Scholarly Works, Virginia Agricultural Experiment Station

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https://hdl.handle.net/10919/24309

VAES faculty are located at 11 Agricultural Research and Extension Centers in Virginia and three colleges at Virginia Tech (CALS, CNRE, and VMRCVM).

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Evaluation of Giant Knotweed Extract, Regalia, and Antibiotics in Control of Shoot Blight and Fire Blight Canker Phases on Apple
Boeckman, Nathanial; Borba, Matheus Correa; Aćimović, Srđan G. (MDPI, 2024-09-26)
We evaluated the effectiveness of three different treatment groups at managing apple shoot blight, and the resulting canker incidence and canker length on wood caused by Erwinia amylovora. Preventative foliar sprays or trunk injections of giant knotweed extract (Regalia), oxytetracycline (Arbor-OTC or FireLine + Regulaid), or streptomycin (Agri-mycin/FireWall + Regulaid) were applied to mature ‘Fuji’ trees. Regalia and oxytetracycline were ineffective at reducing shoot blight severity, showing poor disease reductions of 18.2% and 24.3% compared to untreated controls across both years. Streptomycin was effective at controlling shoot blight severity when applied as a spray application, reducing necrosis by up to 93.9% across both years. Canker incidence was also poorly reduced by Regalia and oxytetracycline with an average decrease of 33.3% and 52.4%, respectively. Again, spray applications of streptomycin were most effective at reducing canker incidence (95.2%). When present, canker length was best controlled by spray applications of streptomycin, showing an average reduction of 95.7%. The effectiveness of Regalia and oxytetracycline was poor, reducing canker length by only 30.4% and 43.5%, respectively. Trunk injections of Regalia were consistently less effective than spray applications. Compared to their spray application counterpart, Regalia injections were, on average, 12.5%, 26.3%, and 25.1% less effective at reducing shoot blight severity, canker incidence, and canker length, respectively. Injected Arbor-OTC was more effective than spray applications of oxytetracycline. On average, Arbor-OTC injections were up to 28.3%, 40.1%, and 30% more effective at reducing shoot blight severity, canker incidence, and canker length compared to spray applications. Overall, Regalia and oxytetracycline were not as effective as streptomycin at controlling fire blight. The search for organic antibiotic alternatives for shoot blight and canker control continues, as cankers are increasing in economic importance by causing bearing wood and young tree death.
Seafood Purchasing Behavior in the U.S. during the Early Recovery Period from the COVID-19 Pandemic
Uzmanoglu, Mustafa Selcuk; Hegde, Shraddha; Engle, Carole; van Senten, Jonathan; Kumar, Ganesh; Dey, Madan (MDPI, 2024-09-03)
This study examined seafood consumption during the early period of economic recovery following the COVID-19 pandemic. Specifically, surveys of U.S. consumers compared seafood purchasing behavior of the first two quarters of 2021 (Q1, 1 January through 31 March 2021, and Q2, 1 April through 30 June 2021) with those of 2020. Each survey included 100 seafood consumer respondents in each of the 20 U.S. metropolitan market areas. Following data cleaning, there were 1885 valid responses for Q1-2021 and 1940 for Q2-2021. A majority (57%) of respondents had received at least one dose of the COVID-19 vaccine before March 2021 and 70% had received at least one dose as of June 2021. Regardless of vaccination status, few respondents (6% to 9.5% for food generally and 4% to 6.5% for seafood) reported changes in seafood consumption. Seafood consumption away from home increased significantly in Q1-2021 as compared to 2020 and continued to increase but to a lesser degree in Q2-2021. Demographic differences were found in shopping behaviors by age, education, income, and gender, but not by ethnic group. Generally, higher-income females with higher education tended to purchase more seafood. Respondents reported increased numbers of shopping trips per year in Q1-2021 as compared to 2020, which continued into Q2-2021 for general food, but shopping trips for seafood decreased as compared to 2020. The frequency of takeout purchases (times/year) of prepared meals for home consumption of seafood decreased during Q1 from 2020 and remained at that level in Q2-2021, but home delivery purchases of prepared meals of seafood increased during this period. Approximately 50–55% of respondents reported no change in overall seafood consumption levels, while 28% noted an increase in seafood consumption compared to pre-pandemic periods, a significant increase from the 19% who had reported doing so pre-pandemic. In contrast, those reporting a decrease declined from 31% to 17% in comparison to pre-pandemic levels. Seafood consumption in the U.S. remained stable and recovered in early 2021, with a preference for dining out. Consumer behaviors varied by age, income, education, and gender, but not by ethnicity. These changes were primarily driven by access, availability, and income, indicating the need for further research on long-term consumption patterns. This study found apparent stability of seafood consumption by U.S. consumers, which recovered from pandemic consumption levels in early 2021, and there was little change in seafood consumption, frequency, or the types of seafood consumed. Vaccination status did not appear to affect seafood consumption.
Evaluation of 1021Bp, a close relative of Pseudomonas eucalypticola, for potential of plant growth promotion, fungal pathogen suppression and boxwood blight control
Kong, Ping; Hong, Chuanxue (2024-09-14)
Background: Pseudomonas eucalypticola, a new species of the P. fluorescens group that generates most Pseudomonas-based biocontrol agents, has not been found in any plants other than Eucalyptus dunnii leaves. Except for antagonism to the growth of a few fungi, its features in plant growth promotion and disease control have not been evaluated. Here, we identified a similar species of P. eucalypticola, 1021Bp, from endophyte cultures of healthy leaves of English boxwood (Buxus sempervirens ‘Suffruticosa’) and investigated its antifungal activity, plant growth promotion traits, and potential for boxwood blight control. Results: Colorimetric or plate assays showed the properties of 1021Bp in nitrogen fixation, phosphate solubilization, and production of indole-3-acetic acid (IAA) and siderophores, as well as the growth suppression of all five plant fungal pathogens, including causal agents of widespread plant diseases, gray mold, and anthracnose. Boxwood plant leaves received 87.4% and 65.8% protection from infection when sprayed with cell-free cultural supernatant (CFS) but not the resuspended bacterial cells at 108–9/mL of 1021Bp at one and seven days before inoculation (dbi) with boxwood blight pathogen, Calonectria pseudonaviculata, at 5 × 104 spores/mL. They also received similarly high protection with the 1021Bp cell culture without separation of cells and CFS at 14 dbi (67.5%), suggesting a key role of 1021Bp metabolites in disease control. Conclusions: Given the features of plant growth and health and its similarity to P. eucalypticola with the P. fluorescens lineage, 1021Bp has great potential to be developed as a safe and environmentally friendly biofungicide and biofertilizer. However, its metabolites are the major contributors to 1021Bp activity for plant growth and health. Application with the bacterial cells alone, especially with nonionic surfactants, may result in poor performance unless survival conditions are present.
Virginia Tech Shenandoah Valley Agricultural Research and Extension Center McCormick Farm 2024 Field Day Proceedings
Pent, Gabriel J. (Virginia Tech, 2024-08-07)
The Shenandoah Valley AREC holds biennial field days to allow agricultural producers the opportunity to learn more about the research being conducted at the Center and interact with faculty conducting the research.
Silvopastures: Benefits, Past Efforts, Challenges, and Future Prospects in the United States
Poudel, Sanjok; Pent, Gabriel J.; Fike, John H. (MDPI, 2024-06-26)
The global human population is projected to reach 9.7 billion by 2050, increasing the demand for food and fiber, but also raising concerns about the environmental impact of agricultural production scaled to meet their needs. Silvopastures—integrated tree–forage–livestock systems—have emerged as a viable practice to meet the required productivity and environmental stewardship outcomes. This review consolidates the extensive research on silvopasture practices in the United States and highlights the benefits of these systems. A comprehensive literature search across databases such as ScienceDirect and Google Scholar revealed 152 publications on silvopastures in the United States since 2000, indicating growing interest. These studies have primarily focused on the impacts of silvopastures on livestock welfare and productivity, forage production and composition, soil health and nutrient dynamics, and socio-economic factors. Geographical distribution analysis indicated that the research is more focused in the Southeastern United States, with Florida, Virginia, Alabama, Missouri, and Arkansas being the top five contributing states. The review also offers insights into the tree and forage species used across these states and discusses the challenges to silvopasture adoption among producers and land managers while exploring future prospects. This review may be used as a resource for understanding the multifaceted dimensions of silvopasture adoption, providing insights for researchers, policymakers, and practitioners alike.
Unveiling the Arsenal of Apple Bitter Rot Fungi: Comparative Genomics Identifies Candidate Effectors, CAZymes, and Biosynthetic Gene Clusters in Colletotrichum Species
Khodadadi, Fatemeh; Luciano-Rosario, Dianiris; Gottschalk, Christopher; Jurick, Wayne M.; Aćimović, Srđan G. (MDPI, 2024-07-16)
The bitter rot of apple is caused by Colletotrichum spp. and is a serious pre-harvest disease that can manifest in postharvest losses on harvested fruit. In this study, we obtained genome sequences from four different species, C. chrysophilum, C. noveboracense, C. nupharicola, and C. fioriniae, that infect apple and cause diseases on other fruits, vegetables, and flowers. Our genomic data were obtained from isolates/species that have not yet been sequenced and represent geographic-specific regions. Genome sequencing allowed for the construction of phylogenetic trees, which corroborated the overall concordance observed in prior MLST studies. Bioinformatic pipelines were used to discover CAZyme, effector, and secondary metabolic (SM) gene clusters in all nine Colletotrichum isolates. We found redundancy and a high level of similarity across species regarding CAZyme classes and predicted cytoplastic and apoplastic effectors. SM gene clusters displayed the most diversity in type and the most common cluster was one that encodes genes involved in the production of alternapyrone. Our study provides a solid platform to identify targets for functional studies that underpin pathogenicity, virulence, and/or quiescence that can be targeted for the development of new control strategies. With these new genomics resources, exploration via omics-based technologies using these isolates will help ascertain the biological underpinnings of their widespread success and observed geographic dominance in specific areas throughout the country.
Impact Assessment of Nematode Infestation on Soybean Crop Production Using Aerial Multispectral Imagery and Machine Learning
Jjagwe, Pius; Chandel, Abhilash K.; Langston, David B. (MDPI, 2024-06-24)
Accurate and prompt estimation of geospatial soybean yield (SY) is critical for the producers to determine key factors influencing crop growth for improved precision management decisions. This study aims to quantify the impacts of soybean cyst nematode (SCN) infestation on soybean production and the yield of susceptible and resistant seed varieties. Susceptible varieties showed lower yield and crop vigor recovery, and high SCN population (20 to 1080) compared to resistant varieties (SCN populations: 0 to 340). High-resolution (1.3 cm/pixel) aerial multispectral imagery showed the blue band reflectance (r = 0.58) and Green Normalized Difference Vegetation Index (GNDVI, r = −0.6) have the best correlation with the SCN populations. While GDNVI, Green Chlorophyll Index (GCI), and Normalized Difference Red Edge Index (NDRE) were the best differentiators of plant vigor and had the highest correlation with SY (r = 0.59–0.75). Reflectance (REF) and VIs were then used for SY estimation using two statistical and four machine learning (ML) models at 10 different train–test data split ratios (50:50–95:5). The ML models and train–test data split ratio had significant impacts on SY estimation accuracy. Random forest (RF) was the best and consistently performing model (r: 0.84–0.97, rRMSE: 8.72–20%), while a higher train–test split ratio lowered the performances of the ML models. The 95:5 train–test ratio showed the best performance across all the models, which may be a suitable ratio for modeling over smaller or medium-sized datasets. Such insights derived using high spatial resolution data can be utilized to implement precision crop protective operations for enhanced soybean yield and productivity.
Thermal-RGB Imagery and Computer Vision for Water Stress Identification of Okra (Abelmoschus esculentus L.)
Rajwade, Yogesh A.; Chandel, Narendra S.; Chandel, Abhilash K.; Singh, Satish Kumar; Dubey, Kumkum; Subeesh, A.; Chaudhary, V. P.; Ramanna Rao, K. V.; Manjhi, Monika (MDPI, 2024-06-27)
Crop canopy temperature has proven beneficial for qualitative and quantitative assessment of plants' biotic and abiotic stresses. In this two-year study, water stress identification in okra crops was evaluated using thermal-RGB imaging and AI approaches. Experimental trials were developed for two irrigation types, sprinkler and flood, and four deficit treatment levels (100, 50, 75, and 25% crop evapotranspiration), replicated thrice. A total of 3200 thermal and RGB images acquired from different crop stages were processed using convolutional neural network architecture-based deep learning models (1) ResNet-50 and (2) MobileNetV2. On evaluation, the accuracy of water stress identification was higher with thermal imagery inputs (87.9% and 84.3%) compared to RGB imagery (78.6% and 74.1%) with ResNet-50 and MobileNetV2 models, respectively. In addition, irrigation treatment and levels had significant impact on yield and crop water use efficiency; the maximum yield of 10,666 kg ha⁻¹ and crop water use efficiency of 1.16 kg m⁻³ was recorded for flood irrigation, while 9876 kg ha⁻¹ and 1.24 kg m⁻³ were observed for sprinkler irrigation at 100% irrigation level. Developments and observations from this study not only suggest applications of thermal-RGB imagery with AI for water stress quantification but also developing and deploying automated irrigation systems for higher crop water use efficiency.
Valorization of Seafood Waste for Food Packaging Development
Zhan, Zhijing; Feng, Yiming; Zhao, Jikai; Qiao, Mingyu; Jin, Qing (MDPI, 2024-07-03)
Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.
Assessing Economic Contributions of the Virginia Seafood Industry: An Estimation Framework Utilizing Primary Data
Gonçalves, Fernando H.; van Senten, Jonathan; Schwarz, Michael H.; Hegde, Shraddha (MDPI, 2024-05-26)
With a focus on seafood industries, this study provides a framework for economic contribution assessments, outlines Virginia’s seafood supply chain components, and evaluates the direct, indirect, and induced economic impacts of Virginia’s seafood industry in 2019. Utilizing an analysis-by-parts method in IMPLAN, primary expenditure data from watermen, aquaculture farmers, processors, and distributors were collected through surveys. The efficacy of obtaining primary data through stakeholder surveys heavily relies on the investigator’s interpersonal skills to establish trust and elucidate the study’s benefits, particularly its potential to inform policy decisions. In 2019, the Virginia seafood industry’s estimated total economic contributions amounted to USD 1.1 billion, supporting 7187 individuals. This impact encompasses 6050 direct jobs, 523 indirect jobs, and 614 induced jobs, primarily benefiting watermen and coastal communities. Furthermore, the industry’s influence extends beyond its immediate economic sphere, supporting diverse sectors such as polystyrene foam manufacturing, boat building, sporting and athletic goods, and commercial and industrial machinery. Wages and salaries disbursed throughout the seafood supply chain ripple to Virginia’s economy, benefiting nondepository credit intermediation, owner-occupied dwellings, and real estate sectors. Future research focusing on seafood sales in restaurants and retail outlets will complete the understanding of the seafood industry’s broader economic impact on the state.
Phenotypic Dissection of Drought Tolerance in Virginia and Carolinas within a Recombinant Inbred Line Population Involving a Spanish and a Virginia-Type Peanut Lines
Kumar, Naveen; Haak, David C.; Dunne, Jeffrey C.; Balota, Maria (MDPI, 2024-06-08)
Peanut (Arachis hypogaea L.) is a rainfed crop grown in both tropical and subtropical agro-climatic regions of the world where drought causes around 20% yield losses per year. In the United States, annual losses caused by drought are around $50 million. The objective of this research was to (1) identify genetic variation for the normalized difference vegetation index (NDVI), canopy temperature depression (CTD), relative chlorophyll content by SPAD reading (SCMR), CO₂ assimilation rate, and wilting among recombinant inbred lines (RILs) derived from two diverse parents N08086olJCT and ICGV 86015, to (2) determine if the physiological traits can be used for expediting selection for drought tolerance, and (3) experimental validation to identify lines with improved yield under water-limited conditions. Initially, 337 lines were phenotyped under rainfed production and a selected subset of 52 RILs were tested under rainout shelters, where drought was imposed for eight weeks during the midseason (July and August). We found that under induced drought, pod yield was negatively correlated with wilting and CTD, i.e., cooler canopy and high yield correlated positively with the NDVI and SPAD. These traits could be used to select genotypes with high yields under drought stress. RILs #73, #56, #60, and #31 performed better in terms of yield under both irrigated and drought conditions compared to check varieties Bailey, a popular high-yielding commercial cultivar, and GP-NC WS 17, a drought-tolerant germplasm.
Comparing Regression and Classification Models to Estimate Leaf Spot Disease in Peanut (Arachis hypogaea L.) for Implementation in Breeding Selection
Chapu, Ivan; Chandel, Abhilash; Sie, Emmanuel Kofi; Okello, David Kalule; Oteng-Frimpong, Richard; Okello, Robert Cyrus Ongom; Hoisington, David; Balota, Maria (MDPI, 2024-04-30)
Late leaf spot (LLS) is an important disease of peanut, causing global yield losses. Developing resistant varieties through breeding is crucial for yield stability, especially for smallholder farmers. However, traditional phenotyping methods used for resistance selection are laborious and subjective. Remote sensing offers an accurate, objective, and efficient alternative for phenotyping for resistance. The objectives of this study were to compare between regression and classification for breeding, and to identify the best models and indices to be used for selection. We evaluated 223 genotypes in three environments: Serere in 2020, and Nakabango and Nyankpala in 2021. Phenotypic data were collected using visual scores and two handheld sensors: a red–green–blue (RGB) camera and GreenSeeker. RGB indices derived from the images, along with the normalized difference vegetation index (NDVI), were used to model LLS resistance using statistical and machine learning methods. Both regression and classification methods were also evaluated for selection. Random Forest (RF), the artificial neural network (ANN), and k-nearest neighbors (KNNs) were the top-performing algorithms for both regression and classification. The ANN (R²: 0.81, RMSE: 22%) was the best regression algorithm, while the RF was the best classification algorithm for both binary (90%) and multiclass (78% and 73% accuracy) classification. The classification accuracy of the models decreased with the increase in classification classes. NDVI, crop senescence index (CSI), hue, and greenness index were strongly associated with LLS and useful for selection. Our study demonstrates that the integration of remote sensing and machine learning can enhance selection for LLS-resistant genotypes, aiding plant breeders in managing large populations effectively.
Evaluation of Production and Pest Management Practices in Peanut (Arachis hypogaea) in Ghana
Seidu, Ahmed; Abudulai, Mumuni; Dzomeku, Israel K.; Mahama, Georgie Y.; Nboyine, Jerry A.; Appaw, William; Akromah, Richard; Arthur, Stephen; Bolfrey-Arku, Grace; Mochiah, M. Brandford; Jordan, David L.; Brandenburg, Rick L.; MacDonald, Greg; Balota, Maria; Hoisington, David; Rhoads, Jamie (MDPI, 2024-05-06)
The economic return for peanut (Arachis hypogaea L.) in Ghana is often low due to limitations in the availability of inputs or their adoption, which are needed to optimize yield. Six experiments were conducted in Ghana in 2020 and 2021 to determine the impact of planting date, cultivar, fertilization, pest management practices, and harvest date on peanut yield, financial return, and pest reaction. A wide range of interactions among these treatment factors were often observed for infestations of aphids (Aphis gossypii Glover); groundnut rosette disease (Umbravirus: Tombusviridaee); millipedes (Peridontopyge spp.); white grubs (Schyzonicha spp.); wireworms (Conoderus spp.); termites (Microtermes and Odontotermes spp.); canopy defoliation as a result of early leaf spot disease caused by Passalora arachidicola (Hori) and late leaf spot caused by Nothopassalora personata (Berk. and M. A. Curtis); and the scarification and boring of pods caused by arthropod feeding. Pod yield and economic return increased for the cultivar Chitaochi and Sarinut 2 when fertilizer was applied and when fertilizer was applied at early, mid-, and late planting dates. Pod yield and economic return increased when a combination of locally derived potassium soaps was used for aphid suppression and one additional hand weeding was used in the improved pest management practice compared with the traditional practice without these inputs. Pearson correlations for yield and economic return were negatively correlated for all pests and damage caused by pests. The results from these experiments can be used by farmers and their advisors to develop production packages for peanut production in Ghana.
New Species-Specific Real-Time PCR Assays for Colletotrichum Species Causing Bitter Rot of Apple
McHenry, Diana J.; Aćimović, Srđan G. (MDPI, 2024-04-27)
Bitter rot of apple is an economically important worldwide disease caused by different Colletotrichum species, depending on many factors such as climate, geography, other hosts, and crop management practices. Culture, morphology, and single-locus sequencing-based methods for identifying the Colletotrichum species are severely limited in effectiveness, while the multilocus sequence typing methods available for delineating species are costly, time-intensive, and require high expertise. We developed species-specific hydrolysis probe real-time PCR assays for the following nine Colletotrichum species causing bitter rot in the Mid-Atlantic U.S.A.: C. fructicola, C. chrysophilum, C. noveboracense, C. gloeosporioides s.s., C. henanense, C. siamense and C. theobromicola from the C. gloeosporioides species complex, and C. fioriniae and C. nymphaeae from the C. acutatum species complex. After searching 14 gene regions, we designed primers and probes in 5 of them for the nine target species. Four primer–probe set pairs were able to be duplexed. Sensitivity tests showed as little as 0.5 pg DNA were detectable. These real-time PCR assays will provide rapid and reliable identification of these key Colletotrichum species and will be critically important for studies aiming to elucidate their biology, epidemiology, and management on apples as the number one produced and consumed tree fruit in the U.S.A.
Evaluating Different Methods to Establish Biodiverse Swards of Native Grasses and Wildflowers for Pasturelands
Kubesch, Jonathan O. C.; Greiner, Scott P.; Pent, Gabriel J.; Reid, J. Leighton; Tracy, Benjamin F. (MDPI, 2024-05-14)
Many cool-season pastures in the southeastern U.S. are dominated by a competitive cool-season grass, tall fescue (Schedonorus arundinaceus), and lack substantial plant diversity. Planting native warm-season grasses (NWSGs) and wildflowers (WFs) into these pastures could provide summer forage for cattle and more floral resources for pollinators. This paper summarizes field experiments designed to evaluate different spatiotemporal planting arrangements of NWSGs and WFs to improve their establishment success. The study was conducted from April 2021 to October 2023 in central Virginia (USA). Planting treatments included NWSG and WF mixtures planted: (1) together in the same space, (2) spatially separated in space (i.e., side by side), or (3) temporally separated where NWSGs and WFs were planted in difference sequences. Results showed few differences in forage mass, floral production, and botanical composition as well as stand density in 2021 and 2022. In 2023, NWSG abundance was greater where grasses were planted first or mixed with WFs. Similarly, the WF component was favored when they were planted before NWSGs. Overall, planting NWSG and WF mixes separately, either spatially or temporally, favors successful establishment and could offer more flexibility for using selective herbicides to suppress the heavy weed pressure that often accompanies these plantings.
Phenotyping Peanut Drought Stress with Aerial Remote-Sensing and Crop Index Data
Balota, Maria; Sarkar, Sayantan; Bennett, Rebecca S.; Burow, Mark D. (MDPI, 2024-04-02)
Peanut (Arachis hypogaea L.) plants respond to drought stress through changes in morpho-physiological and agronomic characteristics that breeders can use to improve the drought tolerance of this crop. Although agronomic traits, such as plant height, lateral growth, and yield, are easily measured, they may have low heritability due to environmental dependencies, including the soil type and rainfall distribution. Morpho-physiological characteristics, which may have high heritability, allow for optimal genetic gain. However, they are challenging to measure accurately at the field scale, hindering the confident selection of drought-tolerant genotypes. To this end, aerial imagery collected from unmanned aerial vehicles (UAVs) may provide confident phenotyping of drought tolerance. We selected a subset of 28 accessions from the U.S. peanut mini-core germplasm collection for in-depth evaluation under well-watered (rainfed) and water-restricted conditions in 2018 and 2019. We measured morpho-physiological and agronomic characteristics manually and estimated them from aerially collected vegetation indices. The peanut genotype and water regime significantly (p < 0.05) affected all the plant characteristics (RCC, SLA, yield, etc.). Manual and aerial measurements correlated with r values ranging from 0.02 to 0.94 (p < 0.05), but aerially estimated traits had a higher broad sense heritability (H²) than manual measurements. In particular, CO₂ assimilation, stomatal conductance, and transpiration rates were efficiently estimated (R² ranging from 0.76 to 0.86) from the vegetation indices, indicating that UAVs can be used to phenotype drought tolerance for genetic gains in peanut plants.
Lasiodiplodia iraniensis and Diaporthe spp. Are Associated with Twig Dieback and Fruit Stem-End Rot of Sweet Orange, Citrus sinensis, in Florida
Piattino, Valeria; Aiello, Dalia; Dardani, Greta; Martino, Ilaria; Flores, Mauricio; Aćimović, Srđan G.; Spadaro, Davide; Polizzi, Giancarlo; Guarnaccia, Vladimiro (MDPI, 2024-04-17)
Florida ranks among the most important citrus growing regions in the USA. The present study investigates the occurrence, diversity, and pathogenicity of fungal species associated with symptomatic sweet orange (Citrus sinensis) cv. Valencia plants and fruit. The survey was conducted on twigs and fruit collected in Southwest Florida during 2022. Based on morphological and molecular characteristics, the identified isolates belonged to the species Lasiodiplodia iraniensis, Diaporthe pseudomangiferae, and Diaporthe ueckerae. The pathogenicity of representative isolates was evaluated on citrus fruit and plants. Lasiodiplodia iraniensis was the most virulent on fruit and plants, followed by Diaporthe pseudomangiferae. Diaporthe ueckerae had the lowest virulence on fruit, and it was not pathogenic to plants. In vitro tests were performed to assess the effect of temperature on mycelial radial growth. The optimum temperature of growth ranged from 26.0 to 28.4 °C for all the evaluated species, and L. iraniensis showed the fastest mycelial growth. This study represents the first report of L. iraniensis as a causal agent of tree dieback and fruit stem-end rot on C. sinensis worldwide. Moreover, D. pseudomangiferae and D. ueckerae are reported here for the first time in association with citrus diseases worldwide.
Transcriptome Profiling of a Salt Excluder Hybrid Grapevine Rootstock ‘Ruggeri’ throughout Salinity
Gajjar, Pranavkumar; Ismail, Ahmed; Islam, Tabibul; Moniruzzaman, Md; Darwish, Ahmed G.; Dawood, Ahmed S.; Mohamed, Ahmed G.; Haikal, Amr M.; El-Saady, Abdelkareem M.; El-Kereamy, Ashraf; Sherif, Sherif M.; Abazinge, Michael D.; Kambiranda, Devaiah; El-Sharkawy, Islam (MDPI, 2024-03-14)
Salinity is one of the substantial threats to plant productivity and could be escorted by other stresses such as heat and drought. It impairs critical biological processes, such as photosynthesis, energy, and water/nutrient acquisition, ultimately leading to cell death when stress intensity becomes uncured. Therefore, plants deploy several proper processes to overcome such hostile circumstances. Grapevine is one of the most important crops worldwide that is relatively salt-tolerant and preferentially cultivated in hot and semi-arid areas. One of the most applicable strategies for sustainable viticulture is using salt-tolerant rootstock such as Ruggeri (RUG). The rootstock showed efficient capacity of photosynthesis, ROS detoxification, and carbohydrate accumulation under salinity. The current study utilized the transcriptome profiling approach to identify the molecular events of RUG throughout a regime of salt stress followed by a recovery procedure. The data showed progressive changes in the transcriptome profiling throughout salinity, underpinning the involvement of a large number of genes in transcriptional reprogramming during stress. Our results established a considerable enrichment of the biological process GO-terms related to salinity adaptation, such as signaling, hormones, photosynthesis, carbohydrates, and ROS homeostasis. Among the battery of molecular/cellular responses launched upon salinity, ROS homeostasis plays the central role of salt adaptation.
Effects of Grosmannia clavigera and Leptographium longiclavatum on Western White Pine Seedlings and the Fungicidal Activity of Alamo®, Arbotect®, and TREE-äge®
Wyka, Stephen A.; Doccola, Joseph J.; Strom, Brian L.; Smith, Sheri L.; McPherson, Douglas W.; Aćimović, Srđan G.; Klepzig, Kier D. (International Society of Arboriculture, 2016-03-15)
Bark beetles carry a number of associated organisms that are transferred to the host tree upon attack that are thought to play a role in tree decline. To assess the pathogenicity to western white pine (WWP; Pinus monticola) of fungi carried by the mountain pine beetle (MPB; Dendroctonus ponderosae), and to evaluate the potential for systemic prophylactic treatments for reducing fungal impacts, experiments were conducted with WWP seedlings to meet three objectives: 1) evaluate pathogenicity of two MPB-associated blue-stain fungi; 2) evaluate phytotoxicity of tree injection products; 3) evaluate the anti-fungal activity of tree injection products, in vitro and in vivo, toward the associated blue-staining fungi. To evaluate pathogenicity, seedlings were inoculated with Grosmannia clavigera or Leptographium longiclavatum, common fungal associates of MPB. Seedling mortality at four months after inoculation was 50% with L. longiclavatum and 90% with G. clavigera, both significantly higher than controls and thereby demonstrating pathogenicity. Phytotoxic effects of TREE-äge®, Alamo®, and Arbotect® were evaluated by stem injection; no phytotoxic effects were observed. Anti-fungal properties of the same three products were evaluated in vitro against G. clavigera, where Alamo was most active. Co-inoculation of G. clavigera and L. longiclavatum into seedlings after a stem injection of Alamo showed significantly less mortality and lesion formation than either species alone. Results support the hypothesis that MPB blue-stain associates, particularly G. clavigera, promote death of WWP when attacked by MPB. These findings suggest that the administration of a fungicide with insecticide for tree protection against bark beetles may be advantageous.
Eutypa Dieback and ESCA - Trunk Necrosis and Dieback Diseases of Grapevines in Serbia
Aćimović, Srđan G.; Delibašić, Goran; Schilder, Annemiek; Tanovic, Brankica (University of Novi Sad, Serbia, 2008-12-22)

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