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Matthew J. Koch and Stacy A. Bonos

, 1999 ). Breeding turfgrasses for increased salinity tolerance requires an efficient screening method. First, the method must allow for the ability to quickly screen large numbers of plants. Second, cost and labor requirements must also be considered

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Huangjun Lu and Richard Raid

screening methods are labor-intensive and thus allow only a small number of cultivars to be tested at a time. For example, Carisse et al. (2000) evaluated only nine cultivars and Bull et al. (2007) tested 16 cultivars. Breeding lettuce for BLS resistance

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J.M. Turner and K.K. Tanino

On average, one year in ten is a true test winter for screening winter hardy plants. Thus, screening of cultural practices under field conditions is often difficult, requiring many years data. In Saskatchewan, the two major winter stresses are low temperature and desiccation. Under controlled lab conditions, a rapid screening method for cultural practices on strawberry (Fragaria × ananassa Duch.) plants was developed. Temperature profiles and survival under various row covers and mulches in this controlled system corresponded well to previous field results. Straw over plastic and snow over plastic row covers conferred the best low temperature protection on these plants.

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Vincent V. Michel, Nicole Debrunner, and Xavier Simonnet

rapid greenhouse screening method for the identification of st. john’s wort accessions that are resistant to anthracnose caused by C. gloeosporioides . Materials and Methods Accessions. Of the 26 st. john’s wort accessions tested, 19 were used for both

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Monte L. Nesbitt, J.B. Storey, S.D. Lyda, and L.J. Grauke

Phymatotrichum Root Rot, caused by Phymatotrichum omnivorum (Shear) Duggar, imposes severe losses upon dicotyledonous horticultural crops in the southwestern United States and northern Mexico. Rootstock resistance could benefit pecan (Carya illinoensis) production in affected growing areas; however, erratic growth habit of this pathogen and site variability prevents effective field screening. We have developed a containerized screening method for horticultural crops, using a commercial soilless growing medium. In sterile cultures, 2.5 × 60 cm glass tubes containing Metro Mix 500 yielded more grams of P. omnivorum sclerotia than cultures grown in Houston Black Clay, a traditional medium for cotton research. Preliminary screening with Okra (Abelmoschus esculentus) in non-sterile Metro-Mix 500 resulted in 75% mortality of inoculated plants in 30-35 days. Preliminary screening with 12-week-old, open-pollinated `Apache' and `Moore' pecan rootstocks has resulted in 25% mortality of inoculated plants in 150 days. Pecan seedlings with visible taproot infection appear to delay mortality by adventitious root formation.

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D.L. Hopkins and J.W. Harris

Screening for resistance to Elsinoe ampelina (de Bary) Shear, causal agent of grape anthracnose, in grapevine seedlings is commonly conducted by natural infection over 3 to 4 years in the vineyard. The objective of this research was to develop a greenhouse screening method for selecting grapevine seedlings with resistance to anthracnose. Spores of E. ampelina were obtained from 3- to 4-week-old cultures on potato dextrose agar. Inoculum concentrations ranging from 1.3 × 103 to 1.3 × 107 E. ampelina conidia per mL were evaluated and 106 conidia/mL was optimum. The time of incubation of seedlings in a moist chamber after inoculation varied from 24 to 120 hours with 24 to 72 hours resulting in good symptom development. Temperatures in the moist chamber from 16 to 32 °C were evaluated and the most consistent results were obtained at 20 to 28 °C. The most effective method for selecting anthracnose-resistant grape seedlings in the two-to-three true-leaf stage was misting the seedlings with a suspension containing 106 conidia/mL in water and placing the inoculated seedlings in a moist chamber at 24 °C for 48 hours, followed by 8 days on a greenhouse bench. Resistant seedlings from the greenhouse screening (those with <10 foliar lesions) were transplanted into the vineyard and found to be resistant to anthracnose infection under rainy, humid conditions. This greenhouse procedure for selecting grapevine cultivars and breeding lines with resistance to anthracnose is accurate, economical, and labor-saving.

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Paul C. St. Amand and Todd C. Wehner

Gummy stem blight (Didymella bryoniae (Auersw.) Rehm) is one of the major cucumber diseases, causing the second highest loss of any disease in North Carolina. Published methods of screening for resistance to this fungus are poorly correlated with field resistance. The objective of this study was to develop seedling or detached-leaf screening methods that are correlated with field resistance. Seedling tests examined the effects of: seedling age (1, 2 or 3 true leaves), days in humidity chamber, inoculum concentration (1×105, 1×106 or 1×107 spores per ml), time of inoculation (am vs. pm), fungal isolates, and cultigens. Detached leaf tests examined the effects of leaf age (1st, 2nd or 3rd true leaf), inoculum concentration (1×104, 1×105 or 1×106 spores per ml), and light levels during incubation (dark vs. 12h light/12h dark). Correlations between seedling tests and field data were moderate to high (r = 0.5 to 0.7). However, the coefficients of variation were also high. Correlations between detached leaf tests and field data were very low or negative.

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Ockert Greyvenstein, Terri Starman, Brent Pemberton, Genhua Niu, and David Byrne

before they can be applied effectively. Currently, no rapid laboratory screening method has been developed for phenotyping high temperature susceptibility in garden roses. The objectives of the study described herein were to develop a rapid screening

Open access

Thomas M. Kon, Melanie A. Schupp, Hans E. Winzeler, and James R. Schupp

, J.A. 2005 Application of ammonium thiosulfate for blossom thinning in apples Scientia Hort. 104 161 168 Kon, T.M. Schupp, M.A. Winzeler, H.E. Schupp, J.R. 2020 Screening thermal shock as an apple blossom thinning method. II. Pollen tube growth and

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Thomas M. Kon, Melanie A. Schupp, Hans E. Winzeler, and James R. Schupp

thinning strategies: A USA perspective Hort. Rev. 46 255 298 Kon, T.M. Schupp, M.A. Winzeler, H.E. Schupp, J.R. 2020 Screening thermal shock as an apple blossom thinning method. I. Stigmatic receptivity, pollen tube growth, and leaf injury in response to