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  • Author or Editor: Robert Martin x
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Abstract

Viruses consist of nucleic acid packaged in a protective shell composed of protein or, in some cases, protein plus lipid. This shell protects the nucleic acid from enzymatic degradation while it is outside the host cell in a potentially hostile environment. Recent advances in virus detection and diagnosis are based on increased sensitivity of methods for the detection of proteins and nucleic acids.

Open Access
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Cuttings from Rubus ursinus Cham. & Schlecht, the trailing blackberry, were collected in Oregon, Washington, and British Columbia from 21 sites. The cuttings were rooted and placed in pots in the greenhouse. After the plants began to grow, leaves were harvested for ELISA testing using standard procedures. Each sample represented three clones from a site. Plants from 18 sites were represented by five samples and two sites were represented by three samples. None of the samples tested positive for the presence of raspberry bushy dwarf virus or tomato ringspot virus. Forty-four percent of the samples tested positive for tobacco streak virus. Only 33% of the sites on the Pacific coast tested positive for tobacco streak, whereas, 100% of the Cascade Mountain sites and 88% of the sites in the coastal range type environment tested positive. The only site in the Willamette Valley had no positive tests. With one exception, all of the sites that tested negative for the virus were also low elevation sites 0-90 m.

Free access

The Pennsylvania State University Medieval Garden (PSMG) showcases varieties of medieval plants used as ornamentals, food crops, medicinal ingredients, and for household purposes in a stylized setting representing a medieval garden. Since its installation, various colleges within the university as well as community groups have used the garden as an alternative classroom for learning activities, educational demonstrations, and events related to the medieval period. This article focuses on the initial development of the garden design and how the installation and continued use as a classroom has contributed to meeting educational goals for students in the landscape contracting program at the Pennsylvania State University and the Pennsylvania Governor's School for Agricultural Sciences.

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Abstract

In the paper “Determination of moisture in walnut seeds by near-infrared spectrophotometry” by Robert C. Campbell and George C. Martin, (HortScience 11(5):494. 1976), two errors on page 495 have been noted.

Open Access

Precocious varieties of highbush blueberry may over-crop during the first few seasons in the fruiting field, adversely affecting plant establishment. Reducing or preventing bloom in the nursery and during establishment would be beneficial in preventing early cropping and reducing the risk of infection by pollen-borne viruses. We investigated the efficacy of foliar applications of ProVide® (Valent BioSciences), a commercial GA4+7 formulation, for suppressing flower bud initiation in blueberry. One-year-old rooted cuttings of `Bluecrop' were obtained from a commercial nursery and established in 11-L pots at the Blueberry and Cranberry Research Center, Chatsworth, N.J. Dilute foliar applications of ProVide® were made at concentrations ranging from 50 to 400 mg·L-1 a.i., ranging from 7 July to 1 Sept. 2004, with 10 replicate plants per treatment. Floral and vegetative buds were counted the following spring. A separate experiment was initiated in 2005, with concentrations of 200 and 400 mg·L-1 a.i. applied in August and September. For the 2004 study, the greatest flower bud suppression resulted from repeat applications at 400 mg·L-1 a.i. Weekly applications from 7 July to 1 Sept. resulted in a 70% reduction in flower bud number, whereas three weekly applications from 18 Aug. to 1 Sept. reduced flower bud number by >88%. Neither treatment significantly reduced total bud numbers (vegetative + floral) compared to untreated and water-sprayed controls, indicating that the treatments did not reduce plant growth. Results for the 2005 treatments will also be presented.

Free access

Abstract

A method is described for the rapid determination of percent water in walnut seed by use of near-infrared spectrophotometry.

Open Access

Quercus falcata acorns were cold-stratified for 120 days and then sown in vermiculite under greenhouse conditions. When radicles were 7 cm long, the root tip was either removed (physically pruned) or dipped in a copper hydroxide solution (copper-treated). Intact root systems were used as control. Seedlings were then moved to a root box to observe root system architectures. The box was built of clear plexiglass 2.5 mm thick, and each face was 25.7 × 35.7 cm. Styrofoam spacers were used to separate faces, and nuts and bolts were placed along edges to hold the root box together. To permit observation of the entire root system, plants were grown in a plane between the plexiglass surface and a nylon sheet that separated roots from the medium (MetroMix 510). At 7, 9, and 11 days after treatment, the entire root system was traced on an acetate sheet, and number of internal and external links and number of secondary and tertiary roots were recorded. Total length, internal and external root links length, were obtained using digital analysis (MacRhizo). Dry weight of roots and shoots was collected at the end of this experiment (day 11). Treatment effects were evident 11 days after treatment. Copper-treated plants had statistically more secondary roots and larger internal link length than control or physically pruned plants. Also, copper-treated plants had smaller mean external link length, showing a more branched root system. Root biomass was similar for all treatments; however, copper-treated plants had smaller root: shoot ratio. This suggests that copper was acting as more than a pruning agent because copper-treated plants showed a different root system architecture compared to physically pruned plants.

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Eighty-seven highbush blueberry and species-introgressed blueberry cultivars were evaluated for fruit firmness in the 1998-2000 growing seasons with a FirmTech 1 automated firmness tester. Significant differences were observed among cultivars. An average firmness of 136.1 g·mm-1 of deflection (g·mm-1 dfl) was observed across all studied cultivars, and a range of 80.4 g·mm-1 dfl (`Herbert') to 189.0 g·mm-1 dfl (`Pearl River'). Species ancestry was not consistently related to firmness; however, cultivars with higher firmness values often possessed a higher percentage of Vaccinium darrowi Camp and V. ashei Reade ancestry. Conversely, cultivars with softer than average fruit often possessed a higher percentage of lowbush (V. angustifolium Ait.) ancestry. This information may help to identify sources of breeding material for increased firmness in highbush blueberry hybrids.

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Abstract

In two consecutive growing seasons, extracts of prune flower and fruit tissue were bioassayed for hormonal activity. High levels of GA-like and neutral auxin-like compounds were evident in seed extracts in midseason during the period of rapid embryonic growth. An ABA-like inhibitor increased in the pericarp as maturity approached, while GA-like activity fell to negligible levels.

Open Access

Effects of VAM fungal inoculum, Glomus intraradices Schenk & Smith, on the growth of Chilean mesquite in containers were investigated as part of a nursery container system for production of xeric trees. Seedling liners of Chilean mesquite were transplanted into 27-liter containers filled with a 3 pine bark : 1 peat moss : 1 sand medium. Before transplanting, 50% of the trees were band-inoculated at a depth of 8 to 12 cm below the growth medium surface with 35 g per container of Glomus intradices (Nutrilink, NPI, Salt Lake City, UT), approximately 1,000 spores g-1. All trees were top-dressed with 15 g Osmocote 18N-2.6P-9.9K (Grace-Sierra, Milpitas, CA) and 3 g Micromax (Grace-Sierra, Milpitas, CA) fertilizers and grown in a fiberglass greenhouse under 50% light exclusion. After 4 months, all inoculated tree root systems were colonized, and the percent infection was 47%. Noninoculated trees remained nonmycorrhizal. There were no differences in height, total shoot length, shoot dry weight, or root dry weight between inoculated and non-inoculated trees; however, total root length and specific root length of inoculated trees were less than those of noninoculated trees. These results suggest that the VAM fungi altered the root architecture of inoculated trees such that root systems of these trees had thicker roots with fewer fine roots elongating into the growth medium profile.

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