Glenn C Wright

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Chapters

• Wright, G. C. (2023). Organic Date Production. In Date Palm - CABI Crop Production Science in Horticulture. Wallingford, UK: CABI. doi:https://doi.org/10.1079/9781800620209.0011
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  Dates have been grown organically for thousands of years. Only relatively recently have certification procedures been developed to guide organic date producers. These procedures vary according to the certification authority but require at the outset the development and submission of an organic plan that describes the organic date orchard and the procedures that will be undertaken to achieve organic status. Once the decision has been made to grow organically, the planting, fertilization, cover crop establishment, and pest control steps must all be organic. Each certification authority has a list of allowed and prohibited substances that must be followed to remain organically certified. Organic procedures must continue during harvest and in the packinghouse. Fruit quality of an organic date does not appear to be inferior to a conventionally grown date, and some feel that organic dates have superior fruit quality. The economics of growing organic dates have not been studied; however, there is no doubt that the price received by the grower for organic dates is superior to that for conventional dates, which may overcome the higher cost of organic production. It is likely that organic dates will command an increasing portion of the overall date market.
• Wright, G. C. (2022). Mejhoul cultivation in the USA. In Mejhoul Variety - The Jewel of Dates(pp 171-176). Abu Dhabi: Khalifa International Award For Date Palm And Agricultural Innovation.
• Wright, G. C. (2016). Citrus Care. In Arizona Master Gardener Handbook.
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  This is finished, and in press.

Journals/Publications

• Kahn, T., Seymour, D., Roose, M., Wright, G., & Mauk, P. (2024). Breeding Program Yields New Cultivars. Citrograph, 15(3), 41-44.
• Wright, G. C. (2024). Streamlining global germplasm exchange: Integrating scientific rigor and common sense to exclude phantom agents from regulation. Plant Disease, 1-20. doi:https://doi.org/10.1094/PDIS-04-24-0745-FE
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  Plant virology was established as a discipline in the late nineteenthcentury after the discovery of a novel entity causing tobacco mosaicdisease described as “contagium vivum fluidum” (Beijerinck 1898).Since then, the field has undergone tremendous progress in understandingplant viruses and the diseases they cause. Accurate laboratorydiagnostic tools, developed for the detection and identification ofviruses and other systemic pathogens (e.g. viroids, phytoplasmas, andfastidious bacteria) in plants, have advanced our understanding ofpathogen-vector-host interactions and are regularly employed in theproduction of plants that are free from regulated pathogens. Clean plantsare crucial for the sustainable production of clonally propagated crops(Gergerich et al. 2015; Hammond et al. 2023), facilitating the safe exchangeof plant material globally, and are often the basis of national orregional certification programs. Although accurate diagnostic tools arecrucial for certification programs and for facilitating the safe exchange ofplant material, current lists of regulated pathogens contain several“phantom” agents, which impede access to that material. Phantom agentshave been associated with symptomatic plants and diseases of unknownetiology. Most are presumed to be of viral nature, yet (i) neither infectedplant material nor reference isolates are available and (ii) no sequenceinformation is accessible. The majority of the phantom agents listedamong regulated pathogens are the result of a single report that describessymptoms and/or names a purported pathogen in the scientific literature.It is worth noting that many of the agents discussed herein have only beenreported in scientific conference abstracts and proceedings and have notgone through the peer-review process. It is often futile to state the obvious,but for the purpose of this communication, it is important to rememberthat diagnosing a disease or detecting an agent that is alleged toexist but might not be real is impossible. Biological indexing is, otherthan in a very few exceptions, used to identify phantom agents. However,biological indexing is not the most appropriate of all available diagnosticstechnologies for clonally propagated crops, including thosecovered herein (Al Rwahnih et al. 2015; Bester et al. 2021; Rott et al.2017; Villamor et al. 2022). However, when symptoms develop ingrafted indicator plants, it is often impossible to determine whether theindexed agent is one of the so-called phantoms, owing to the absence of apositive control. With today’s technology, if an indicator plant showssymptoms, it would undergo analysis by high-throughput sequencing(HTS). If this process identifies a novel agent, it is unlikely to be attributedto a phantom. Instead, it would be recognized as a new pathogenof the host. As a result, phantom agents tend to persist indefinitely. In thecase of phantom agents and the disease they were named for, it is impossibleto determine whether the disease is real and, if so, whether it iscaused by a single or multiple agents or an agent known under a differentname or even whether the said agent has been eliminated from the cropbecause of extensive sanitation and testing through certification programs,or the incorporation of resistance in modern cultivars. Subject experts fromaround the globe joined efforts in reviewing the relevant literature in theirareas of expertise and prepared a list of phantom agents/diseases for10 vegetatively propagated plant genera, grouped in eight crops. Based onour collective assessment and knowledge, we recommend that phantomagents and diseases be removed from regulatory lists based on the inabilityto (i) access diseased plant material/identify an agent (isolate) and (ii)obtain sequence information that would allow for their identification andthe development of diagnostics. When we initiated this project, the coregroup of individuals named as the primary coauthors identified more than140 agents. Communications with individuals from around the globe havetriggered research efforts that have led to the identification of type isolatesfor some of these agents and characterization of others. A list of characterizedagents is provided in Table 1. Herein, we provide information onmore than 120 phantom agents/diseases for major clonally propagatedcrops and discuss why requiring their diagnosis from a biological perspectiveis unsound. Every disease/agent discussed herein fits the aforementioneddefinition of a phantom agent.
• Wright, G., Roose, M., Seymour, D., Federici, C., Siebert-Wooldridge, T., Trunnelle, K., Thomas, Z., & Kahn, T. (2024). Optimizing Lemon Production. Citrograph, 15(3), 64-69.
• Wright, G. C. (2023). Mejhoul cultivation in the USA. Acta Horticulturae, 1371, 5-8. doi:10.17660/ActaHortic.2023.1371.2
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  Dates have been grown in the United States for over 200 years. Large plantings began about 125 years ago and the ‘Mejhoul’ was imported successfully in 1927. The US ‘Mejhoul’ industry began with a 23-ha planting in 1945, near Bard, CA, and has grown to several thousand ha today. Trees are planted in several types of soils, at spacings ranging from 7.5 to 9 m2. Irrigation is by flood or pressurized systems, and most fertilization is applied via the irrigation water. ‘Mejhoul’ dates are pollinated and thinned, then bagged before harvest. Harvest begins in August and continues through October. Few pests are problematic on ‘Mejhoul’. Harvested dates are sorted for color, dried to consistent moisture, sorted again for quality, and then shipped fresh or frozen if needed. US ‘Mejhoul’ dates are exported to Canada, Australia, Mexico, and other countries, while the US imports ‘Mejhoul’ dates from Mexico, Israel, and other countries. Date consumption in the US is low but has increased by 50% since 2012 due to active marketing programs.
• Wright, G. C., Kahn, T., & Mikeal, R. (2023). Yield, packout and fruit quality results from four lemon cultivar trials in California

   

  . Acta Horticulturae, 1366, 121-130. doi:https://doi.org/10.17660/ActaHortic.2023.1366.14
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  We established four lemon cultivar trials in California in 2015. Trial locations included the cooler San Joaquin Valley, and Coastal region, and the warmer inland Southern California, and the California desert. Cultivars evaluated included ‘Limoneira 8A Lisbon’, low-seeded ‘Limoneira 8A IR1 Lisbon’, ‘Walker Lisbon’, Corona Foothills’, ‘Limonero Fino 49’, and ‘Yen Ben’. Rootstocks varied by location. In the cooler locations, ‘Walker Lisbon’ had the greatest yield, followed closely by ‘Limoneira 8A Lisbon’. In warmer areas, ‘Corona Foothills,’ ‘Limonero Fino 49’, ‘Limoneira 8A Lisbon’ and ‘Walker Lisbon’ had the greatest yield. Yields of low-seeded ‘Limoneira 8A IR1 were 20 to 50% less, depending on location, than its seeded counterpart and yields of ‘Yen Ben’ were poor at every location because of smaller tree size. In some cases, the yield differences may have been due to incompatibility between the cultivar and rootstock, or to effects of soil pH. Fruit size of ‘Limoneira 8A IR1 Lisbon’ were often larger than the others, while fruit of ‘Yen Ben’ were often quite small. There were minor differences in fruit quality among the cultivars, except for ‘Yen Ben’ that had smoother and thinner peel.
• Hu, J., & Wright, G. C. (2021). Canker and Wood Rot Pathogens in Southwest Arizona Lemon Orchards. Plant Pathology, 15. doi:https://doi.org/10.1111/ppa.13476
• Salomón-Torres, R., Ortiz-Uribe, N., Krueger, R., García-Vázquez, J. P., Cohen, Y., Wright, G. C., & Samaniego-Sandoval, L. (2022). Evaluation of Pollen Production of Common Male Date Palms Grown in the Mexicali Valley, Mexico. Agriculture, 12(8), 1248. doi:https://doi.org/10.3390/agriculture12081248
• Hu, J., & Wright, G. C. (2021). Canker and Wood Rot Pathogens in Southwest Arizona Lemon Orchards. Plant Pathology. doi:http://doi.org/10.1111/ppa.13476
• Hu, J., & Wright, G. C. (2021). First Report of Fomitopsis meliae Causing Brown Wood Rot on Living Lemon Trees in Arizona and California. Plant Disease. doi:10.1094/PDIS-11-20-2427-PDN
• Kahn, T. L., Vince, S., & Wright, G. C. (2021). Lemon Returns - Final Summary of the California Desert Lemon Trial. Citrograph, 12(3), 36-45.
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  Deciding which lemon selection to grow is an important factor in maximizing returns. This lemon trial for the California Desert, conducted from 2005-06 through 2018-19, was the first trial that collected fruit quality characteristics, yield, pack-out data and estimated cumulative returns per acre to compare the commercial potential of ten lemon selections against two California commercial standards.
• Wright, G. C., & Hu, J. (2021). Canker and Wood Rot Pathogens in Southwest Arizona Lemon Orchards. Plant Pathology, 15. doi:https://doi.org/10.1111/ppa.13476
• Wright, G. C., Lovatt, C., & Eskalen, A. (2021). Air Temperature and Stress May Lead to Pre-Harvest Lemon Fruit Drop. Citrograph, 12(4), 38-42.
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  Pre-harvest lemon fruit drop (LFD) occurs when full-sized fruit fall from apparently healthy trees. Significant economic loss can occur. We identified potential factors that might lead to LFD, including presence of fungi on the fruit and in the soil, leaf mineral deficiencies and climactic conditions. In 2018 and 2019, we collected soil, fruit and leaf samples in California and Arizona orchards, and we applied plant growth regulators (PGRs), fungicides and mineral nutrients to attempt drop reduction. In both years, neither leaf mineral nutrient concentrations nor soil and fruit pathogen sampling results correlated to LFD. Fungicide and PGR treatments applied did not affect LFD counts or orchard yields. Data suggest that temperature may be the primary cause of LFD, especially for early bloom fruit. Harvesting earlier appeared to reduce LFD, which occurred shortly after daily maximum temperatures dropped due to the reduction of the Southwestern Monsoon. With this new insight, research to determine the proper time for PGR application is needed.
• Stover, E., & Wright, G. C. (2019). Walter Tennyson Swingle: A Relentless Intellect that Transformed American Pomology. Journal of the American Pomological Society, 73(2), 129-138.
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  Walter Tennyson Swingle grew up outside of Manhattan, Kansas, attended classes at Kansas State Agricultural College (now KSU) at 15, and when he graduated at 20 he had already published 27 scientific papers in plant pathology, plant breeding and genetics. Swingle joined the United States Department of Agriculture (USDA) in 1891, and was sent to Florida to investigate diseases in orange trees. He established a USDA laboratory and began a comprehensive program to breed disease- and frost-resistant citrus. He proposed testing all known wild relatives for disease-resistance and other advantageous traits that could be introduced to improve citrus. While conducting comprehensive studies of the comparative anatomy and systematics of the orange subfamily, he discovered some new species and several new genera. His breeding originated several new categories of citrus: the tangelos, citranges and citrumelos (now critical as rootstocks), and many other intergeneric hybrids. He was an early advocate for permanent, living collections of economically important plants and their close relatives. In 1897-98, in collaboration with David Fairchild, he established the USDA's Office of Foreign Seed and Plant Introduction, and new plant introduction research facilities were set up in Miami. He was a champion for ensuring that introduced plants were disease and pest free. He conducted plant exploration, mainly in countries surrounding the Mediterranean, and among many other accessions introduced date palms, figs, table grapes, and ‘Clementine’ mandarins. He also brought in the Blastophaga wasp to pollinate Smyrna-type figs. After his retirement from the USDA, Swingle moved to Miami in 1943 and completed his treatise on the taxonomy of the citrus subfamily. “Even in his retirement, Swingle inspired a generation of students with his knowledge, curiosity of nature, and insights into plants. His simple advice to students was ‘Look and look, again and again,’ words still relevant today”.
• Wright, G. C., & Hu, J. (2019). Huanglongbing of Citrus. University of Arizona Cooperative Extension Publication, 7. doi:https://extension.arizona.edu/pubs/huanglongbing-citrus
• Bidabadi, S. S., Dehghanipoodeh, S., & Wright, G. C. (2017). Vermicompost leachate reduces some negative effects of salt stress in pomegranate. International Journal of Recycling of Organic Waste in Agriculture, 6, 1-9. doi:10.1007/s40093-017-0173-7
• Wright, G. C. (2016). The Commercial Date Industry in the United States and Mexico. HORTSCIENCE, 51(11), 1333-1338.
• Kahn, T. L., Samons, V., & Wright, G. C. (2015). When life gives you lemons, it's time to make a profit.. Citrograph, 6(3), 48-59.
• Kahn, T., & Wright, G. (2015). Update on Evaluations of Lemon Selections for the California Desert. HortScience, 50(9), S189 (Abstr.).
• Wright, G. C., & Schuch, U. K. (2015). Pomegranate Variety Trial in Arizona. HortScience, 50(9), S309 (Abstr.).
• Wright, G., & Caravetta, G. (2014). Response of Government and the Citrus Industry to the Discovery of Asian Citrus Psyllid in Arizona. Journal of Citrus Pathology, 1(1), 80.
• Schuch, U. K., Wright, G. C., & Mahato, T. (2013). Pomegranate Variety Trial in Southern Arizona.. HortScience, 48(9), 396.
• Wright, G. (2012). Date Cultivation in Arizona and the Bard Valley. J. Amer. Pom. Soc, 66(3), 110-117.
• Wright, G. (2012). Nitrogen Fertilization Guidelines for Non- bearing Medjool Date Palms. HortScience, 47(9), S305.
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• Wright, G. C. (2008). Evaluation of ten navel orange (Citrus sinensis) selections under Arizona desert conditions. Acta Horticulturae, 773, 77-82.
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  Abstract: A navel orange (Citrus sinensis) trial was established at the University of Arizona Citrus Agriculture Center, Waddell, AZ in 1999. This trial consists of the following selections: 'Beck-Earli', 'Cara Cara', 'Chislett', 'Fisher', 'Fukumoto', 'Lane Late', 'Powell', 'Spring', 'Washington' and 'Zimmerman', all on Carrizo citrange rootstock. 'Washington' is the standard cultivar selection for the local industry. Yield, packout and fruit quality data have been collected since the first harvest in 2001. 'Fisher', 'Lane Late', 'Beck-Earli' and 'Washington' have had the greatest 5-year cumulative yield, and those selections as well as 'Cara Cara' had good annual yields in 2005-06. 'Beck-Earli' and 'Chislett' have had good yields for the 2004-05 seasons. 'Beck-Earli', 'Chislett', and 'Lane Late' generally have had large fruit size over the course of the experiment. 'Zimmerman', 'Cara Cara' and 'Washington' had large fruit size in 2004-05. 'Beck-Earli' has had characteristically elongated fruit, while the rest of the selections have had more rounded fruit. Among the early-harvest fruit, 'Fisher' is the least colored, and 'Fukumoto' colors the best. 'Spring' fruit has the best color among those selections harvested late. 'Cara Cara' fruit typically has had the highest level of solids, while the late navels have lower levels of solids. Peel thickness and granulation of the selections varies depending on the year. Based on the data collected so far, 'Beck-Earli', 'Cara Cara', 'Chislett', 'Fisher', 'Fukumoto' and 'Lane Late' appear to be suitable alternatives to 'Washington' in the desert.
• Wright, G. C. (2007). AN OVERVIEW OF THE CHANGING DATE INDUSTRY IN THE UNITED STATES. Acta Horticulturae, 736(736), 47-52. doi:10.17660/actahortic.2007.736.2
• Wright, G. C. (2007). An overview of the changing date industry in the United States. Acta Horticulturae, 736, 47-52.
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  Abstract: The commercial date industry in the United States is located primarily in the Sonoran Desert of southeast California and southwest Arizona. The industry comprises about 3800 hectares, of which 78% is found in California and the rest in Arizona. While date palms were introduced to the United States by the Spaniards, small quantities were imported for experimental purposes beginning in the late 1800's, and commercial quantities were imported in the early 1900's. During this period, most imported offshoots originated from Algeria, Egypt, Tunisia and Iraq. Important varieties that were imported include 'Deglet Noor', 'Khadrawi', 'Zahidi', 'Hayany' and 'Halawy'. More recently, the 'Medjool' from Morocco was introduced. This variety is becoming increasingly popular because of its large size and high sugar content. Date palm operations are moving from areas that are under pressure from urbanization to more remote locales. Low volume drip and microjet irrigation is beginning to replace the tradition flood and basin irrigation methods. Some dates are produced using organic methods because of consumer demand. Farm operations begin in January when the trees are dethorned. Operations that occur later in the year include pollination, training the fruit arms, strand thinning, fruit thinning, supporting the arms, spreading the strands, bagging the developing fruit and harvest. Individual growers are increasingly forming cooperatives to pack the fruit at a centrally located packinghouse. At the house, fruit are graded, then packed, and placed in storage until shipment. Dates from the region are marketed by individual growers, and by the grower cooperatives, and sold to customers around the world. Palm trees are also sold for landscape purposes to customers across the United States.
• Kusakabe, A., White, S. A., Walworth, J. L., Wright, G. C., & Thompson, T. L. (2006). Response of microsprinkler-irrigated navel oranges to fertigated nitrogen rate and frequency. Soil Science Society of America Journal, 70(5), 1623-1628.
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  Abstract: Microsprinklers allow precise control of irrigation water applications and offer the potential for higher efficiency of water and fertilizer use compared with flood irrigation. A field experiment was conducted during 1999-2002 in central Arizona (AZ) to evaluate effects of various N rates and fertigation frequencies on fruit yield and quality, leaf N concentration, and residual soil N of 'Newhall' navel oranges (Citrus sinensis) on 'Carrizo' citrange (Porcirus trifoliata x Citrus sinensis) rootstock (planted in 1997) grown in a Gilman (coarse-loamy, mixed, superactive, calcareous, hyperthermic Typic Torrifluvents) fine sandy loam. The experiment included nonfertilized control plots and factorial combinations of three fertigation frequencies (27, 9, and 3 applications annually) and three N rates (68, 136, and 204 g N tree-1 yr-1). Maximum yields occurred at N rates of 105 to 153 g N tree-1 yr-1 for the fourth to the sixth growing seasons. The yield-maximizing N rates were equivalent to 17 to 34% of currently recommended N rates for citrus grown in AZ. Fruit and juice quality did not show significant response to N rate or fertigation frequency. Leaf N concentrations at yield-maximizing N rates were above the critical leaf tissue N range of 25 to 27 mg g-1, indicating that this range may be too low for these 'Newhall' navel orange trees. During all three seasons, higher residual soil NO3 concentrations resulted from the highest N rate. Our results suggest that optimum N rates for microsprinkler-irrigated 'Newhall' navel oranges in AZ are lower than currently recommended N rates. © Soil Science Society of America.
• Wright, G. C., & Poe, S. E. (2005). 149) Arizona Farm Safety Day. Hortscience, 40(4), 1045-1045. doi:10.21273/hortsci.40.4.1045b
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  Arizona Farm Safety Day has been held annually since 2000 as an attempt to educate students and farm workers (pesticide applicators, tractor and equipment operators, irrigators, and field workers) in farm safety. Our programs have emphasized tractor safety, pesticide safety, ATV safety, electrical safety, and firearms safety. The all-day events have been held in Yuma and in Safford, Ariz., and most of the attendees are high school students. Agriculture students from six to eight high schools typically participate. The agenda is determined by consulting with local agriculture leaders. Attendees have the opportunity to attend a 4-hour training session in the morning. Subjects taught at these sessions might include reading a pesticide label, sprayer calibration, wearing proper protection, avoiding spray drift, tractor safety, and farm safety. At least one of these sessions is an outdoors “hands-on” session. Individual participants receive up-to-date information and literature, a certificate of completion, CEUs, CCA credits, a hat, and a lunch. Spanish translation is available at each session. In the afternoon, a tractor driver safety course and equipment demonstration is typically held. In the course, selected representatives from local farms or local youth get a chance to demonstrate their tractor and ATV driving and safety skills for recognition and awards. Plaques and trophies are awarded to the winners. Additionally, there is an equipment demonstration. Attendees are tested before and after the event.
• Wright, G. C., McCloskey, W. B., & Taylor, K. C. (2003). Managing orchard floor vegetation in flood-irrigated citrus groves. HortTechnology, 13(4), 668-677.
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  Abstract: Several orchard floor management strategies were evaluated beginning in Fall 1993 in a 'Limoneira 8A Lisbon' lemon (Citrus limon) grove on the Yuma Mesa in Yuma, Ariz. and in a 'Valencia' orange (Citrus sinensis) grove at the University of Arizona Citrus Agricultural Center, Waddell, Ariz. At Yuma, disking provided acceptable weed control except underneath the tree canopies where bermudagrass (Cynodon dactylon), purple nutsedge (Cyperus rotundus), and other weed species survived. Mowing the orchard floor suppressed broadleaf weed species allowing the spread of grasses, primarily bermudagrass. Preemergence (norflurazon and oryzalin) and postemergence (glyphosate and sethoxydim) herbicides were used to control weeds in the clean culture treatment in Yuma. After three harvest seasons (1994-95 through 1996-97), the cumulative yield of the clean culture treatment was 385 kg (848.8 lb) per tree, which was significantly greater than the 332 kg (731.9 lb) and 320 kg (705.5 lb) per tree harvested in the disking and mowing treatments, respectively. In addition, the clean culture treatment had a significantly greater percentage of fruit in the 115 and larger size category at the first harvest of the 1995-96 season than either the disk or mow treatments. At Waddell, the management strategies compared were clean culture (at this location only postemergence herbicides were used), mowing of resident weeds with a vegetation-free strip in the tree row, and a 'Salina' strawberry clover (Trifolium fragiferum) cover crop with a vegetation-free strip. The cumulative 3-year yield (1994-95 through 1996-97) of the clean culture treatment was 131 kg (288.8 lb) per tree, which was significantly greater then the 110 kg (242.5 lb) per tree yield of the mowed resident weed treatment. The yield of the strawberry clover treatment, 115 kg (253.5 lb) of oranges per tree, was not significantly different from the other two treatments. The presence of cover crops or weeds on the orchard floor was found to have beneficial effects on soil nitrogen and soil organic matter content, but no effect on orange leaf nutrient content. The decrease in yield in the disked or mowed resident weed treatments compared to the clean culture treatment in both locations was attributed to competition for water.
• Demetriou, M. C., Thompson, G. A., Wright, G. C., & Taylor, K. C. (2000). A molecular approach for the diagnosis of wood rotting disease in desert citrus. Mycologia, 92(1-6), 1214-1219.
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  Abstract: Brown heartwood rot is an increasingly important problem in southwestern deserts, affecting numerous native tree species, and commercial lemon production. Two fungal pathogens, Coniophora eremophila and Antrodia sinuosa, have been identified as causal agents of brown heartwood rot in citrus. Development of effective disease management strategies relies on the ability to readily identify and distinguish between the pathogens; therefore we have developed molecular markers as an alternative to morphometric methods to differentiate these two economically important pathogens. Random amplified polymorphic DNA analysis identified four primers that revealed fungal polymorphisms. Polymorphic DNA fragments were cloned, sequenced, and used to create a 700 bp sequence characterized amplified region (SCAR) in C. eremophila isolates using sequence-specific primers, Conio7 and Conio8. Three fragments (300, 650, and 1000 bp) were amplified with Conio7 and Conio8 in A. sinuosa isolates. A rapid, small scale method for DNA extraction from fungus was developed to expedite the technique. With this method, the usefulness of the Conio7 and Conio8 was verified using new Coniophora eremophila and Antrodia sinuosa isolates from citrus.
• Fidelibus, M. W., Martin, C. A., Wright, G. C., & Stutz, J. C. (2000). Effect of arbuscular mycorrhizal (AM) fungal communities on growth of 'Volkamer' lemon in continually moist or periodically dry soil. Scientia Horticulturae, 84(1-2), 127-140.
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  Abstract: Citrus volkameriana Tan. and Pasq. ('Volkamer' lemon) seedlings were inoculated with five different communities of arbuscular mycorrhizal (AM) fungi collected from citrus orchards in Mesa and Yuma, AZ, USA, and undisturbed North American Sonoran Desert and Chihuahuan Desert soils. Plants were then grown in a glasshouse for four months under continually moist or periodically dry conditions achieved by altering watering frequency so that before watering events container soil water tensions were approximately -0.01 MPa (continually moist) or -0.06 MPa (periodically dry) one half way down the container profile. Plants grown in continually moist soil had greater shoot growth than plants grown in periodically dry soil. Plant P status did not limit growth, and there was no interaction between watering frequency and AM fungal inoculum treatments. Plants inoculated with AM fungi from the Yuma orchard soil had significantly less root dry weight and total root length, and lower photosynthetic fluxes than plants treated with inoculum from the other soils. Specific soil respiration and an estimated carbon cost to benefit ratio were also higher for plants inoculated with AM fungi from the Yuma orchard soil than for plants treated with inoculum from the other soils. The Yuma orchard inoculum was distinctive in that > 80% of the total number of AM fungal spores were from a single species, Glomus occultum. These data showed that root growth suppression of plants treated with the Yuma inoculum, compared with plants treated with inoculum from all other sites, was substantial and greater in magnitude than the effect of periodic soil drying. Suppression of root growth might have resulted from increased AM fungal activity resulting in higher carbon costs to the plant. (C) 2000 Elsevier Science B.V.
• Wright, G. C. (1999). 237 Rootstock and Scion Trials for Lemon in Arizona. Hortscience, 34(3), 483-483. doi:10.21273/hortsci.34.3.483a
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  Five rootstocks, `Carrizo' citrange, Citrus macrophylla, Rough lemon, `Swingle' citrumelo, and Citrus volkameriana, were selected for evaluation using `Limoneira 8A Lisbon' as the scion. Four years of yield and fruit packout data indicate that trees on C. volkameriana and C. macrophylla are superior to those on other rootstocks in growth and yield. `Swingle' and `Carrizo' are performing poorly, and Rough lemon is intermediate. In a similar trial, four `Lisbon' lemon selections, `Frost Nucellar', `Corona Foothills', `Limoneira 8A', and `Prior' selections of Lisbon lemon were selected for evaluation on Citrus volkameriana rootstock. Four years of yield and packout data indicate that the `Limoneira 8A Lisbon' selection has generally outperformed the other selections in both growth and yield, although `Corona Foothills' has been superior in the 1998-99 harvest season.
• Wright, G. C. (1999). The carbohydrate economy of horticultural crops: Introduction to the colloquium. HortScience, 34(6), 1014-1015.
• Wright, G. C., Taylor, K. C., & Mccloskey, W. B. (1996). A Comparison of Four Orchard Floor Management Strategies for Lemons in Southwestern Arizona. Hortscience, 31(4), 578-578. doi:10.21273/hortsci.31.4.578b
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  Four orchard floor management strategies—disking, mowing, chemical mow, and clean culture using herbicides—were evaluated in a `Limoneira 8A Lisbon' lemon orchard in Southern Arizona, starting in the fall of 1993. Disking was the cultural practice used to manage the orchard floor before the start of the experiment. Although disking the orchard floor may have injured shallow tree roots, it provided satisfactory weed control except underneath the tree canopies where bermudagrass, purple nutsedge, and other weed species survived. Chemical mowing with Roundup at 1.168 L/ha did not provide satisfactory control of many weed species and required too many applications to be commercially feasible. This treatment was converted to a combination clean culture and disk treatment (clean and disk) in Summer 1995. Mowing the orchard suppressed broadleaf weed species, allowing the spread and establishment of grasses, primarily bermudagrass, and to a lesser extent, southern sandburr. A fall application of Solicam and Surflan followed by a summer spot treatment application of Roundup was used to control the weed flora in the clean culture treatment. Spot treatment applications of sethoxydim (Poast and Torpedo) were also made to control bermudagrass growing under the tree canopies in the clean culture treatment. Total 1995 yield of the mow, clean & disk, disk, and clean culture treatments were 4867, 5112, 5216, and 6042 kg of fruit, respectively. For the first harvest of 1995, the trees under clean culture also had significantly greater numbers of large fruit than did the trees under the other treatments.
• Wright, G. C., Patten, K. D., & Drew, M. C. (1995). Labeled sodium (22Na+) uptake and translocation in rabbiteye blueberry exposed to sodium chloride and supplemental calcium. Journal of the American Society for Horticultural Science, 120(2), 177-182.
• Wright, G. C., Patten, K. D., & Drew, M. C. (1994). Mineral composition of young rabbiteye and southern highbush blueberry exposed to salinity and supplemental calcium. Journal of the American Society for Horticultural Science, 119(2), 229-236.

Proceedings Publications

• Wright, G. C. (2018, March). The Date Industry in the United States and Mexico. In Sixth International Date Palm Conference, 117-122.
• Wright, G., & Kahn, T. (2012, Fall). Evaluation of Lemon Selections for the deserts of the United States. In Proc. Intl. Citrus Congress, 312.

Presentations

• Wright, G. C. (2018, March). The Date Industry in the United States and Mexico. Sixth International Date Palm Conference. Abu Dhabi, United Arab Emirates.
• Wright, G. C., & Schuch, U. K. (2015, October). Pomegranates - The Arizona Story. Florida Pomegranate Society Conference. Lake Alfred, FL: Florida Pomegranate Society.
• Wright, G. C. (2014, February). Manejo de huertos de mandarinas en ambientes desérticos. Citrica 2014, Lima Peru. Lima, Peru: Informaccion/Lima -Peru and UNALM - Universidad Nacional Agraria La Molina / Lima - Perú.
• Wright, G. C., Johnson, D., & El Houmaizi, M. A. (2014, March). Medjool- the King of Dates, and elite date cultivar. Fifth International Date Palm Congress, Abu Dhabi. Abu Dhabi, United Arab Emirates: UAE University.

Poster Presentations

• Piscatella, R., Thomas, Z., Wright, G. C., Kahn, T., Siebert-Wooldridge, T., Trunell, K., Federici, C. T., Roose, M., & Seymour, D. (2021, October). Leveraging Drones for Future Data Collection from Field Trials. California Citrus Conference. Visalia, CA: California Citrus Research Board.
  More info

  The manual collection of phenotypic data from field trials is physically demanding, time consuming, and expensive. Individuals must traverse field trials armed with measuring tapes, rulers, and their best judgment to measure and record data points by hand. Depending on the size of the field, these efforts often require multiple workers for hours if not days of labor. Manual measurements of tree performance are also prone to experimenter bias, especially for qualitative traits like scores of tree health. The emergence of camera-fitted drones allows us to automate this intensive process to reduce both time and resources required for data collection. First, we compare manual measurements of tree size to those captured by drones. We have collected both sets of data for two lemon field trials located in Riverside and Santa Paula, California. Automated measurements are highly correlated with manual measurements of tree and canopy size. Further testing and analysis will be performed to ensure that automated phenotyping using drones is a reliable substitute for manual measurements of tree size in field trials.
• Wright, G. C., Kahn, T., & Roose, M. (2021, October). Current Yield, Packout and Fruit Quality Results from Multilocation Lemon Scion Trials in California. California Citrus Conference. Visalia, CA: California Citrus Research Board.
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  We established multilocation (ML) lemon scion trials at four sites in Spring 2015. These locations include the LREC, a Limoneira-owned block near Santa Paula (SP), the UCR Agricultural Experiment Station (UCR), and the Coachella Valley Agricultural Research Station (CVARS), near Thermal. At each location, we planted 18 trees each of ‘Limoneira 8A Lisbon’ (L8A), ‘Limoneira 8A-IR1’ (IR1 - a low-seeded irradiated selection of ‘Limoneira 8A’), ‘Corona Foothills’(CFH), ‘Limonero Fino 49’(F49), ‘Walker Lisbon’ (WLK), and ‘Yen Ben’(YBN). Trees were budded to three rootstocks which varied by location. Yield data from LREC indicates that WLK has performed the best so far, while at SP, WLK and L8A have performed the best. At UCR, CFH, F49, L8A and WLK have performed well, while at CVARS, CFH and F49 are the best performers. Performance of IR1 varies depending on site and rootstock, while YBN performs poorly at all locations. There are scion by rootstock interactions at each site, but the best performers have cumulative yields of between 400 to 800 lbs. per tree regardless of site. CFH, F49 and occasionally IR1 typically have the largest fruit size, followed by L8A. and WLK. YBN has the smallest fruit. Again, there are interactions between scion and rootstock affecting fruit size at each site. Both IR1 and YBN have significantly fewer seeds than the other selections. Research supported by CRB project 5200-201
• Hoddle, M., & Wright, G. C. (2018, March). The South American Palm Weevil. Sixth International Date Palm Conference. Abu Dhabi, United Arab Emirates.
• Wright, G. C. (2017, August). Application of plant growth regulators and calcium to reduce skin separation in ‘Medjool’ dates. XIII International Symposium on Plant Bioregulators in Fruit Production. Chiba, Japan: International Society for Horticultural Science.
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  Summary: ‘Medjool’ is one of the world’s most expensive and profitable dates. However, costs to grow the fruit are also high, so the highest quality must be maintained. Exterior appearance is an important quality parameter. Skin separation (Figs. 1 and 2) is a defect that can downgrade the fruit and reduce profits. Skin separation occurs when the epicarp separates from the mesocarp; a phenomenon that appears only once the fruit dries to the rutab to the tamar stage, not in the khalal (colored) stage. Calcium, GA, and ABA have all been proposed to reduce skin separation. Applications of CaCl2(625 mg/l), S-ABA (500 ppm), CaCl2 (625 mg/l) + S-ABA (500 ppm), ProGibb® 40% at 24 g a.i., ProGibb® 40% at 32 g a.i., CalTrac (Ca fertilizer mfg. by Yara North America) at 4.7 l/ha and Powerbor CA (Calcium-boron fertilizer mfg. by Yara North America) at 4.7 l/ha were made to individual bunches of date fruit on 20 trees in two orchards in late July 2016. Two sequential harvests for each orchard occurred in September 2016, then the fruit was sorted by color, dehydrated to a uniform moisture content and resorted for quality. There was no consistent effect of treatments upon fruit color in the first harvests. However, applications of ProGibb led to significantly more fruit in the yellow khalal stage for the second harvests in both orchards. Applications of ABA, and sometimes ABA + CaCl2 led to a 5 to 10% increase in fruit of the higher quality, but these increases were trends, and were not significant. Subsequent experiments should take application timing into consideration.
• Wright, G. C., & Kahn, T. L. (2016, September). LEMON CULTIVAR EVALUATION FOR THE CALIFORNIA AND ARIZONA DESERTS. International Society of Citriculture Conference. Foz do Iguassu, Brazil: International Society of Citriculture.
• Wright, G. C., Matheron, M. E., & Martin, P. (2016, September). ANTRODIA SINUOSA – A WOOD ROTTING FUNGUS THAT ADVERSELY AFFECTS LEMONS IN ARIZONA. International Society of Citriculture Conference. Foz do Iguassu, Brazil: International Society of Citriculture.
• Wright, G. C., & Schuch, U. K. (2015, Aug). Pomegranate Variety Trial in Arizona. American Society for Horticultural Sciences Conference. New Orleans: American Society for Horticultural Sciences.
• Schuch, U. K., Wright, G. C., & Mahato, T. (2014, May 9). Pomegranate Variety Trial in Southern Arizona. Desert Horticulture Conference, Tucson. Tucson.
• Schuch, U. K., Wright, G. C., & Mahato, T. (2014, November 10). Pomegranate Variety Trial in Southern Arizona. CALS Annual Research Poster Forum, Tucson. Tucson.
• Wright, G. C. (2014, August). Mechanization and Innovation In The High-Value ‘Medjool’ Date Palm Orchard - Moving Into The Future. International Horticultural Congress, Brisbane. Brisbane, Australia: International Society for Horticultural Sciences.
• Wright, G. C., & Kahn, T. L. (2014, August). Evaluation of 12 Lemon Selections in The California Desert. International Horticultural Congress, Brisbane. Brisbane, Australia: International Society for Horticultural Sciences.
• Schuch, U. K., Wright, G. C., & Mahato, T. (2013, July). Pomegranate Variety Trial in Southern Arizona.. ASHS Annual Conference. Palm Desert, CA: American Society for Horticultural Sciences.

Others

• Begeman, J., & Wright, G. C. (2024, February). Diagnosticando problemas de los cítricos de casa. Arizona Cooperative Extension Publication AZ1492S-2024.
  More info

  https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1492S-2024.pdf
• Wright, G. C. (2022, June). Tabla de fertilización de cítricos en Arizona. Arizona Cooperative Extension Publication AZ1671S-2022. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1671S-2022.pdf
• Wright, G. C. (2022, May). Citrus Rootstock Acquisition and Evaluation - 2020/2021. Arizona Citrus Research Council Website. https://agriculture.az.gov/arizona-citrus-research-council-previously-funded-research-projects
• Wright, G. C. (2021, June). Grapefruit and Pummelo for Southern Arizona. Arizona Cooperative Extension Publication AZ1925-2021. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1925-2021.pdf
• Wright, G. C. (2021, May). Citrus Rootstock Acquisition and Evaluation - 2019. Arizona Citrus Research Council Website. https://agriculture.az.gov/arizona-citrus-research-council-previously-funded-research-projects
• Wright, G. C. (2021, May). Irrigating Citrus Trees. Arizona Cooperative Extension Publication AZ1151-2021. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1151-2021.pdf
• Wright, G. C. (2020, JUly). Cómo regar los cítricos. Arizona Cooperative Extension Publication AZ1151S-2020. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1151S-2020.pdf
• Wright, G. C. (2020, September). Oranges for Southern Arizona. Arizona Cooperative Extension Publication AZ1850-2020. https://extension.arizona.edu/pubs/oranges-southern-arizona
• Hu, J., & Wright, G. C. (2019, July). Coupling Spore Traps and Quantitative PCR Assays for Detection and Quantification of Airborne Spores of Antrodia sinuosa in Lemon Orchards of Yuma - 2018. Arizona Citrus Research Council Website https://agriculture.az.gov/arizona-citrus-research-council-previously-funded-research-projects. https://agriculture.az.gov/sites/default/files/documents/Coupling%20Spore%20Traps%20and%20Quantitative%20PCR%20Assays%20for%20Detection%20and%20Quantification%20of.......%20-%202018.pdf
• Hu, J., & Wright, G. C. (2019, June). Huanglongbing of Citrus. University of Arizona Cooperative Extension Publication AZ 1795. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1795-2019.pdf
• Wright, G. C., & Poe, S. E. (2019, July). Citrus Rootstock Acquisition and Evaluation — 2018. Arizona Citrus Research Council Website https://agriculture.az.gov/arizona-citrus-research-council-previously-funded-research-projects. https://agriculture.az.gov/sites/default/files/documents/Citrus%20Rootstock%20Acquisition%20and%20Evaluation%20%20-%202018.pdf
• Wright, G. C. (2018, March). Control of Brown Wood Rot in Lemons - 2017. Arizona Citrus Research Council Website.
  More info

  file:///C:/Users/Glenn%20Wright/Downloads/Control%20of%20brown%20wood%20rot%20in%20lemons%20-%202017.pdf
• Wright, G. C., & Poe, S. E. (2018, March). Citrus Rootstock Acquisition and Evaluation — 2017. Arizona Citrus Research Council Website.
  More info

  file:///C:/Users/Glenn%20Wright/Downloads/Citrus%20Rootstock%20Acquisition%20and%20Evaluation%20New%20%20%202017.pdf
• Wright, G. C. (2015, February). Area-Wide Spraying for Asian Citrus Psyllid in Texas and Florida. Commodity Research Report. http://extension.arizona.edu/pubs/area-wide-spraying-asian-citrus-psyllid-texas-and-florida
  More info

  Realizing that the Arizona citrus industry might someday have to deal with widespread ACP control, the Arizona Citrus Research Council approved a trip to Florida and Texas to investigate how ACP control was accomplished in those two states. The trips were to McAllen, Texas on 9-12 Nov 2011 and to Immokalee Florida on 17-18 Nov. 2011. In McAllen, I interviewed Dr. Mamoudou Setamou, extension entomologist for Texas A&M – Kingsville and his staff, and Mr. Ray Prewitt, president of Texas Citrus Mutual. In Florida, I interviewed Mr. Ron Hamel, manager of the Gulf Citrus Growers, and Dr. Mongi Zekri, southwest Florida Multi-County Citrus Agent, housed at the Hendry County Extension Office in LaBelle., FL. The author hopes that some of this information can be used in the development of an Area Wide Spray Plan in Arizona.
• Wright, G. C. (2015, February). Control of Brown Wood Rot in Lemons with Low Pressure Injection 2012. Commodity Research Report. http://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1652-2015.pdf
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  Abstract We injected AGRA PHOS (Potassium Phosphite) 0-2.4-2, Propaconizole – 0.05%, Propaconizole plus Azoxystrobin – 0.117 and 0.135% respectively, Zn, Mn and Fe 0.105, 0.112, and 0.10% respectively, and Azoxystrobin – 0.137% using a low pressure injection system for the control of Antrodia sinuosa in lemon trees. The Propaconizole + Azoxystrobin treatment, the Azoxystrobin treatment, and the Zn + Mn + Fe treatment led to significantly less fungal lesion growth when applied prior to the introduction of the fungus, as compared to their application after fungal introduction.
• Wright, G. C. (2015, February). Evaluation of Nitrogen Fertilization Practices for Surface-Irrigated Lemon Trees – 2012. Commodity Research Report. http://extension.arizona.edu/pubs/evaluation-nitrogen-fertilization-practices-surface-irrigated-lemon-trees-2012
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  Abstract: Lisbon lemons were treated with N levels ranging from 0.5 to 3.0 lbs. N per tree annually. Fourth–season yield results from the trial show significant effects of the treatments upon overall yield and leaf N concentrations, but no effect upon fruit packout. Treatments did lead to a significant effect upon leaf nutrient concentration. Total cumulative yields from 2008 to 2012 (not including the freeze-affected 2011-12 season) were significantly affected by the treatments. Trees treated annually with 2.0 lbs N had the greatest yield, which represented a 12% increase over the yield of trees treated with just 0.5 lbs. N annually.
• Wright, G. C. (2015, July). Citrus Fertilization Chart for Arizona. CALS Extension Publication #AZ1671. http://extension.arizona.edu/pubs/citrus-fertilization-chart-arizona
• Wright, G. C. (2015, September). Control of Brown Wood Rot in Lemons with Low Pressure Injection 2013-14. Commodity Research Report. http://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1680-2015.pdf