Scholarly Works, Virginia Agricultural Experiment Station

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


Recent Submissions

Now showing 1 - 20 of 352
  • Improved Canker Processing and Viability Droplet Digital PCR Allow Detection of Erwinia amylovora Viable Nonculturable Cells in Apple Bark
    Dhar, Bidhan Chandra; Delgado Santander, Ricardo; Aćimović, Srđan G. (MDPI, 2024-02-12)
    The bacterium Erwinia amylovora causes fire blight and continues to threaten global commercial apple and pear production. Conventional microbiology techniques cannot accurately determine the presence of live pathogen cells in fire blight cankers. Several factors may prevent E. amylovora from growing on solid culture media, including competing microbiota and the release of bacterial-growth-inhibitory compounds by plant material during sample processing. We previously developed a canker processing methodology and a chip-based viability digital PCR (v-dPCR) assay using propidium monoazide (PMA) to bypass these obstacles. However, sample analysis was still time-consuming and physically demanding. In this work, we improved the previous protocol using an automatic tissue homogenizer and transferred the chip-based v-dPCR to the BioRad QX200 droplet dPCR (ddPCR) platform. The improved sample processing method allowed the simultaneous, fast, and effortless processing of up to six samples. Moreover, the transferred v-ddPCR protocol was compatible with the same PMA treatment and showed a similar dynamic range, from 7.2 × 102 to 7.6 × 107 cells mL−1, as the previous v-dPCR. Finally, the improved protocol allowed, for the first time, the detection of E. amylovora viable but nonculturable (VBNC) cells in cankers and bark tissues surrounding cankers. Our v-ddPCR assay will enable new ways to evaluate resistant pome fruit tree germplasm, further dissect the E. amylovora life cycle, and elucidate E. amylovora physiology, epidemiology, and new options for canker management.
  • Pre-Harvest Corn Grain Moisture Estimation Using Aerial Multispectral Imagery and Machine Learning Techniques
    Jjagwe, Pius; Chandel, Abhilash K.; Langston, David (MDPI, 2023-12-18)
    Corn grain moisture (CGM) is critical to estimate grain maturity status and schedule harvest. Traditional methods for determining CGM range from manual scouting, destructive laboratory analyses, and weather-based dry down estimates. Such methods are either time consuming, expensive, spatially inaccurate, or subjective, therefore they are prone to errors or limitations. Realizing that precision harvest management could be critical for extracting the maximum crop value, this study evaluates the estimation of CGM at a pre-harvest stage using high-resolution (1.3 cm/pixel) multispectral imagery and machine learning techniques. Aerial imagery data were collected in the 2022 cropping season over 116 experimental corn planted plots. A total of 24 vegetation indices (VIs) were derived from imagery data along with reflectance (REF) information in the blue, green, red, red-edge, and near-infrared imaging spectrum that was initially evaluated for inter-correlations as well as subject to principal component analysis (PCA). VIs including the Green Normalized Difference Index (GNDVI), Green Chlorophyll Index (GCI), Infrared Percentage Vegetation Index (IPVI), Simple Ratio Index (SR), Normalized Difference Red-Edge Index (NDRE), and Visible Atmospherically Resistant Index (VARI) had the highest correlations with CGM (r: 0.68–0.80). Next, two state-of-the-art statistical and four machine learning (ML) models (Stepwise Linear Regression (SLR), Partial Least Squares Regression (PLSR), Artificial Neural Network (ANN), Support Vector Machine (SVM), Random Forest (RF), and K-nearest neighbor (KNN)), and their 120 derivates (six ML models × two input groups (REFs and REFs+VIs) × 10 train–test data split ratios (starting 50:50)) were formulated and evaluated for CGM estimation. The CGM estimation accuracy was impacted by the ML model and train-test data split ratio. However, the impact was not significant for the input groups. For validation over the train and entire dataset, RF performed the best at a 95:5 split ratio, and REFs+VIs as the input variables (rtrain: 0.97, rRMSEtrain: 1.17%, rentire: 0.95, rRMSEentire: 1.37%). However, when validated for the test dataset, an increase in the train–test split ratio decreased the performances of the other ML models where SVM performed the best at a 50:50 split ratio (r = 0.70, rRMSE = 2.58%) and with REFs+VIs as the input variables. The 95:5 train–test ratio showed the best performance across all the models, which may be a suitable ratio for relatively smaller or medium-sized datasets. RF was identified to be the most stable and consistent ML model (r: 0.95, rRMSE: 1.37%). Findings in the study indicate that the integration of aerial remote sensing and ML-based data-run techniques could be useful for reliably predicting CGM at the pre-harvest stage, and developing precision corn harvest scheduling and management strategies for the growers.
  • Using Aerial Spectral Indices to Determine Fertility Rate and Timing in Winter Wheat
    Oakes, Joseph; Balota, Maria; Cazenave, Alexandre-Brice; Thomason, Wade (MDPI, 2024-01-03)
    Tiller density is indicative of the overall health of winter wheat (Triticum aestivum L.) and is used to determine in-season nitrogen (N) application. If tiller density exceeds 538 tillers per m2 at GS 25, then an N application at that stage is not needed, only at GS 30. However, it is often difficult to obtain an accurate representation of tiller density across an entire field. Normalized difference vegetative index (NDVI) and normalized difference red edge (NDRE) have been significantly correlated with tiller density when collected from the ground. With the advent of unmanned aerial vehicles (UAVs) and their ability to collect NDVI and NDRE from the air, this study was established to examine the relationship between NDVI, NDRE, and tiller density, and to verify whether N could be applied based on these two indices. From 2018 to 2020, research trials were established across Virginia to develop a model describing the relationship between aerial NDVI, aerial NDRE, and tiller density counted on the ground, in small plots. In 2021, the model was used to apply N in small plots at two locations, where the obtained grain yield was the same whether N was applied based on tiller density, NDVI, or NDRE. From 2022 to 2023, the model was applied at six locations across the state on large scale growers’ fields to compare the amount of GS 25 N recommended by tiller density, NDVI, and NDRE. At three locations, NDVI and NDRE recommended the same N rates as the tiller density method, while at two locations, NDVI and NDRE recommended less N than tiller density. At one location, NDVI and NDRE recommended more N than tiller density. However, across all six locations, there was no difference in grain yield whether N was applied based on tiller density, NDVI, or NDRE. This study indicated that UAV-based NDVI and NDRE are excellent proxies for tiller density determination, and can be used to accurately and economically apply N at GS 25 in winter wheat production.
  • An Economic Evaluation of Alternative Methods to Manage Fire Blight in Apple Production
    Rickard, Bradley J.; Acimovic, Srdan; Fazio, Gennaro; Silver, Casey (NYSHS, 2023-04-01)
    Our research examined the economic implications of managing fire blight in apple production by using susceptible rootstocks or resistant rootstocks with and without protective sprays. Our results indicate that use Geneva® rootstocks across all incidence levels of fire blight considered gave superior economic outcomes compared to susceptible rootstocks or tree insurance for fire blight.
  • The identity of Neocnemodon calcarata (Loew) (Diptera: Syrphidae), a specialized flower fly predator of woolly apple aphid
    Bergh, J. Christopher; Marek, Paul E.; Short, Brent D.; Skevington, Jeffrey H.; Thompson, F. Christian (2023-03-05)
    The names and identities of the specialized flower fly predators of the Woolly Apple Aphid, Eriosoma lanigerum (Hausmann, 1802) are fixed. These predators, Neocnemodon calcarata (Loew, 1866) and Neocnemodon vitripennis (Meigen, 1822), are important biological control agents as they prey on both arboreal and root colonies of the aphid. A lectotype is designated for Pipiza calcarata Loew, 1866, and type notes of N. calcarata and N. vitripennis are provided.
  • Testing Novel Seed Treatments and Soil-Applied Insecticides Against Wireworm in Corn, 2023
    Bekelja, Kyle; Malone, Sean (Oxford University Press, 2024-01)
  • A Novel Insecticide, Isocycloseram, Shows Promise as an Alternative to Chlorpyrifos Against a Direct Pest of Peanut
    Bekelja, Kyle; Malone, Sean; Mascarenhas, Victor; Taylor, Sally V. (2024-01)
    Larvae of the southern corn rootworm (SCR) Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) are primary pests of peanut in the Virginia-Carolina region of the United States, and are relatively sporadic pests in southern states such as Georgia, Alabama, and Florida. Peanuts have strict quality standards which, when they are not met, crop value is diminished by more than 65%. Management of direct pests like SCR is therefore crucial to maintaining the economic viability of the crop. The soil-dwelling nature of SCR larvae complicates management due to difficulties associated with monitoring and predicting infestations. Non-chemical management options are limited in this system; preventative insecticide applications are the most reliable management strategy for at-risk fields. Chlorpyrifos was the standard product for larval SCR management in peanut until its registration was revoked in 2022, leaving no effective chemical management option for larvae. We tested a novel insecticide, isocycloseram, for its ability to reduce pod scarring, pod penetration, and non-SCR pod damage in field studies conducted in Suffolk, Virginia in 2020 – 2022. Overall injury was low in 2020 and 2022, and in 2022 there was not a significant effect of treatment. In 2021, two simulated chemigation applications of isocycloseram in July significantly reduced pod scarring and overall pod injury relative to chlorpyrifos and the untreated control. Our results suggest that isocycloseram may become an effective option for managing SCR in peanut, although more work is needed to understand the mechanisms by which it is effective as a soil-applied insecticide.
  • Enhancement of phenolics extraction from red algae (Kappaphycus spp.) using solid-state fermentation
    Norakma, M. N.; Zaibunnisa, A. H.; Wan Razarinah, W. A. R.; Zarei, Mohammad; Sobah, A.; Hamid, N.; Astuti, P. D. (Rynnye Lyan Resources, 2023-11-11)
    The effects of solid-state fermentation (SSF) on microbial growth contribute to the bio-enrichment and availability of phenolic compounds in different varieties of Kappaphycus spp. red algae through the action of hydrolytic enzymes produced are investigated. Three different red algae samples were used; K. striatum var. green flower (GF), K. alvarezii var. white giant (WG) and K. alvarezii var. purple giant (PG). SSF was performed using A. oryzae for 0 to 6 days at 30°C. Results obtained demonstrated that the highest (p<0.05) extraction of phenolics (10.022 mg GAE/g and 14.90 mg CE/g), and antioxidant properties (72.47% activity of DPPH radical scavenging and 18.23 mM/g FRAP value respectively) was obtained for GF sample at day 4 of fermentation. Cellulase, β-glucosidase, and xylanase were found to be responsible for enhancing phenolics and antioxidant activity of WG and GF varieties by releasing bound phenolics. However, for the PG sample, β-glucosidase showed a significant relationship with TPC and antioxidant activity.
  • Insects as Valuable Sources of Protein and Peptides: Production, Functional Properties, and Challenges
    Hasnan, Fatin Fayuni Binti; Feng, Yiming; Sun, Taozhu; Parraga, Katheryn; Schwarz, Michael; Zarei, Mohammad (MDPI, 2023-11-24)
    As the global population approaches 10 billion by 2050, the critical need to ensure food security becomes increasingly pronounced. In response to the urgent problems posed by global population growth, our study adds to the growing body of knowledge in the field of alternative proteins, entomophagy, insect-based bioactive proteolysates, and peptides. It also provides novel insights with essential outcomes for guaranteeing a safe and sustainable food supply in the face of rising global population demands. These results offer insightful information to researchers and policymakers tackling the intricate relationship between population expansion and food supplies. Unfortunately, conventional agricultural practices are proving insufficient in meeting these demands. Pursuing alternative proteins and eco-friendly food production methods has gained urgency, embracing plant-based proteins, cultivated meat, fermentation, and precision agriculture. In this context, insect farming emerges as a promising strategy to upcycle agri-food waste into nutritious protein and fat, meeting diverse nutritional needs sustainably. A thorough analysis was conducted to evaluate the viability of insect farming, investigate insect nutrition, and review the techniques and functional properties of protein isolation. A review of peptide generation from insects was conducted, covering issues related to hydrolysate production, protein extraction, and peptide identification. The study addresses the nutritional value and global entomophagy habits to elucidate the potential of insects as sources of peptides and protein. This inquiry covers protein and hydrolysate production, highlighting techniques and bioactive peptides. Functional properties of insect proteins’ solubility, emulsification, foaming, gelation, water-holding, and oil absorption are investigated. Furthermore, sensory aspects of insect-fortified foods as well as challenges, including Halal and Kosher considerations, are explored across applications. Our review underscores insects’ promise as sustainable protein and peptide contributors, offering recommendations for further research to unlock their full potential.
  • New Insights in the Detection and Management of Anthracnose Diseases in Strawberries
    Aljawasim, Baker D.; Samtani, Jayesh B.; Rahman, Mahfuzur (MDPI, 2023-10-27)
    Anthracnose diseases, caused by Colletotrichum spp., are considered to be among the most destructive diseases that have a significant impact on the global production of strawberries. These diseases alone can cause up to 70% yield loss in North America. Colletotrichum spp. causes several disease symptoms on strawberry plants, including root, fruit, and crown rot, lesions on petioles and runners, and irregular black spots on the leaf. In many cases, a lower level of infection on foliage remains non-symptomatic (quiescent), posing a challenge to growers as these plants can be a significant source of inoculum for the fruiting field. Reliable detection methods for quiescent infection should play an important role in preventing infected plants’ entry into the production system or guiding growers to take appropriate preventative measures to control the disease. This review aims to examine both conventional and emerging approaches for detecting anthracnose disease in the early stages of the disease cycle, with a focus on newly emerging techniques such as remote sensing, especially using unmanned aerial vehicles (UAV) equipped with multispectral sensors. Further, we focused on the acutatum species complex, including the latest taxonomy, the complex life cycle, and the epidemiology of the disease. Additionally, we highlighted the extensive spectrum of management techniques against anthracnose diseases on strawberries and their challenges, with a special focus on new emerging sustainable management techniques that can be utilized in organic strawberry systems.
  • A NitroPure Nitrocellulose Membrane-Based Grapevine Virus Sampling Kit: Development and Deployment to Survey Japanese Vineyards and Nurseries
    Nita, Mizuho; Jones, Taylor; McHenry, Diana; Bush, Elizabeth; Oliver, Charlotte; Kawaguchi, Akira; Nita, Akiko; Katori, Miyuki (MDPI, 2023-10-17)
    We developed a NitroPure Nitrocellulose (NPN) membrane-based method for sampling and storing grapevine sap for grapevine virus detection. We devised an efficient nucleic acid extraction method for the NPN membrane, resulting in 100% amplification success for grapevine leafroll-associated virus 2 (GLRaV2) and 3 (GLRaV3), grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine virus A, grapevine virus B, and grapevine red blotch virus (GRBV). This method also allowed the storage of recoverable nucleic acid for 18 months at room temperature. We created a sampling kit to survey GLRaV2, GLRaV3, and GRBV in Japanese vineyards. We tested the kits in the field in 2018 and then conducted mail-in surveys in 2020–2021. The results showed a substantial prevalence of GLRaV3, with 48.5% of 132 sampled vines being positive. On the other hand, only 3% of samples tested positive for GLRaV2 and none for GRBV.
  • Fruit Quality of Several Strawberry Cultivars during the Harvest Season under High Tunnel and Open Field Environments
    Patel, Hiral; Taghavi, Toktam; Samtani, Jayesh B. (MDPI, 2023-09-28)
    Parameters such as titratable acids (TA), total soluble solids (TSS), and their ratio (TSS/TA) are critical in determining strawberry fruit quality and the value of new cultivars. Ten strawberry cultivars were evaluated in two environments (open field and high tunnel) in the city of Virginia Beach. The objective was to evaluate the fruit quality characteristics (total soluble solids, titratable acidity TA, and total anthocyanin content) of newer strawberry cultivars grown in the annual hill plasticulture systems in coastal Virginia climatic conditions. Another objective was to measure the correlation between TA and a new digital meter (pocket acidity meter; PAM). Fruits were harvested weekly and TSS was measured using a refractometer. Acidity was measured using the pocket acidity meter and titratable acidity by a single sample titrimeter. Genetics significantly affected total anthocyanin content, TSS, TA, and acidity. The effect of the environments (high tunnel and open field) was not significant on TSS but significant on total anthocyanin content, TA, and acidity. “Flavorfest” had the highest and “Sweet Ann” the lowest anthocyanin content, TSS, and TA among the cultivars. The acidity (PAM data) showed a different level of correlation than TA, with a higher correlation for the open field than the high tunnel. On average, when outliers were removed, there was a regression of TA = 2.22(PAM) + 0.49 between the two data sets, with R2 = 0.47.
  • Plant Density Recommendations and Plant Nutrient Status for High Tunnel Tomatoes in Virginia
    Torres-Quezada, Emmanuel; Gandini-Taveras, Ricardo José (MDPI, 2023-09-22)
    Open-field tomatoes in Virginia are traditionally planted in a single row with 2 ft (0.60 m) of in-row spacing, resulting in a plant density of 4356 plants per acre (10,890 plants/ha). However, there has been increasing interest among small and medium-sized farmers in high tunnel production. In order to be profitable, farmers must maximize their yield per unit area and take advantage of the potential benefits of producing under high tunnels. A common approach under greenhouse conditions is to increase the planting density to enhance yield per area. However, high tunnel farmers often extrapolate open-field practices to their high tunnels as they believe both systems are closer related together than to greenhouse production. In those cases, high tunnel farmers could potentially be neglecting yield increases due to their planting density selection. Additionally, irrigation and fertilization management (fertigation) under high tunnels tend to be more efficient than open-field systems, as the frequency of application is increased with a lower volume per application. A higher efficiency of fertigation could alter plant yield responses, especially under traditional planting-density systems. Hence, this study aimed to identify the effect of high planting density on high tunnel tomatoes and their nutrient status on the Eastern Shore of Virginia. The experiment was established on a completely randomized block design with four replications, with 20 ft (6.09 m) experimental plots. We evaluated the combination of two in-row distances and single and double planting rows, with treatments consisting of 2 ft of in-row distance in a single row (4356 plants/acre—current open-field recommendation), 1.5 ft (0.45 m) of in-row distance in a single row (5808 plants/acre [14,520 plants/ha]), 2 ft of in-row distance in a double row (8712 plants/acre [21,780 plants/ha]), and 1.5 ft of in-row distance in a double row (11,616 plants/acre [29,040 plants/ha]). Summer-grown tomatoes produced on the Eastern Shore of Virginia under high tunnel conditions should be planted with 2 ft of in-row spacing and with a single row of plants per planting bed. Increasing the plant density or modifying the current recommended plant distribution could result in yield losses per plant between 32% and 46% and substantial increases in production costs compared with the traditional planting density. Throughout all treatments, tomato plants did not show deficient nutrient status. We hypothesized that irrigation water and pollination were the limiting factors that promoted a decrease in yield per plant for the high-density treatments.
  • Surveying North American Specialty Crop Growers' Current Use of Soilless Substrates and Future Research and Education Needs
    Fields, Jeb S.; Owen, James S.; Lamm, Alexa; Altland, James; Jackson, Brian; Oki, Lorence; Samtani, Jayesh B.; Zheng, Youbin; Criscione, Kristopher S. (MDPI, 2023-08-31)
    Many specialty crop growers are transitioning high-value crops from in-ground production to soilless culture due to the diminishing availability of fumigants, increasing pest pressure, extreme weather, and the need for flexible production practices. The objective of this study was to determine the research and educational needs of specialty crop growers who are transitioning to soilless substrates. North American growers were surveyed using an online instrument that incorporated Likert-type statement matrices, open-ended questions, and demographic questions. Additionally, two virtually led focus groups were conducted to further expand upon the quantitative findings with descriptive data. Respondents indicated the most important factors in considering whether to adopt soilless substrates were improving, managing, and reducing overall plant quality, disease management, and crop loss, respectively. The most important research needs were understanding the effects of substrates on crop quality and uniformity, fertilizer management, and economic costs and benefits/return on investment. In both the grower survey and focus groups, crop quality and uniformity were among the highest-scored responses. Food safety, disease and pest management, consumer perception, substrate disposal-related issues, transportation, and return-on-investment were also identified as important factors when considering soilless substrates.
  • Physiological Comparison of Two Salt-Excluder Hybrid Grapevine Rootstocks under Salinity Reveals Different Adaptation Qualities
    Gajjar, Pranavkumar; Ismail, Ahmed; Islam, Tabibul; Darwish, Ahmed G.; Moniruzzaman, Md; Abuslima, Eman; Dawood, Ahmed S.; El-Saady, Abdelkareem M.; Tsolova, Violeta; El-Kereamy, Ashraf; Nick, Peter; Sherif, Sherif M.; Abazinge, Michael D.; El-Sharkawy, Islam (MDPI, 2023-09-13)
    Like other plant stresses, salinity is a central agricultural problem, mainly in arid or semi-arid regions. Therefore, salt-adapted plants have evolved several adaptation strategies to counteract salt-related events, such as photosynthesis inhibition, metabolic toxicity, and reactive oxygen species (ROS) formation. European grapes are usually grafted onto salt-tolerant rootstocks as a cultivation practice to alleviate salinity-dependent damage. In the current study, two grape rootstocks, 140 Ruggeri (RUG) and Millardet et de Grasset 420A (MGT), were utilized to evaluate the diversity of their salinity adaptation strategies. The results showed that RUG is able to maintain higher levels of the photosynthetic pigments (Chl-T, Chl-a, and Chl-b) under salt stress, and hence accumulates higher levels of total soluble sugars (TSS), monosaccharides, and disaccharides compared with the MGT rootstock. Moreover, it was revealed that the RUG rootstock maintains and/or increases the enzymatic activities of catalase, GPX, and SOD under salinity, giving it a more efficient ROS detoxification machinery under stress.
  • Characterization of Boxwood Shoot Bacterial Communities and Potential Impact from Fungicide Treatments
    Li, Xiaoping; Tseng, Hsien Tzer; Hemmings, Ginger; Omolehin, Olanike; Taylor, Chad; Taylor, Amanda; Kong, Ping; Daughtrey, Margery; Gouker, Fred; Hong, Chuanxue (American Society for Microbiology, 2023-04)
    Agrochemicals are important tools for safeguarding plants from invasive pathogens, insects, mites, and weeds. How they may affect the plant microbiome, a critical component of crop health and production, was poorly understood. Phyllosphere bacterial communities play important roles in plant fitness and growth. The objective of this study was to characterize the epiphytic and endophytic bacterial communities of boxwood shoots and determine how they may respond to commonly used fungicides. In early summer and early fall, shoot samples were collected immediately before and 1, 7, and 14days after three fungicides containing chlorothalonil and/or propiconazole were applied to the canopy. Total genomic DNA from shoot surface washings and surface-sterilized shoot tissues was used as the template for 16S rRNA metabarcoding, and the amplicons were sequenced on a Nanopore MinION sequencer to characterize the epiphytic and endophytic communities. The bacterial communities were phylogenetically more diverse on the boxwood shoot surface than in the internal tissue, although the two communities shared 12.7% of the total 1,649 identified genera. The most abundant epiphytes were Methylobacterium and Pantoea, while Stenotrophomonas and Brevundimonas were the dominant endophytes. Fungicide treatments had strong impacts on epiphytic bacterial community structure and composition. Analysis of compositions of microbiomes with bias correction (ANCOM-BC) and analysis of variance (ANOVA)-like differential expression (ALDEx2) together identified 312 and 1,362 epiphytes changed in abundance due to fungicide treatments in early summer and early fall, respectively, and over 50% of these epiphytes were negatively impacted by fungicide. The two chlorothalonil-based contact fungicides demonstrated more marked effects than the propiconazole-based systemic fungicide. These results are foundational for exploring and utilizing the full potential of the microbiome and fungicide applications and developing a systems approach to boxwood health and production. IMPORTANCE Agrochemicals are important tools for safeguarding plants from invasive pathogens, insects, mites, and weeds. How they may affect the plant microbiome, a critical component of crop health and production, was poorly understood. Here, we used boxwood, an iconic low-maintenance landscape plant, to characterize shoot epiphytic and endophytic bacterial communities and their responses to contact and systemic fungicides. This study expanded our understanding of the above-ground microbiome in ornamental plants and is foundational for utilizing the full benefits of the microbiome in concert with different fungicide chemistries to improve boxwood health. This study also sets an example for a more thorough evaluation of these and other agrochemicals for their effects on boxwood microbiomes during production and offers an expanded systems approach that could be used with other crops for enhanced integrated pest management.
  • Brewer’s Spent Grain with Yeast Amendment Shows Potential for Anaerobic Soil Disinfestation of Weeds and Pythium irregulare
    Liu, Danyang; Samtani, Jayesh; Johnson, Charles; Zhang, Xuemei; Butler, David M.; Derr, Jeffrey (MDPI, 2023-08-08)
    Anaerobic soil disinfestation (ASD) is a promising alternative to chemical fumigation for controlling soilborne plant pathogens and weeds. This study investigated the impact of brewer’s spent grain (BSG), a locally available carbon source, on various weed species and the oomycete pathogen Pythium irregulare in ASD. Two greenhouse studies were conducted using BSG and yeast at full and reduced rates in a completely randomized design with four replicates and two runs per study. In both studies, ASD treatments significantly decreased the seed viability of all weed species and the Pythium irregulare inoculum, while promoting higher cumulative anaerobicity compared to the non-treated control. The addition of yeast had a notable effect when combined with BSG but not with rice bran. When used in reduced carbon rates, yeast supplementation enhanced the efficacy of BSG, providing comparable control to the full rate for most weed species, including redroot pigweed, white clover, and yellow nutsedge. Interestingly, no ASD treatment affected the soil temperature. Furthermore, BSG treatments caused higher concentrations of volatile fatty acids compared to ASD with rice bran and the non-treated control. This finding suggests that the inclusion of yeast in ASD shows potential for reducing the carbon input required for effective soil disinfestation.
  • The impact of nitrogen treatment and short-term weather forecast data in irrigation scheduling of corn and cotton on water and nutrient use efficiency in humid climates
    Sangha, Laljeet; Shortridge, Julie; Frame, William (Elsevier, 2023-06)
    Irrigation adoption is increasing in humid regions to offset short-term dry periods, especially at the peak of the growing season. Low soil moisture at the peak growth stage impacts yield and limits the plant's capacity to uptake nitrogen, resulting in low nutrient use efficiency (NUE). However, heavy rainfall on fields with supple-mental irrigation may result in waterlogging and surface runoff, leading to nutrient leaching and runoff. This ultimately can lead to lower NUE, poor water use efficiency (WUE), reduced yields, and water quality impacts. This makes irrigation management challenging in humid regions, as irrigators must avoid both limited and excess water conditions. This field study aimed to develop and test an irrigation management methodology using real-time soil water availability, crop physiological status, water needs, and short-term weather forecasts information from National Weather Service. A rule-based approach determined by soil moisture depletion and short-term weather forecasts was used to trigger irrigation to avoid both stress and excess water conditions. This method was tested in two years of field trials in Suffolk, Virginia to quantify its impacts on yield, NUE, WUE, and financial returns in corn and cotton under four nitrogen application treatments. The relative impact of irrigation and nitrogen treatment was quantified using mixed effects models. The yield, NUE and WUE were impacted by both precipitation and irrigation patterns. Significantly different yields were observed under Nrates treatments for both corn and cotton. The trends of economic returns were similar to yield and were significantly different between recent and historic prices. This study also discusses the impacts of reliability and practical challenges of using Weather Informed irrigation in a field study.
  • Effect of sire fecal egg count estimated breeding value on parasite resistance traits in Haemonchus contortus infected Katahdin lambs
    Wright, Donald L.; Greiner, Scott P.; Bowdridge, Scott A. (Elsevier, 2023-06)
    In the midst of anthelmintic resistance, genetic resistance to gastrointestinal nematodes (GIN) in lambs could reduce anthelmintic requirements; therefore, the fecal egg count (FEC) estimated breeding value (EBV) was developed as a measure of genetic merit for parasite burden. One of the first breeds to effectively implement the FEC EBV was Katahdin. To better understand the relationship between the FEC EBV and Haemonchus contortus (Hc) challenge infection, a divergent mating scheme was established with extremely high (High FEC, n = 5) or extremely low (Low FEC, n = 5) FEC EBV Katahdin rams over 2 years. Purebred lambs sired by these rams were born beginning in mid-March and managed on pasture until approximately 120 days of age. A primary infection was established based on FEC during this period. At this point, lambs (n = 109 in Year 1, n = 114 in Year 2) were removed from pasture, treated with an anthelmintic to reduce FEC and transported to the Animal Sciences Farm at West Virginia University. After a rest period, lambs were given 10,000 (Year 1) or 5000 (Year 2) Hc L3. Body weights, FEC, and packed cell volume were collected weekly. Lambs were harvested (n = 60/year) at 5 weeks post-infection. Abomasum worm counts were determined, and worm length was measured using Image J. Sta-tistical analysis was performed by year using the Mixed Model procedure of SAS (SAS Institute, Cary, NC) with fixed effects of sire EBV type. Change in FEC after the prepatent period was greater in Year 1 High FEC-sired lambs compared to Low FEC-sired lambs (210 vs. 34 eggs/g, respectively; P < 0.05). At harvest in Year 2, a greater proportion of Low FEC-than High FEC-sired lambs had worm counts of zero (P < 0.05). Worm fecundity was lower in lambs sired by Low FEC rams (P < 0.05). Taken together, sire selection for low FEC EBV will lower FEC and worm count and improve GIN resistance in progeny.
  • Boxwood phyllosphere fungal and bacterial communities and their differential responses to film-forming anti-desiccants
    Li, Xiaoping; Omolehin, Olanike; Hemmings, Ginger; Tseng, Hsien T.; Taylor, Amanda; Taylor, Chad; Kong, Ping; Daughtrey, Margery; Luster, Douglas; Gouker, Fred; Hong, Chuanxue (2023-08-12)
    Background Anti-desiccant is a class of agrochemicals widely used to protect plants from water stresses, rapid temperature variations, heat and sunburn, frost and freeze damages, transplant shock, and pathogen and pest attack. Although anti-desiccants are generally considered non-toxic to organisms, it is unclear whether they may impact the phyllosphere microbial communities. In this study, three film-forming anti-desiccant products, TransFilm, Vapor Gard, and Wilt-Pruf were applied to the canopy of two boxwood cultivars ‘Vardar Valley’ and ‘Justin Brouwers’ on April 13 and August 26, 2021. Shoot samples were collected from boxwood plants treated with each of the three products, as well as nontreated control on June 16, August 26 (before the second treatment), and October 18. Microbial and plant genomic DNA was isolated together and 16S rRNA gene and the extended internal transcribed spacer regions were amplified with PCR and sequenced on a Nanopore MinION platform for bacterial and fungal identification. Results Bacterial communities were more diverse than fungal communities. At the phylum level, the boxwood phyllosphere was dominated by Proteobacteria and Ascomycota; at the genus level, Methylobacterium and Shiraia were the most abundant bacteria and fungi, respectively. Among the three film-forming anti-desiccants, Vapor Gard and Wilt-Pruf had more impact than TransFilm on the microbial communities. Specifically, broader impacts were observed on fungal than bacterial community composition and structure, with most affected fungi being suppressed while bacteria promoted. Conclusion This study addressed several major knowledge gaps regarding boxwood phyllosphere microbiota and the impact of anti-desiccants on plant microbiome. We identified diverse microbial communities of boxwood, a major evergreen woody crop and an iconic landscape plant. We also found differential effects of three film-forming anti-desiccants on the composition and structure of bacterial and fungal communities. These findings advanced our understanding of the associated microbiome of this landmark plant, enabling growers to fully utilize the potentials of microbiome and three anti-desiccants in improving boxwood health and productivity.