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Eric T. Stafne

In 2005, 212 ha of grapes were grown in Oklahoma and more than 30 licensed wineries were in operation. With this increase in grape growing and wine making comes the necessity to evaluate commercially appropriate cultivars. `Rubaiyat' was a cross between Seibel 5437 and `Bailey' made at Oklahoma State University by Herman Hinrichs in 1952. The overall genetic constitution of `Rubaiyat' (based on disomic inheritance) is 37.5% V. lincecumii, 31.25% V. vinifera, 18.75% V. labrusca, 6.25% V. rupestris, and 6.25% V. riparia. `Rubaiyat' is a dark blue-black grape that ripens in mid-August. The berries are medium-sized and round. The clusters are medium in size with a long shoulder. The vine has medium vigor and good to very good disease resistance. The juice is very dark red with about 19% sugars and tartaric acid levels of 0.63%. The wine is fruity and has good balance. A slight “foxy” flavor from the V. labrusca is sometimes evident in wine made from `Rubaiyat'. Currently, other hybrid grape cultivars such as `Chambourcin' are more popular for use as red wine varietals than `Rubaiyat'. However, in observation trials in Oklahoma, `Rubaiyat' compares favorably to `Chambourcin' in quality and may outyield it. Perhaps the greatest potential for `Rubaiyat' is as a teinturier, since it has the attribute of red flesh derived from its progenitor `Alicante Bouschet', a parent of `Alicante Ganzin'. `Rubaiyat' is not widely grown, but the potential exists for it to become an important cultivar for Oklahoma and surrounding states.

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Haijun Zhu and Eric T. Stafne

Paclobutrazol (PBZ) was applied to 6-year-old pecan (Carya illinoinensis) trees as a basal trunk drench (0, 30, 90, and 150 mg·cm−2 trunk cross-sectional area) in Dec. 2012. Terminal shoot growth was retarded for 1 year after a single application of PBZ. The total number of current season shoots showed a significant increase with 30- and 90-mg·cm−2 PBZ treatments. After PBZ application at 30, 60, and 90 mg·cm−2, the percentage of very short shoots (<5 cm) was 32.3%, 36.3%, and 32.3%, respectively, compared with 22.4% on control trees; the percentage of short shoots (5–15 cm) increased to 36.0%, 38.1%, and 43.5%, respectively. The percent of long shoots (>30 cm) was decreased to 7.4%, 5.1%, and 7.6%, respectively, after PBZ application, compared with 18.7% with control. Shoots varying from 5 to 30 cm in length accounted for at least 63.3% of all pistillate inflorescences the following spring.

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Amir Rezazadeh and Eric T. Stafne

The present study assessed the effect of photoperiod on budbreak of cuttings of three interspecific hybrid grape (Vitis) cultivars that had received different chilling hours. Stem cuttings were collected at 100-hour intervals of chilling (200, 300, 400, 500, 600, 700, and 800 hours) from the vineyard and kept in three growth chambers with daylengths of 8, 16, and 24 hours. Another group of cuttings were maintained in a greenhouse with a natural daylength range of 10.5–13 hours [8 Dec. 2017 to 4 May 2018 (average = 12 hours)]. Chilling requirements, days to budbreak, and budbreak rate were determined after plants were exposed to different chilling hours and daylengths. Results of our study demonstrated that the chilling requirements of all three cultivars were adequately reached at 600 hours or more. Increasing chilling exposure from 600 to 800 hours shortened the time to budbreak in all cultivars. Overall, ‘MidSouth’ had an average budbreak rate of 90% when receiving at least 600 hours chilling. ‘Blanc du bois’ and ‘Lake Emerald’ had 62% and 65% average budbreak, respectively. Longer days (24 hours) reduced time to budbreak by 14, 6, and 8 days, respectively, in ‘Blanc du bois’, ‘Lake Emerald’, and ‘MidSouth’ at 600 hours chilling. A combination of 24-hour photoperiod and chilling of 600 hours resulted in a maximum budbreak rate of 70%, 70%, and 100% in ‘Blanc du bois’, ‘Lake Emerald’, and ‘MidSouth’, respectively. Our results indicate that breaking dormancy may be controlled by both temperature and photoperiod in these three cultivars.

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Eric T. Stafne and John R. Clark

In a database system that allows for quick and accurate querying, PediTrack generates pedigrees in an easily understandable format. Other pedigree programs are available commercially, but are often expensive, specific to certain organisms, or unadaptable for specific programmatic use. PediTrack allows a personal computer (PC) user with Microsoft Access version 2000 or higher to use the simple program without charge. This software is widely available and easily adaptable to a variety of breeding program functions. PediTrack does not perform any calculations, so the initial program size is small (<2 megabytes). The program consists solely of the basic framework for housing pedigree information and reporting pedigrees based on those records.

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Eric T. Stafne and Kathleen D. Kelsey

Junior college (JC) and community college (CC) programs offering viticulture and enology courses have proliferated in recent years in many states, especially outside of traditional grape growing regions. A survey was sent to 69 land-grant (LG) horticulture, viticulture, and enology specialists who may interact with JC and CC programs offering viticulture and enology courses. Forty answered for a response rate of 58%. Results indicated that most LG horticulture/viticulture programs are not interacting with the JC/CC programs and that LG specialists do not believe the education received by students of the JC/CC program is sufficient to create well-trained industry professionals. JC/CC programs are generally regarded as positive for the viticulture and enology industry by LG specialists, but some question the quality of instruction. Many LG respondents do not believe the JC/CC programs are impacting their own programs and do not see the JC/CC programs as competitors to their programs; however, documented actions of JC/CC programs would dictate otherwise, especially in the area of Cooperative Extension programming. LG viticulture and enology programs should no longer consider JC/CC programs as noncompetitors for funding and clientele interaction, especially in states with limited resources. LG programs should seek to develop appropriate partnerships with JC/CC programs to benefit the viticulture and enology community. However, any collaboration must be mutually beneficial, well-designed, well-coordinated, and conducted with reciprocal respect for each program.

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Eric T. Stafne, Charles T. Rohla and Becky L. Carroll

Pecan (Carya illinoinensis) shells are waste products that are occasionally used for mulch in ornamental landscape settings, yet most shell waste is left in piles near the shelling facility or discarded by other methods. If another use for this waste product could be developed, it may add income for pecan producers and provide peach (Prunus persica) growers with another option for weed control. A block of ‘Loring’ peach trees grafted onto ‘Halford’ rootstocks was planted at a spacing of 18 × 22 ft in Feb. 2005 at the Cimarron Valley Research Station near Perkins, OK, to determine the effect of pecan shell mulch on peach trees. Five treatments were imposed: no weed control except mowing (MOW), weed-free 6- × 6-ft area maintained with glyphosate herbicide (SPRAY), 6-ft × 6-ft × 2-inch deep mulch (TWO), 6-ft × 6-ft × 4-inch deep mulch (FOUR), and 6-ft × 6-ft × 6-inch deep mulch (SIX). Yields in 2008 were poorest in the MOW treatment (13.2 kg/tree and 93 fruit/tree). All other treatments did not differ. Soluble solids concentration as a measure of fruit quality and fruit weight was unaffected by treatment. Tree height, pruning weights, and trunk cross-sectional area were similar with the exception that MOW was lower for all three growth measurements beginning in 2007. Pecan mulch appears to have the potential to reduce soil pH. Foliar analysis for nitrogen (N), potassium (K), and zinc (Zn) showed treatment differences in 2006. No treatment differences were evident in 2007 and 2008 for K and Zn, but in 2008, FOUR had greater N than MOW. Tree mortality increased with pecan mulch depth. MOW, SPRAY, and TWO had little tree loss (0%–5%), whereas FOUR and SIX had 15% and 35% mortality, respectively. Tree mortality was attributed to record rains in 2007 coupled with longer soil moisture retention under the deeper mulch.

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Chrislyn A. Particka, Eric T. Stafne and Timothy E. Martinson

Webinars have become an important aspect of many extension outreach programs, especially for large research projects that cover wide geographic regions. Evaluation of webinar impact is important to funders and stakeholders alike. Surveys to gather direct and indirect data can be used to evaluate webinars for their overall utility. The results can inform funders of program success and also serve as an indicator of the continued viability of webinar programming for extension audiences. The Northern Grapes Project administered a webinar series on topics related to grape (Vitis sp.) and wine production from 2012 through 2016. Thirty webinars were delivered to an audience of 3083, with nearly an additional 2400 views of recorded webinars. To estimate the value of the series, we modified two models, one that estimated viewer time investment and one that calculated the “green savings.” In addition, we surveyed webinar participants, asking them how much they would pay to watch a live webinar and access the archives, as well as how much money they had earned and/or saved from the information presented. Together, the models and survey indicated a webinar series value of nearly $3.4 million.

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Eric T. Stafne, John R. Clark and Kim S. Lewers

A tetraploid blackberry population that segregates for two important morphological traits, thornlessness and primocane fruiting, was tested with molecular marker analysis. Both randomly amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers were used to screen a population of 98 genotypes within the population plus the two parents, `Arapaho' and `Prime-Jim' (APF-12). RAPD analysis averaged 3.4 markers per primer, whereas SSR analysis yielded 3.0 markers per primer pair. Similarity coefficient derived from the Dice index averaged over all individuals was 63% for RAPD markers, 73% for SSR markers, and 66% for RAPD and SSR markers together. The average similarity coefficients ranged from a high of 72% to a low of 38% for RAPD markers, 80% to 57% for SSR markers, and 73% to 55% for both. Comparison of the parents indicated a similarity of 67% for RAPD markers, 62% for SSR markers, and 67% for both. This is similar to a previous study that reported the similarity coefficient at 66%. Although inbreeding exists within the population, the level of heterozygosity is high. Also, evidence of tetrasomic inheritance was uncovered within the molecular marker analysis. This population will be used to identify potential markers linked to both morphological traits of interest. Further genetic linkage analysis and mapping is needed to identify any putative markers.

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Stanta Cotner, John R. Clark and Eric T. Stafne

A study was conducted in the Winter–Spring 2004 to evaluate the effects of seed (pyrene) scarification period on blackberry (Rubus L. subgenus Rubus) genotypes that had a range of seed weights. The study was done in an attempt to identify optimum scarification period for variable seed weights for the purpose of increasing germination of blackberry seeds produced from hybridizations in the Arkansas blackberry breeding program. Scarification treatments of 1, 2, or 3 hours were used on 14 genotypes. Seeds were then stratified for 3.5 months and sowed on a commercial potting medium in a heated greenhouse. Germinating seedlings were counted over a 15-week period and total germination determined. Data analysis indicated significant genotype effect on germination but no scarification treatment nor genotype × scarification treatment interaction significance. The results indicated that scarification period did not affect germination and varying this period predicated on seed weight was not beneficial based on the genotypes used in the study.

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Eric T. Stafne, John R. Clark and Curt R. Rom

Seven Rubus cultivars were evaluated at two locations in Arkansas, northwest (Fayetteville) and southwest (Hope), to evaluate plant growth differences under high and very high summer temperature conditions. Temperatures during the hottest month (July) averaged 34 °C and 38 °C for Fayetteville and Hope, respectively. Growth; leaf area and number; and fresh and dry weights of leaves, stems, and roots were measured on the containerized raspberry cultivars Autumn Bliss, Dormanred, Heritage, Nova, Reveille, and Southland and the blackberry cultivar Arapaho. Growth measurements included number of canes per plant, number of laterals per cane, cane length, node number, and internode length. Measurements were taken monthly from June through September. Leaf areas were done after all growth measurements were taken at both locations in September. Variation occurred among cultivars and locations for leaf area, fresh and dry weights, growth, and leaf number. Plant death occurred at the Hope location, with `Heritag', `Reveille', and `Southland' all having plant mortality, while `Dormanred' and `Arapaho', both southern-adapted cultivars, had the greatest fresh and dry weights. The Fayetteville location had no plant loss after initial emergence in spring, and this more moderate environment probably contributed to higher plant survival. Our data indicated that only `Dormanred' and `Arapaho' achieved adequate survival and growth in the very high temperatures of the Hope location, whereas other cultivars (Reveille and Southland) with some southern U.S.-adapted germplasm, showed poor adaptation to the environments of our study. Our findings reflect the impact of high heat on non-adapted germplasm and reveal information on adaptation levels needed for parental consideration in breeding for southern conditions.