other regions of the US in the past decade, there has been very little growth of that industry in this region. It is presumed that the lack of production is based upon the lack of research, out-reach, and science-based information available to growers which make organic production possible. Based on planning grant funding from the Southern IPM Center program and the Sustainable Agriculture Research and Education program a Southern Organic Fruit Working Group is being formed. The projects are collaborative efforts of horticulturists, entomologists, plant pathologists, soil scientists, and agricultural economists in Arkansas, Georgia, Kentucky, North Carolina, South Carolina, and Tennessee. In each state, a coordinator is hosting stake-holder focus groups of producers, marketers, processors, extension workers, consultants, organic certifiers, etc. The purpose of focus group meetings is to identify challenges and opportunities in production and marketing organic fruit, especially apples, blackberries, blueberries, and peaches, in the Southern Region. Coordinators are combining findings from state focus group meetings to establish priorities for research and outreach to support organic production, and will work collaborative to addresses those priorities. Because of the similarity in climate, geography and demographics of growers and markets among the states of the region, this is a project best addressed as a regionally collaborative effort.

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The highly weathered, mineral, and often eroded and acidic soils of the Ozark Highlands region of northwest Arkansas generally have low soil organic matter (SOM) concentrations as a result of rapid organic matter turnover rates in the warm, moist climate. Orchard management practices that can improve SOM may also improve other soil quality-related variables for sustained production, which is an explicit goal for the National Organic Program (NOP). Therefore, beginning in Mar. 2006 and continuing for seven seasons, annual applications of municipal green compost, shredded office paper, wood chips, and mow-blow grass mulch groundcover management systems (GMS) in combination with composted poultry litter, commercial organic fertilizer, or a non-fertilized control as a nutrient source were implemented to evaluate their ability to alter near-surface soil quality in a newly established, organically managed apple orchard in the Ozark Highlands region of northwest Arkansas. The SOM concentration in the top 10 cm averaged 1.5% across all treatments at orchard establishment in 2006, but by 2012, SOM concentration had increased in all GMS and more than doubled to 5.6% under green compost. Similarly, soil bulk density in the top 6 cm, which averaged 1.34 g·cm−3 among treatment combinations in 2006, decreased in all GMS by 2012. Either green compost or shredded paper had the largest concentration of total water-stable aggregates across all aggregate size classes in the top 7.5 cm, whereas no differences among GMS were observed in the 7.5- to 15-cm soil depth. Green compost applied alone or in combination with commercial fertilizer had the largest estimated plant-available water (17.9% v/v) among all treatment combinations. Many soil quality-related variables measured in the various organic GMS had numerically greater values compared with an adjacent conventionally managed orchard on the same soils. Implementation of these GMS appears to provide apple producers in the Ozark Highlands and similar regions a tangible means of meeting NOP requirements for improving soil quality concurrent with production of certified organic crops. The findings also have implications for conventionally managed orchards, which have maintaining or improving soil quality as a management goal.

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Extending the production season of blackberry (Rubus subgenus Rubus) cultivars allows producers the opportunity to potentially receive better prices. Producers could benefit from out-of-season production by sustaining cash flow during more of the year and thereby expanding their market. The objective of this study was to compare the present value (PV) probabilities of being able to cover the total cost (TC) of production (break-even) for open-field and high tunnel production systems for the primocane-fruiting blackberry cultivar Prime-Jan® in northwestern Arkansas. (PVs) of gross revenues (GRs) of each production system were simulated 500 times. Total yields were higher in the open-field system in the first 2 years of production and consistently higher in weeks 33 to 34 and 36 to 37 than high tunnel production. It seems that there are no yield benefits from the high tunnel system early in the harvest season, except in the first year of primocane-fruiting production. The break-even probability was sensitive to the different percentage of yield sold, the percentage of the retail price received by the producer, and the production system analyzed. Even though the potential gross returns obtained with the high tunnel system are high (when compared with open-field production), the PV distributions of the gross returns do not offset the high tunnel TC in half of the simulations. Conversely, open-field production proves to be more profitable both in magnitude and in terms of the likelihood of exceeding the break-even threshold over the productive life of the enterprise.

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Insecticides were compared for control of codling moth (Cydia pomonella) and oriental fruit moth (Grapholita molesta), and effects on european red mites (Panonychus ulmi) and predatory mites (Neoseiulus fallacis) in `Red Delicious' apple trees (Malus ×domestica). Ten days after treatment with azinphosmethyl, celerylooper (Anagrapha falcifera) nuclear polyhedrosis virus, rotenone-pyrethrin, or codling moth granulosis virus, fruit damage by larval codling moth and oriental fruit moth was significantly less than trees treated with Bacillus thuringiensis var. kurstaki or water (control). Trees treated with azinphosmethyl or celery looper nuclear polyhedrosis virus had fewer damaged fruit where larvae exited than did other treatments. By 21 days after the last treatment, all treatments had significantly more wormy or damaged fruit than did azinphosmethyl. At 10 days after treatment, the two viruses were more deleterious to codling moth than to oriental fruit moth causing a <1:3 ratio of these larvae compared to >3:1 ratio for the other treatments. On 16 June, 100 predatory mites were released onto the trunk of each tree. The minimum ratio of predatory mites to european red mites (>1:10) that favors biological control of european red mites occurred in all treatments by 14 July, except those treated with azinphosmethyl or rotenone-pyrethrin that had significantly more cumulative mite days of european red mites than the other treatments. The use of azinphosmethyl delayed biological control of the european red mites until 27 July whereas rotenone-pyrethrin treatment never attained biological control of the mites.

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Abstract

Source–sink relationships in sweet cherry were altered by girdling limbs both above and below fruiting spurs. Spurs isolated by girdling both above and below had lower total fruit weight per spur and lower weight per fruit then those above or below girdles. Fruit number per spur was not altered, but soluble solids and fruit color were lower in fruits from isolated spurs than fruit from spurs either above or below girdles. Fruit on spurs above girdles were generally highest in soluble solids and fruit color. These factors indicate fruit on isolated spurs also were delayed in maturity. Spurs below girdles were unaffected by girdling. Girdling had no effect on spur leaf net photosynthesis, stomatal conductance, or fruit water loss rate. The results indicate that spur leaves alone do not have the capacity to support fruit growth in sweet cherry and must, therefore, be supplemented by photosynthates from other sources.

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Net CO2 assimilation (A) of four birch genotypes (Betula nigra L. ‘Cully’, B. papyrifera Marsh., B. alleghaniensis Britton, and B. davurica Pall.) was studied under varied photosynthetic photon flux density (PPFD) and CO2 concentrations (CO2) as indicators to study their shade tolerance and potential for growth enhancement using CO2 enrichment. Effect of water-deficit stress on assimilation under varied PPFD and (CO2) was also investigated for B. papyrifera. The light saturation point at 350 ppm (CO2) for the four genotypes varied from 743 to 1576 μmol·m−2·s−1 photon, and the CO2 saturation point at 1300 μmol·m−2·s−1 photon varied from 767 to 1251 ppm. Light-saturated assimilation ranged from 10.4 μmol·m−2·s−1 in B. alleghaniensis to 13.1 μmol·m−2·s−1 in B. davurica. CO2-saturated A ranged from 18.8 μmol·m−2·s−1 in B. nigra ‘Cully’ to 33.3 μmol·m−2·s−1 in B. davurica. Water-deficit stress significantly reduced the light saturation point to 366 μmol photon m−2·s−1 but increased the CO2 saturation point in B. papyrifera. Carboxylation efficiency was reduced 46% and quantum efficiency was reduced 30% by water-deficit stress in B. papyrifera.

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