Progress Curve Research Articles

Elucidating the Etiology and Temporal Progress of Rust on Physic Nut Genotypes and Their Relationship with Environmental Conditions in Ecuador

Physic nut (Jatropha curcas L.) has emerged as a promising fruit crop in Ecuador, but the recent identification of rust poses a potential threat to its productive development. This study focused on elucidating the morphological aspects of the basidiomycete and assessing rust intensity across different canopy levels of physic nut hybrids and genotypes under field and semi-controlled conditions in Manabí, Ecuador. For the first time, this study confirms that Phakopsora arthuriana should be responsible for rust on physic nut in Ecuador based on the characteristics of the fungal structures. Rust incidence was 100% across all canopy layers, with the lower and middle canopies exhibiting higher severity and lesion numbers than the upper canopy. Using the Weibull nonlinear distribution model, we epidemiologically modeled disease progression, revealing that hybrid JAT 001100 displayed the highest temporal progress, recording 15% severity and an area under the disease progression curve of 3228.9 units. Promising genotypes CP-041 and CP-052 demonstrated lower rust intensity. Environmental parameters, including dew point, temperature, precipitation, and relative humidity, were correlated with rust severity and lesion numbers. In greenhouse assays, hybrid JAT 001165 showed higher severity, whereas JAT 001103 and JAT 001164 had more lesions than other genotypes. In contrast, promising genotypes CP-041 and CP-052 consistently exhibited lower rust intensity in both field and greenhouse environments. This study demonstrated that P. arthuriana could be epidemiologically modeled with the Weibull model, providing crucial insights into the dynamic interplay between rust infection and physic nut hybrids and genotypes under diverse conditions in the Manabí region of Ecuador.

Treatment and Long-Term Safety Outcomes of Peptide Receptor Radionuclide Therapy for Metastatic Neuroendocrine Tumours: An Asian Experience

Purpose: Peptide receptor radionuclide therapy (PRRT) is a targeted molecular therapy used to treat neuroendocrine tumours (NETs). It has been shown to be effective and well tolerated in patients with metastatic NETs in several centres in the USA, Europe, and Australia. Tolerability and efficacy data emerging from Asian centres remain few. Epidemiological evidence suggests that there are differences in neuroendocrine neoplasms between the population groups. We aim to describe the treatment and safety outcomes of PRRT in the Asian population. Methods: One hundred and seven (107) patients with metastatic NETs who had undergone PRRT treatment from January 2012 to March 2019 were included in this retrospective study. The response rates using RECIST 1.1 and qualitative analysis were examined. The overall and progression-free survival curves were also evaluated. Results: The median progression-free survival was 49 months. Response assessment after completion of treatment showed that 33 (37.9%) of 87 patients had partial or complete response. Subgroup analysis comparing high- and low-grade NET showed that there was a significant difference in the time to progression curves. Comparison of the number of cycles and progression-free and overall survival also showed a significant difference. Ten patients (9%) had grade 3 or more haematological toxicities. Four patients (4%) had grade 3/4 hepatobiliary toxicities, although the presence of extensive liver metastases was a confounding factor. None of the patients had grade 3/4 acute kidney injury. Conclusion: Our results show that PRRT is safe and effective in the treatment of metastatic NET in the Asian population. There was a significant difference in the progression-free survival curves between low-grade and high-grade NET and in the progression-free and overall survival comparing the number of cycles received.

3D prediction of curve progression in adolescent idiopathic scoliosis based on biplanar radiological reconstruction.

This systematic review aims to identify 3D predictors derived from biplanar reconstruction, and to describe current methods for improving curve prediction in patients with mild adolescent idiopathic scoliosis. A comprehensive search was conducted by three independent investigators on MEDLINE, PubMed, Web of Science, and Cochrane Library. Search terms included "adolescent idiopathic scoliosis","3D", and "progression". The inclusion and exclusion criteria were carefully defined to include clinical studies. Risk of bias was assessed with the Quality in Prognostic Studies tool (QUIPS) and Appraisal tool for Cross-Sectional Studies (AXIS), and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. In all, 915 publications were identified, with 377 articles subjected to full-text screening; overall, 31 articles were included. Torsion index (TI) and apical vertebral rotation (AVR) were identified as accurate predictors of curve progression in early visits. Initial TI > 3.7° and AVR > 5.8° were predictive of curve progression. Thoracic hypokyphosis was inconsistently observed in progressive curves with weak evidence. While sagittal wedging was observed in mild curves, there is insufficient evidence for its correlation with curve progression. In curves with initial Cobb angle < 25°, Cobb angle was a poor predictor for future curve progression. Prediction accuracy was improved by incorporating serial reconstructions in stepwise layers. However, a lack of post-hoc analysis was identified in studies involving geometrical models. For patients with mild curves, TI and AVR were identified as predictors of curve progression, with TI > 3.7° and AVR > 5.8° found to be important thresholds. Cobb angle acts as a poor predictor in mild curves, and more investigations are required to assess thoracic kyphosis and wedging as predictors. Cumulative reconstruction of radiographs improves prediction accuracy. Comprehensive analysis between progressive and non-progressive curves is recommended to extract meaningful thresholds for clinical prognostication.

Abstract 2061: A proven activity-based workflow for the identification and characterization of time-dependent kinase inhibitors using a continuous assay format

Abstract Time-dependent inhibitors (TDIs) of enzyme targets offer distinct advantages for the development of potent and selective compounds with favorable pharmacokinetic and pharmacodynamic properties. Such inhibitors are characterized by non-linear progress curves: after an initial inhibited velocity, a rate constant governs the transition to a final steady-state reaction rate of the inhibited enzyme. A final rate of zero indicates irreversible inhibition, whereas a non-zero final rate indicates slow-binding inhibition. Characterizing these inhibitory modes of action is enabled with a continuous assay format that avoids the common pitfalls and misleading results seen with end-point assays. A continuous assay format enables efficient and robust determination of the kinetic parameters required to drive structure-activity relationship optimization to streamline the development of more effective drugs. It is important to note that simple IC50s for TDIs will not suffice, and can, indeed, also be misleading. We have developed a robust three-step workflow based on kinetic catalytic activity measurements to quickly identify and characterize TDIs. First, dose-response experiments are conducted with and without an enzyme-inhibitor preincubation step. The curvature of the reaction progress curve in the non-preincubated experiment and a shift in IC50 from the preincubated experiment are indicative of TDI. In the absence of TDI, simple IC50s are reported with, if possible, Ki values. If TDI is present, a second experiment is conducted to assess compound reversibility using either a jump-dilution protocol or a novel free-compound clearance method that uses gel filtration spin columns or spin plates. In either protocol, forward progress curve analysis is used to monitor the recovery of enzymatic activity after dilution of inhibitor in solution. Lastly, the potency of the inhibitor is evaluated using kinetic experiments tailored to the nature of the inhibition – either reversible or irreversible. If reversible, then the rate constant from the reversibility experiment is used to determine the residence time of the molecule. If irreversible, then a 24-point dose-response experiment with serial 1.5-fold dilutions is performed, and all the progress curves are globally fit to determine kinact/KI, and, if possible, kinact and KI separately. The method will be fully described through the characterization of known EGFR inhibitors of three inhibition types: fast-off (Gefitinib), slow binding (Lapatinib), and irreversible (Osimertinib). Citation Format: Earl May, Daniel Urul, Khanh Huynh, Susan Cornell-Kennon, Venkatesh Nemmara, Zhibing Lu, Samuel Hoare, Michelle Lyles, Erik Schaefer. A proven activity-based workflow for the identification and characterization of time-dependent kinase inhibitors using a continuous assay format [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2061.

Use of interactive mathematical simulations in Fundamentals of Biochemistry, a LibreText online educational resource, to promote understanding of dynamic reactions.

Biology is perhaps the most complex of the sciences, given the incredible variety of chemical species that are interconnected in spatial and temporal pathways that are daunting to understand. Their interconnections lead to emergent properties such as memory, consciousness, and recognition of self and non-self. To understand how these interconnected reactions lead to cellular life characterized by activation, inhibition, regulation, homeostasis, and adaptation, computational analyses and simulations are essential, a fact recognized by the biological communities. At the same time, students struggle to understand and apply binding and kinetic analyses for the simplest reactions such as the irreversible first-order conversion of a single reactant to a product. This likely results from cognitive difficulties in combining structural, chemical, mathematical, and textual descriptions of binding and catalytic reactions. To help students better understand dynamic reactions and their analyses, we have introduced two kinds of interactive graphs and simulations into the online educational resource, Fundamentals of Biochemistry, a LibreText biochemistry book. One is available for simple binding and kinetic reactions. The other displays progress curves (concentrations vs. time) for simple reactions and complex metabolic and signal transduction pathways. Users can move sliders to change dissociation and kinetic constants as well as initial concentrations and see instantaneous changes in the graphs. They can also export data into a spreadsheet for further processing, such as producing derivative Lineweaver-Burk and traditional Michaelis-Menten graphs of initial velocity (v0) versus substrate concentration.

Abstract 1666: A novel sox-based continuous and homogeneous assay for the discovery of inhibitors of inactive and active AKT

Abstract Introduction: The activity of protein kinases plays a critical role in the aberrant activation of oncogenic signaling pathways which can drive tumorigenesis and malignant transformation in cancer. AKT has been shown to be both upregulated and mutated in cancer cells allowing it to serve as a driver of cancer cell growth and progression. Inhibition of AKT activation and activity are both attractive targets for effective cancer drug discovery. Experimental Procedures: We developed continuous, homogeneous assays for unactive AKTs. A peptide substrate, modified with a sulfonamido-oxine fluorophore (Sox), utilizes chelation-enhanced fluorescence to enable a real-time readout of AKT-driven phosphorylation. First, a subset of 30,000 Sox-containing sequences were evaluated for AKT substrate candidates, selecting for assay robustness and specificity. A physiologically relevant peptide substrate was identified and used to develop a kinetic assay to monitor AKT1 activation and activity. Unactive AKT1 was incubated with DOPS/DOPC and PIP3, which mimics the plasma membrane, allowing the PH domain of AKT to bind, leading to a conformational change that enables full activation of AKT by PDK1 and MK2. Upon assay initiation, active AKT phosphorylates the sensor peptide, and the resulting signal is read in kinetic mode using a fluorescence intensity readout. First derivative plots for each progress curve were generated; the slope of the linear regions of each plot, representing acceleration towards a steady-state, were used to determine relative rates of activation for each AKT. Results: We developed a novel assay for AKT activation and substrate phosphorylation utilizing AQT0076, DOPS/DOPC, PIP3, PDK1, and MK2. With a mix of classical AKT inhibitors and allosteric inhibitors that rely on an inactive “PH-in” conformation, we demonstrated inhibition and quantified inhibitor potency of both active “PH-out” AKT activity and inactive “PH-in” AKT activation via dose-response measurements of steady-state rate and rate acceleration, respectively. Conclusions: A robust, homogeneous assay was developed to simultaneously monitor AKT activation and substrate phosphorylation kinetically over time. Through a continuous assay, we captured both steady-state rates and rate acceleration as a function of inhibitor concentration, allowing for accurate quantitation of both classes of AKT inhibitors in a single experimental format. With some inhibitors, we observed potencies that matched reported literature values, while with others we observed marked differences that may reflect a more physiological context that could translate through to higher efficacy in the clinic. This novel assay format provides a new tool that can be used in drug discovery to generate more effective next generation inhibitors of both AKT activation and subsequent substrate phosphorylation to prevent cancer cell growth and progression. Citation Format: Susan Cornell-Kennon, Daniel Urul, Matthew Hakar, Hayley McMahon, Khanh Huynh, Earl May, Erik Schaefer. A novel sox-based continuous and homogeneous assay for the discovery of inhibitors of inactive and active AKT [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1666.

Grain Yield and Quality Losses Caused by Tan Spot in Wheat Cultivars in Australia

Tan spot (TS), known in Australia as yellow leaf spot, is caused by the fungal pathogen Pyrenophora tritici-repentis, a major foliar disease of wheat. Four experiments were conducted between 2016 and 2017 in two different climatic zones of southeastern Australia to determine the impact of TS on grain yield and quality in six wheat cultivars with different resistance ratings. In each experiment, high and low TS disease scenarios were applied to each cultivar. Disease severity was assessed as either whole-plot percentage leaf area affected (%LAA) or top three leaf (flag to flag-2) %LAA. Whole-plot %LAA was analyzed using both repeated measurements and area under the disease progress curve (AUDPC). For whole-plot %LAA, the repeated measurements identified differences in epidemic progression at key growth stages not identified through AUDPC. Both AUDPC and end-of-season flag to flag-2 %LAA were negatively correlated with grain yield and screenings. Increased rainfall impacting disease development and number of rain days above 5 mm increased TS severity across both climatic zones. Cultivar resistance ratings influenced grain yield loss, with moderately resistant, moderately susceptible, and susceptible cultivars losing up to 6, 18, and 24% grain yield, respectively. High disease significantly increased screenings by up to 1, 3, and 5% for moderately resistant, moderately susceptible, and susceptible cultivars, respectively. This study demonstrated that TS can cause significant grain yield losses in southeastern Australia, and a minimum cultivar rating of moderate resistance to moderate susceptibility was required to prevent severe TS and associated grain yield and quality losses. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Reaction of Selected Citrus Cultivars to Pseudocercospora Leaf and Fruit Spot Disease Under Natural Infection in Northern Uganda

Citrus is an important crop among many resource constrained subsistence farmers living in rural areas of Uganda. Citrus production is affected mainly by drought, declining soil fertility, pests and diseases. Among diseases, citrus leaf and fruit spot disease caused by fungus Pseudocercospora angolensis is currently one of the major constraints to the production of citrus in Uganda where millions of people rely on the crop for nutritional security and household income. The disease can lead to 50-100% fruit yield loss depending on environmental conditions, disease management and weather conditions. In order to identify resistance to P. angolensis, a study was conducted to identify variability for citrus leaf and fruit spot resistance from adapted commercial cultivars as an initial step in developing integrated disease management strategy. Six cultivars were assessed. The screening was under natural infection conditions in disease hot spots in northern Uganda in 2014a and 2014b seasons. The results showed significance difference (p &amp;lt; 0.01) for Area Under Disease Progressive Curve (AUDPC) for number of leaves with P. angolesnis symptoms and number of lesions. Subsequently, the study identified Kuno as resistant and Tangelo as less susceptible to Pseudocercospora leaf and fruit spot infection, and they could be recommended for citrus leaf and fruit spot disease control.

Progressive coronal caudal curve after corrective osteotomies for congenital cervicothoracic scoliosis: incidence and predictors.

Postoperative progressive coronal caudal curve (PCC) was characterized by a postoperative de novo caudal S-curve ≥ 20° following congenital cervicothoracic scoliosis (CTS) corrective osteotomies, and at least 20° greater than the preoperative measurement, while the incidence was uncertain and the pathogenesis was equivocal. The objective of this study was to investigate the morbidity and potential factors contributing to PCC following CTS surgery. This study reviewed 72 CTS patients between 2005 and 2021. Patients were categorized into two groups according to the absence or presence of PCC at last follow-up, namely the nonprogressive curve group (NPC-group) and the progressive curve group (PC-group). Demographics, radiographic data and the Scoliosis Research Society-22 (SRS-22) questionnaire results were reviewed. Multivariate linear regression analyses were utilized to determine possible predictors for PCC. PCC was observed in 11 (15%) of the total 72 patients. Compared with the NPC-group, the PC-group exhibited greater postoperative residual local curve (24.0 ± 9.7° vs. 9.1 ± 4.4°, P < 0.001), upper instrumented vertebra (UIV) tilt (16.9 ± 7.4° vs. 6.2 ± 3.7°, P < 0.001), T1 tilt (14.3 ± 9.4° vs. 6.6 ± 3.9°, P = 0.022) and neck tilt (10.1 ± 6.7° vs. 3.7 ± 2.5, P = 0.009). The multivariable linear regression demonstrated that the larger postoperative UIV tilt, residual local curve and neck tilt were associated with PCC. In addition, patients with PCC showed lower SRS-22 scores in terms of pain, mental health, self-image and satisfaction (P < 0.05). The morbidity of PCC was 15% in CTS patients who underwent corrective osteotomies. Greater residual local curve, postoperative UIV tilt and neck tilt were identified as predictors for PCC.

Variations Among Crop Seasons and Inoculum Availability Have a Higher Impact on Grapevine Rust Epidemics than Training Systems or Plastic Cover.

Canopy management practices can be effective as part of the integrated management of grapevine diseases. This study aimed to determine whether training systems and plastic covers can contribute to prevent Asian grapevine leaf rust (AGLR) development. Additionally, the influence of crop season and inoculum availability on AGLR development was investigated. Six-season experiments were carried out to characterize 16 epidemics that developed from natural inoculum (NI) or artificial inoculum (AI) sources (NI + AI), conducted in different training systems and with or without the plastic cover. The Richards model was fitted to each AGLR disease progress curve to estimate and compare the onsets and intensities of epidemics using eight curve elements. Principal components analysis (PCA) identified the incidence progress rate, the area under the severity progress curve, final disease severity, time to disease onset, and time to reach the inflection point as the main descriptors for AGLR epidemics. The results showed that AGLR epidemic development was related mainly to differences in inoculum availability and climatic conditions throughout the seasons and to a lower extent to the training system and plastic cover. The earliest disease onset was observed in epidemics when the NI was supplemented with an AI source. Differences in AGRL intensity were correlated to accumulated precipitation, being less severe in autumn-winter than in the spring-summer season. The present findings provided a better understanding of the structure and the seasonal variation of AGLR in cultivar 'Niagara Rosada'. The strategies for reducing and/or delaying inoculum buildup among seasons are discussed.

Plant Growth, Fruit Yield, and Tomato Leaf Curl Disease of High Tunnel Organic Tomato Affected by Shade Net and Plastic Mulch Color

There is an increasing interest in producing organic tomatoes (Solanum lycopersicum) in high tunnels (HTs) in the southeast United States. HTs are unheated, passively cooled structures that allow tomato growers to harvest high-quality fruit out of season. However, excessive temperatures inside HTs may negatively impact tomato plant growth and fruit yield. Shade nets have been reported to reduce temperatures inside the HTs. Plastic mulch color has also significantly influenced plant growth and yield under high-temperature conditions. This study aimed to determine the effects of shade net color and plastic mulch color on plant growth, fruit yield, and incidence of tomato yellow leaf curl disease (TYLC) in ‘Red Snapper’ tomato grown in HTs under elevated temperatures (summer-fall) in southern Georgia, USA. Organic ‘Red Snapper’ tomato seedlings were transplanted in HTs in 2019 (Season 1) and 2020 (Season 2). The design was a split-plot randomized block where the main plots were externally mounted shade nets (black, silver, and unshaded; 30% shade factor), and the subplots were plastic mulches (black and white). Compared with black mulch, white mulch improved plant height and stem diameter but did not influence fruit yields. Shade nets reduced HT air temperature and root zone temperature (RZT) but did not affect plant height and stem diameter. The diminished photosynthetic photon flux density (PPFD) under the shade nets reduced marketable fruit yield. Thus, shade nets are not recommended once heat challenges do not limit HT tomato production in Georgia (after about mid-October). Shade nets and plastic mulch inconsistently affected TYLC incidence, severity, and area under the disease progress curve (AUDPC). Additional fruit yield reductions occurred due to TYLC because the incidence was 100% 6 weeks after transplanting. Preliminary insect data showed that shade net treatments had similar sweetpotato whitefly (Bemisia tabaci) numbers. The high TYLC incidence indicates that ‘Red Snapper’ may not be suitable for fall HT tomato production in the southeast United States. More research on shading and heat stress management in HT organic tomato production is necessary.

Early boosting of genetically improved Falcataria moluccana with mycorrhiza for better growth and disease tolerance

Falcataria moluccana is a widespread species that grows rapidly in Indonesia and produces timber used for carpentry. Nonetheless, this species is especially susceptible to gall rust disease. To find plants that can handle rust, a mix of breeding with progeny experiments and forest management methods, like arbuscular mycorrhiza (AM), were used. The point of this study is to find out if adding AM changes how F. moluccana seedlings grow and how they react to gall rust disease, both those that have been improved and those that have not. We will also look at the response by calculating the area under disease progress curves (AUDPC) value for rust disease to grow in F. moluccana seedlings. The experimental design comprised four different treatments, including varying quantities of mycorrhizae, as well as four different seed sources. For the mycorrhizal inoculation experiments, there was a control group and three treatment groups. The treatment groups got 5, 10, and 15 g of mycorrhiza per polybag, respectively. The seeds used in this study were sourced from two unimproved families, namely Java and Solomon, as well as two genetically improved families, F63 and F77. This study revealed that mycorrhizal application affects the growth of F. moluccana seedlings and significantly reduces both disease incidence and severity. The application of mycorrhiza reduces the disease incidence and severity; the AUPDC value of seedlings with mycorrhiza added is four times lower than that of seedlings without mycorrhiza. The disease severity was highest for the unimproved Solomon seedlings, despite the fact that the source of seeds had little impact on the disease incidence. Meanwhile, the genetically improved seedlings demonstrated lower disease incidence and severity rates than seedlings without improvement, with an AUPDC value nearly half that of the unimproved seedling. In terms of diameter and height, F. mollucana seedlings derived from various seed sources were remarkably diverse, and seedlings with improvements grew much better than seedlings without improvements. This study shows how arbuscular mycorrhiza affects how well improved and unimproved F. moluccana seedlings deal with gall rust disease.

Biocontrol of Diplodia bulgarica, the causal agent of apple canker, using Trichoderma zelobreve.

Apple (Malus domestica Borkh) is one of the most consumed and nutritious fruits. Iran is one of the main producers of the apple in the world. Diplodia bulgarica is the major causal agent of apple tree decline in Iran. Biological control is a nature-friendly approach to plant disease management. Trichoderma zelobreve was isolated from apple trees infected with Diplodia bulgarica in West Azarbaijan province of Iran. The results showed that T. zelobreve strongly inhibited the colony growth of D. bulgarica. In vivo assay on detached branches of apple tree cv. Golden Delicious using T. zelobreve mycelial plug showed that canker length/stem length (CL/SL) and canker perimeter/stem perimeter (CP/SP) indices decreased by 76 and 69%, respectively, 21days after inoculation. Additionally, wettable powder formulation (WPF) containing the antagonistic fungus "T. zelobreve" decreased CL and CP/SP by 75 and 67%, respectively, 6months after inoculation. Moreover, canker progress curves and the area under the disease progress curve (AUDPC) supported these findings. The growth temperatures of the antagonist and pathogen were similar, indicating the adaptation of T. zelobreve for biocontrol of apple canker caused by D. bulgarica. The results also showed that T. zelobreve-based WPF stored at 25°C assure excellent shelf life at least 4months, allowing the bioproduct to be stored at room temperature, which is a great advantage and cost-effective option.

Relationships of crystallinity and reaction rates for enzymatic degradation of poly (ethylene terephthalate), PET.

Biocatalytic degradation of plastic waste is anticipated to play an important role in future recycling systems. However, enzymatic degradation of crystalline poly (ethylene terephthalate) (PET) remains consistently poor. Herein, we employed functional assays to elucidate the molecular underpinnings of this limitation. This included utilizing complementary activity assays to monitor the degradation of PET disks with varying crystallinity (XC), as well as determining enzymatic kinetic parameters for soluble PET fragments. The results indicate that an efficient PET-hydrolase, LCCICCG, operates through an endolytic mode of action, and that its activity is limited by conformational constraints in the PET polymer. Such constraints become more pronounced at high XC values, and this limits the density of productive sites on the PET surface. Endolytic chain-scissions are the dominant reaction type in the initial stage, and this means that little or no soluble organic product are released. However, endolytic cuts gradually and locally promote chain mobility and hence the density of attack sites on the surface. This leads to an upward concave progress curve; a behavior sometimes termed lag-phase kinetics.

In‐field climatic factors driving Sclerotinia head rot progression across different sunflower planting dates

AbstractSclerotinia head rot, caused by Sclerotinia sclerotiorum, is a major disease limiting sunflower production in tropical and subtropical agroecological zones. Sporadic outbreaks across South Africa have resulted in major losses, yet little is known about the in‐field climatic factors driving this infection. Short‐interval, staggered plantings have been proposed as a control method for Sclerotinia head rot, which help to limit the number of plants in a susceptible developmental stage during conducive environmental conditions. However, this complicates field management practices, especially if working at the fringes of a planting window due to delayed rains. This study aimed to investigate the effect of planting date on Sclerotinia head rot progression in monthly plantings across the summer period. Artificial mycelial plug inoculations were performed at the R5.9 flowering stage in an open field. Disease establishment, progression and severity were monitored at 3‐day intervals for 30 days. We show that disease establishment was delayed by low relative humidity or extreme low temperatures in the January and March planting dates where the first lesions were only observed 6 days post‐inoculation. Consistently high temperatures above 27°C also suppressed disease progression and produced low area under the disease progress curve (AUDPC) scores of 75.15 and 29.4 for the October and November planting dates, respectively. These findings suggest that regardless of season or location, selecting a planting date that ensures the sunflower bloom period aligns with the hottest, driest part of the season will probably suppress Sclerotinia head rot in regions with average summer highs above 27°C.

Effect of Breach Parameters and Progression Curves on Dam Failure Hydrograph

Effect of Breach Parameters and Progression Curves on Dam Failure Hydrograph

Chemical Control of Powdery Mildew of Bigleaf Hydrangea

The efficacy of the fungicide pydiflumetofen + difenoconazole (Postiva) was evaluated at varying application rates and intervals for the control of powdery mildew (Golovinomyces orontii, formerly Erysiphe polygoni) in bigleaf hydrangea (Hydrangea macrophylla ‘Nikko Blue’). Container-grown hydrangeas were arranged in a completely randomized design with six single-plant replications. Experiments were done in 2022 and 2023 under both greenhouse and shade house conditions (56% shade). Powdery mildew in hydrangea was developed naturally. Pydiflumetofen + difenoconazole at 1.1, 1.6, and 2.2 ml·L−1 and a standard fungicide azoxystrobin + benzovindiflupyr (Mural) at 0.5 g·L−1 were sprayed to runoff on 2-, 4-, and 6-week intervals. Plants that were not treated with fungicide served as the control. Plants were evaluated weekly for disease severity (0% to 100% foliage affected) and defoliation (0% to 100% defoliation). The season-long area under the disease progress curve (AUDPC) and defoliation progress curve (AUDFC) were calculated for the evaluation period. The initial and final plant height and width were recorded, and height and width increase were determined. Pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr significantly reduced final disease severity, AUDPC, and defoliation both in the greenhouse and shade house compared with control plants. In both greenhouse trials and the 2022 shade house trial, AUDFC was reduced in all treatments compared with the control plants. However, AUDFC was not reduced by all treatments in the 2023 shade house trial. Pooled over application intervals, the low rate of pydiflumetofen + difenoconazole was as effective as the medium and high rates of pydiflumetofen + difenoconazole and azoxystrobin + benzovindiflupyr in reducing final powdery mildew severity and AUDPC both in the greenhouse and shade house in both 2022 and 2023. No significant differences between application intervals were noted in final disease severity and progress. Control of powdery mildew with fungicides failed to increase plant dimensions (i.e., plant height and width) compared with the no fungicide control. Because all application rates and intervals of pydiflumetofen + difenoconazole provided comparable powdery mildew disease control, it is suggested that using a low rate of pydiflumetofen + difenoconazole with the longest application interval (6 weeks) is the most cost-effective approach for managing powdery mildew in bigleaf hydrangeas.

Fungicide strategies for Ramularia Leaf Spot control recommended in Uruguay and its residues in barley grains

Ramularia leaf spot (RLS) is primarily managed by foliar fungicide spraying, which can result in residues in the grain. In recent years, increasing attention has been paid to the risks these residues pose to consumers. This study aimed to evaluate the efficacy of fungicide management used for RLS control and their fungicide residues in barley grain. Four different alternatives of fungicide mixtures: fluxapyroxad + pyraclostrobin + epoxiconazole; pyraclostrobin + epoxiconazole + chlorothalonil; prothioconazole + trifloxystrobin, and isopyrazam + azoxystrobin, in three spray timings: GS33, GS47 and GS33+GS47, were evaluated in five field experiments. An untreated and a fully protected treatment were included. Fungicide residues, disease severity, control efficacy, area under the disease progress curve, and plump grain yield were calculated. All fungicide strategies adhered to food safety, complying with the Maximum Residue Limits established by Codex and the European Union. Effectiveness varied based on RLS development, application time, and number of applications. Fungicide treatments applied at GS33+GS47 were the most effective as the highest severity levels were observed at the stage after GS47 under the conditions studied. Plump grain yield only showed minimal differences in the late epidemic. The study emphasized the low risk of fungicide presence in grains, favoring efficacy when selecting RLS management options. Any changes in management or regulations should be carefully reviewed to maintain findings. The research underscored the compatibility of recommended fungicide treatments with food safety standards, highlighting the balance between disease control efficacy and consumer safety.

Non-Destructive Monitoring of Foliar Fungicide Efficacy with Hyperspectral Sensing in Grapevine.

Frequent fungicide applications are required to manage grapevine powdery mildew (Erysiphe necator). However, this practice is costly and has led to widespread fungicide resistance. A method of monitoring in-field fungicide efficacy could help growers maximize spray-interval length, thereby reducing costs and the rate of fungicide resistance emergence. The goal of this study was to evaluate if hyperspectral sensing in the visible to shortwave infrared range (400 to 2,400 nm) can quantify foliar fungicide efficacy on grape leaves. Commercial formulations of metrafenone, Bacillus mycoides isolate J (BmJ), and sulfur were applied on Chardonnay grapevines in vineyard or greenhouse settings. Foliar reflectance was measured with handheld hyperspectral spectroradiometers at multiple days post-application. Fungicide efficacy was estimated as a proxy for fungicide residue and disease control measured with the Blackbird microscopy imaging robot. Treatments could be differentiated from the untreated control with an accuracy of 73.06% for metrafenone, 67.76% for BmJ, and 94.10% for sulfur. The change in spectral reflectance was moderately correlated with the cube root of the area under the disease progress curve for metrafenone- and sulfur-treated samples (R2 = 0.38 and 0.36, respectively) and with sulfur residue (R2 = 0.42). BmJ treatment impacted foliar physiology by enhancing the leaf mass/area and reducing the nitrogen and total phenolic content as estimated from spectral reflectance. The results suggest that hyperspectral sensing can be used to monitor in-situ fungicide efficacy, and the prediction accuracy depends on the fungicide and the time point measured. The ability to monitor in-situ fungicide efficacy could facilitate more strategic fungicide applications and promote sustainable grapevine protection. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

An outbreak of Verticillium dahliae on sycamore maple in a forest stand in Slovenia

Verticillium dahliae Kleb., the causal agent of Verticillium wilts, is a devastating plant disease affecting many plant species. Fungus V. dahliae was detected in a partially artificially established Acer pseudoplatanus L. forest stand in central Slovenia. This finding incited further study about the risk of different sources of V. dahliae isolates for maples in forests and the pathogenicity of three V. dahliae isolates of different origins was tested on saplings of A. pseudoplatanus, A. platanoides L., and A. campestre L. The inoculated saplings exhibited disease symptoms, i.e., leaf necrosis and wilting. At the end of the pathogenicity test, typical xylem browning was visible on the cross-sections, and the pathogen was successfully re-isolated. The isolates showed significant differences in their pathogenicity to specific maple hosts, with the agricultural isolate (originated from bell pepper) being the most aggressive on all three maple species. The disease severity index (DSI) and relative area under the disease progress curve (rAUDPC), as well as the success of re-isolation, indicate that A. platanoides is the most susceptible to inoculation with V. dahliae. In addition, significant differences in sapling biomass were observed between treated and control plants. These results suggest that maples in forest stands are threatened by V. dahliae, and biosecurity measures should be considered and implemented in forest management to reduce the transmission and potential spread of the pathogen.