Your browser doesn't support javascript.
loading
: 20 | 50 | 100
1 - 20 de 90
1.
Plant Dis ; 2024 May 07.
Article En | MEDLINE | ID: mdl-38715156

Detection and quantification of pathogen propagules in the air or other environmental samples is facilitated by culture-independent assays. We developed a quantitative PCR assay for the hop powdery mildew fungus, Podosphaera macularis, for detection of the organism from air samples. The assay utilizes primers and a TaqMan probe designed to target species-specific sequences in the 28S large subunit (LSU) of the nuclear ribosomal rDNA. Analytical sensitivity was not affected by the presence of an exogenous internal control or potential PCR inhibitors associated with DNA extracted from soil. The level of quantification of the assay was between 200 and 350 conidia when DNA was extracted from a fixed number of conidia. The assay amplified all isolates of P. macularis tested and had minimal cross-reactivity with other Podosphaera species when assayed with biologically relevant quantities of DNA. Standard curves generated independently in two other laboratories indicated that assay sensitivity was qualitatively similar and reproducible. All laboratories successfully detected eight unknown isolates of P. macularis and correctly discriminated Pseudoperonospora humuli and a water control. The usefulness of the assay for air sampling for late-season inoculum of P. macularis was demonstrated in field studies in 2019 and 2020. In both years, airborne populations of P. macularis in hop yards were detected consistently and increased during bloom and cone development.

2.
Annu Rev Phytopathol ; 2024 May 09.
Article En | MEDLINE | ID: mdl-38724018

Plant disease epidemics often transcend land management boundaries, creating a collective-action problem where a group must cooperate in a common effort to maximize individual and group benefits. Drawing upon the social-ecological systems framework and associated design principles, we review variables of resource systems, resource units, actors, and governance systems relevant to collective action in plant health. We identify a need to better characterize how attributes of epidemics determine the usefulness of collective management, what influences actors' decisions to participate, what governance systems fit different plant health threats, and how these subsystems interact to lead to plant health outcomes. We emphasize that there is not a single governance structure that ensures collective action but rather a continuum of structures that depend on the key system variables identified. An integrated social-ecological systems approach to collective action in plant health should enable institutional designs to better fit specific plant health challenges.

3.
Phytopathology ; 114(5): 910-916, 2024 May.
Article En | MEDLINE | ID: mdl-38330057

The landscape of scientific publishing is experiencing a transformative shift toward open access, a paradigm that mandates the availability of research outputs such as data, code, materials, and publications. Open access provides increased reproducibility and allows for reuse of these resources. This article provides guidance for best publishing practices of scientific research, data, and associated resources, including code, in The American Phytopathological Society journals. Key areas such as diagnostic assays, experimental design, data sharing, and code deposition are explored in detail. This guidance aligns with that observed by other leading journals. We hope the information assembled in this paper will raise awareness of best practices and enable greater appraisal of the true effects of biological phenomena in plant pathology.


Plant Pathology , Reproducibility of Results , Publishing/standards , Guidelines as Topic , Access to Information , Information Dissemination
4.
Eur Cardiol ; 18: e16, 2023.
Article En | MEDLINE | ID: mdl-37405348

The expansion of the therapeutic armamentarium available to oncologists and haematologists has led to a significant improvement in cancer survival; however, many of the available treatments carry a risk of toxicity to the heart. Cardio-oncology has emerged as a rapidly developing subspeciality dedicated to improving the cardiovascular care of patients before, during and after cancer treatment. The 2022 European Society of Cardiology guidelines on cardio-oncology provide a comprehensive overview of best-practice recommendations for cardiovascular care aimed at healthcare professionals treating cancer patients. The main focus of the guidelines is to ensure patients can complete their cancer treatment without significant cardiotoxicity and the correct follow-up for the first 12 months following treatment and beyond is instituted. The guidelines provide harmonisation of baseline risk stratification and toxicity definitions and encompass recommendations for all the major classes of therapy used in modern oncology and haematology. This review summarises the key points from the guidelines document.

5.
Theor Appl Genet ; 136(7): 154, 2023 Jun 15.
Article En | MEDLINE | ID: mdl-37318664

KEY MESSAGE: Two QTL were identified using linkage mapping approaches, one on hop linkage group 3 (qHl_Chr3.PMR1) associated with powdery mildew resistance and a second on linkage group 10 (cqHl_ChrX.SDR1) associated with sex determination. Hop (Humulus lupulus L.) is a dioecious species cultivated for use in beer. Hop powdery mildew, caused by Podosphaera macularis, is a constraint in many growing regions. Thus, identifying markers associated with powdery mildew resistance and sex provides the opportunity to pyramid R-genes and select female plants as seedlings, respectively. Our objectives were to characterize the genetic basis of R1-mediated resistance in the cultivar Zenith which provides resistance to pathogen races in the US, identify quantitative trait loci (QTL) associated with R1 and sex, and develop markers for molecular breeding-based approaches. Phenotypic evaluation of the population indicated that R1-based resistance and sex are inherited monogenically. We constructed a genetic map using 1339 single nucleotide polymorphisms (SNPs) based upon genotype-by-sequencing of 128 F1 progeny derived from a Zenith × USDA 21058M biparental population. SNPs were assigned to 10 linkage groups comprising a map length of 1204.97 cM with an average density of 0.94 cM/marker. Quantitative trait locus mapping identified qHl_Chr3.PMR1, associated with R1 on linkage group 3 (LOD = 23.57, R2 = 57.2%), and cqHl_ChrX.SDR1, associated with sex on linkage group 10 (LOD = 5.42, R2 = 25.0%). Kompetitive allele-specific PCR (KASP) assays were developed for both QTL and assessed against diverse germplasm. Our results indicate that KASP markers associated with R1 may be limited to materials that are pedigree-related to Zenith, whereas markers associated with sex may be transferable across populations. The high-density map, QTL, and associated KASP markers will enable selecting for sex and R1-mediated resistance in hop.


Humulus , Quantitative Trait Loci , Humulus/genetics , Plant Diseases/genetics , Chromosome Mapping/methods , Genotype , Disease Resistance/genetics
6.
Phytopathology ; 113(10): 1946-1958, 2023 Oct.
Article En | MEDLINE | ID: mdl-37129263

Emergence of pathogens with decreased sensitivity to succinate dehydrogenase inhibitor fungicides is a global agronomical issue. Analysis of Didymella tanaceti isolates (n = 173), which cause tan spot of pyrethrum (Tanacetum cinerariifolium), collected prior to (2004 to 2005) and after (2009, 2010, 2012, and 2014) the commercial implementation of boscalid in Tasmanian pyrethrum fields identified that insensitivity developed over time and has become widespread. To evaluate temporal change, isolates were characterized for frequency of mutations in the succinate dehydrogenase (Sdh) B, C, and D subunits associated with boscalid resistance, mating type, and SSR genotype. All isolates from 2004 and 2005 exhibited wild-type (WT) Sdh alleles. Seven known Sdh substitutions were identified in isolates collected from 2009 to 2014. In 2009, 60.7% had Sdh substitutions associated with boscalid resistance in D. tanaceti. The frequency of WT isolates decreased over time, with no WT isolates identified in 2014. The frequency of the SdhB-H277Y genotype increased from 10.7 to 77.8% between 2009 and 2014. Genotypic evidence suggested that a shift in the population structure occurred between 2005 and 2009, with decreases in gene diversity (uh; 0.51 to 0.34), genotypic evenness (E5; 0.96 to 0.67), genotypic diversity (G; 9.3 to 6.8), and allele frequencies. No evidence was obtained to support the rapid spread of Sdh genotypes by clonal expansion of the population. Thus, insensitivity to boscalid has developed and become widespread within a diverse population within 4 years of usage. These results suggest that D. tanaceti can disperse insensitivity through repeated frequent mutation, sexual recombination, or a combination of both.


Chrysanthemum cinerariifolium , Fungicides, Industrial , Succinic Acid , Succinate Dehydrogenase/genetics , Succinate Dehydrogenase/metabolism , Plant Diseases , Fungicides, Industrial/pharmacology , Succinates , Genetic Structures , Drug Resistance, Fungal/genetics
7.
Plant Dis ; 107(11): 3430-3436, 2023 Nov.
Article En | MEDLINE | ID: mdl-37079010

Pseudoperonospora humuli, causal agent of hop downy mildew, is known to survive winter as systemic mycelium in the crown and developing buds of hop (Humulus lupulus). Field studies were conducted over three growing seasons to quantify the association of infection timing to overwintering of P. humuli and development of downy mildew. Cohorts of potted plants were inoculated sequentially from early summer to autumn, overwintered, and then evaluated for symptoms of systemic downy mildew in emerging shoots. Shoots with systemic P. humuli developed after inoculation at any time in the previous year, with the most severe disease typically resulting from inoculation in August. Independent of the timing of inoculation, diseased shoots emerged coincident with the emergence of healthy shoots, beginning as early as late February and continuing through late May to early June. Surface crown buds on inoculated plants exhibited internal necrosis associated with P. humuli at rates ranging from 0.3 to 1.2%, whereas P. humuli was detected by PCR on 7.8 to 17.0% of asymptomatic buds depending on the timing of inoculation and year. Four experiments were conducted to quantify the impact of foliar fungicides applied in autumn on downy mildew the following spring. There was a small reduction of disease in only one study. Together, these studies indicate that infection by P. humuli that leads to overwintering can occur over a broad period of time, but delaying infection until autumn tends to reduce disease levels in the following year. However, in established plantings, postharvest application of foliar fungicides appeared to have little impact on severity of downy mildew in the ensuring year.


Fungicides, Industrial , Humulus , Oomycetes , Peronospora , Seasons , Fungicides, Industrial/pharmacology , Plant Diseases/prevention & control
11.
Eur J Clin Invest ; 52(11): e13843, 2022 11.
Article En | MEDLINE | ID: mdl-35924957

BACKGROUND: We examined the associations between family income and educational attainment with incident atrial fibrillation (AF), myocardial infarction (MI), stroke and cardiovascular (CV) death among patients with newly-diagnosed heart failure (HF). METHODS: In a nationwide Danish registry of HF patients diagnosed between 2008 and 2018, we established a cohort for each outcome. When examining AF, MI and stroke, respectively, patients with a history of these outcomes at diagnosis of HF were excluded. We used cause-specific proportional hazard models to estimate hazard ratios for tertile groups of family income and three levels of educational attainment. RESULTS: Among 27,947 AF-free patients, we found no association between income or education and incident AF. Among 27,309 MI-free patients, we found that lower income (hazard ratio 1.28 [95% CI 1.11-1.48] and 1.11 [0.96-1.28] for lower and medium vs. higher income) and education (1.23 [1.04-1.45] and 1.15 [0.97-1.36] for lower and medium vs. higher education) were associated with MI. Among 36,801 stroke-free patients, lower income was associated with stroke (1.38 [1.23-1.56] and 1.27 [1.12-1.44] for lower and medium vs. higher income) but not education. Lower income (1.56 [1.46-1.67] and 1.32 [1.23-1.42] for lower and medium vs. higher income) and education (1.20 [1.11-1.29] and 1.07 [0.99-1.15] for lower and medium vs. higher education) were associated with CV death. CONCLUSIONS: In patients with newly-diagnosed HF, lower family income was associated with higher rates of acute MI, stroke and cardiovascular death. Lower educational attainment was associated with higher rates of acute MI and cardiovascular death. There was no evidence of associations between income and education with incident AF.


Atrial Fibrillation , Heart Failure , Myocardial Infarction , Stroke , Atrial Fibrillation/complications , Heart Failure/complications , Heart Failure/epidemiology , Humans , Myocardial Infarction/complications , Myocardial Infarction/epidemiology , Risk Factors , Social Determinants of Health , Stroke/complications , Stroke/epidemiology
12.
J Clin Med ; 11(13)2022 Jun 30.
Article En | MEDLINE | ID: mdl-35807073

BACKGROUND: There is a plethora of real-world data on the safety and effectiveness of direct-acting oral anticoagulants (DOACs); however, study heterogeneity has contributed to inconsistent findings. We compared the effectiveness and safety of apixaban with those of other direct-acting oral anticoagulants (DOACs) and vitamin K antagonists (VKA e.g., warfarin). METHODS: A systematic review and meta-analysis was conducted retrieving data from PubMed, SCOPUS and Web of Science from January 2009 to December 2021. Studies that evaluated apixaban (intervention) prescribed for adults (aged 18 years or older) with AF for stroke prevention compared to other DOACs or VKAs were identified. Primary outcomes included stroke/systemic embolism (SE), all-cause mortality, and major bleeding. Secondary outcomes were intracranial haemorrhage (ICH) and ischaemic stroke. Randomised controlled trials and non-randomised trials were considered for inclusion. RESULTS: In total, 67 studies were included, and 38 studies were meta-analysed. Participants taking apixaban had significantly lower stroke/SE compared to patients taking VKAs (relative risk (RR) 0.77, 95% confidence interval (CI) 0.64-0.93, I2 = 94%) and dabigatran (RR 0.84, 95% CI 0.74-0.95, I2 = 66%), but not to patients administered rivaroxaban. There was no statistical difference in mortality between apixaban and VKAs or apixaban and dabigatran. Compared to patients administered rivaroxaban, participants taking apixaban had lower mortality rates (RR 0.83, 95% CI 0.71-0.96, I2 = 96%). Apixaban was associated with a significantly lower risk of major bleeding compared to VKAs (RR 0.58, 95% CI 0.52-0.65, I2 = 90%), dabigatran (RR 0.79, 95% CI 0.70-0.88, I2 = 78%) and rivaroxaban (RR 0.61, 95% CI 0.53-0.70, I2 = 87%). CONCLUSIONS: Apixaban was associated with a better overall safety and effectiveness profile compared to VKAs and other DOACs.

13.
Adv Simul (Lond) ; 7(1): 13, 2022 May 08.
Article En | MEDLINE | ID: mdl-35527267

Simulation-based procedure training is now integrated within health professions education with literature demonstrating increased performance and translational patient-level outcomes. The focus of published work has been centered around description of such procedural training and the creation of realistic part-task models. There has been little attention with regards to design consideration, specifically around how simulation and educational theory should directly inform programme creation. Using a case-based approach in cardiology as an example, we present a blueprint for theory-informed simulation-based procedure training linking learning needs analysis and defining suitable objectives to matched fidelity. We press the importance of understanding how to implement and utilise task competence benchmarking in practice, and the role of feedback and debriefing in cycles of repeated practice. We conclude with evaluation and argue why this should be considered part of the initial design process rather than an after-thought following education delivery.

14.
Plant Dis ; 106(10): 2601-2606, 2022 Oct.
Article En | MEDLINE | ID: mdl-35486600

Fusarium sambucinum is an ascomycete that has been isolated from a broad range of plant hosts, including hop (Humulus lupulus L.), where it acts as a causal agent of Fusarium canker, a disease that can impact cone quality and yield in severe cases. Current diagnostic methods rely on isolation of the fungus from plant tissue, a time- and resource-intensive process with limited sensitivity, complicated by the potential presence of other Fusarium spp. that have been reported on hop. Our objective was to develop a rapid and sensitive diagnostic tool to detect and quantify F. sambucinum in plant tissues. Using a modified random amplified polymorphic DNA PCR assay, we identified a F. sambucinum-specific marker that serves as the target in a TaqMan (hydrolysis) probe quantitative PCR (qPCR) assay that can be used to detect F. sambucinum DNA in a background of plant DNA. When used to screen 52 isolates of F. sambucinum and isolates representing 13 other Fusarium spp., the assay was robust in detecting F. sambucinum while discriminating between F. sambucinum and closely related Fusarium spp., including F. venenatum. Furthermore, this assay reliably detects as little as 1 pg of F. sambucinum DNA in a background of total DNA from plant tissue. Within-sample comparisons of this qPCR assay with traditional cultural isolation methods demonstrated the greater sensitivity of the qPCR-based method for detection of F. sambucinum. When used to screen 220 asymptomatic stem samples, the qPCR assay detected F. sambucinum in 100 samples (45.5%); by comparison, F. sambucinum was detected in only 3 samples (1.4%) by culturing methods. Moreover, quantification of F. sambucinum DNA was possible for 60 of these samples, indicating the utility of the qPCR assay for early detection. This assay should be useful in diagnostic and epidemiological applications to detect and quantify F. sambucinum from multiple hosts and environmental samples.


Fusarium , DNA, Fungal/analysis , DNA, Fungal/genetics , DNA, Plant , Fusarium/genetics , Real-Time Polymerase Chain Reaction
15.
J Eur CME ; 11(1): 2055266, 2022.
Article En | MEDLINE | ID: mdl-35340895

The European Examination in Core Cardiology (EECC) is a knowledge-based postgraduate examination for cardiology specialists in Europe. It is designed to assess if a trainee has gained sufficient knowledge for independent specialist practice in core cardiology. A critical evaluation of the ECCC was undertaken using current educational theory. Miller's Pyramid was considered, and the Utility Equation was employed in a mixed methods approach. The utility analysis findings were that the EECC measured well on reliability and validity although improvement could be made in educational impact, cost-effectiveness and accessibility. Recommendations for enhancement were then put forward. No assessment instrument is perfect, and it is important to remember that the EECC is one component of assessment strategy for specialist trainees, complementing other evidence of professional competence. After appraisal, while improvement can be made, the EECC fulfils its ambitions of assessment.

16.
Plant Dis ; 106(6): 1681-1689, 2022 Jun.
Article En | MEDLINE | ID: mdl-34978868

The hop cultivar 'Cascade' possesses partial resistance to powdery mildew (Podosphaera macularis) that can be overcome by recently emerged, virulent isolates of the fungus. Given that hop is a long-lived perennial and that brewers still demand Cascade, there is a need to better understand factors that influence the development of powdery mildew on this cultivar. Growth chamber experiments were conducted to quantify the effect of constant, transient, and fluctuating temperature on Cascade before, concurrent to, and after inoculation as contrasted with another powdery mildew-susceptible cultivar, 'Symphony'. Exposure of plants to supraoptimal temperature (26 and 32°C) before inoculation led to more rapid onset of ontogenic resistance in intermediately aged leaves in Cascade as compared with Symphony. Cascade was overall less susceptible to powdery mildew when exposed to constant temperature ranging from 18 to 32°C directly after inoculation. However, cultivar also interacted with temperature such that proportionately fewer and smaller colonies developed on Cascade than Symphony at supraoptimal yet permissive temperatures for disease. When plants were inoculated and then exposed to high temperature, colonies became progressively more tolerant to temperatures of 26 to 30°C with increasing time from inoculation to exposure, as moderated by cultivar, the specific temperature, and their interaction. Subjecting plants to simulated diurnal temperature regimes at the time of inoculation or 24 h later indicated Cascade and Symphony responded proportionately similarly on days predicted to be marginally unfavorable or marginally favorable for powdery mildew, although Cascade was quantitatively less susceptible than Symphony. In sum, this research indicates that Cascade is overall less susceptible to powdery mildew than Symphony, and supraoptimal temperature before, concurrent to, or after infection may interact differentially to moderate disease risk in Cascade. Therefore, cultivar-specific risk assessments for powdery mildew appear warranted.


Plant Diseases , Plant Leaves , Plant Diseases/microbiology , Plant Leaves/microbiology , Temperature
17.
Plant Dis ; 106(4): 1244-1252, 2022 Apr.
Article En | MEDLINE | ID: mdl-34818909

Understanding of the physical mode of action of fungicides allows more efficient and effective application and can increase disease control. Greenhouse and field studies were conducted to explore the preinfection and postinfection duration and translocative properties of fungicides commonly used to control hop powdery mildew, caused by Podosphaera macularis. In greenhouse studies, applications made 24 h before inoculation were almost 100% effective at suppressing powdery mildew, regardless of the fungicide evaluated. However, percentage control of powdery mildew based on the number of pathogen colonies per leaf varied significantly between fungicides with increasing time from inoculation to application, ranging from 50 to 100% disease control depending on the fungicide. Fluopyram or fluopyram + trifloxystrobin was particularly efficacious, suppressing nearly all powdery mildew development independent of application timing. In translocation studies, fluopyram and flutriafol were the most effective treatments in each of two separate experiments, resulting in zones of inhibition of 1,036 and 246.3 mm2, respectively, on adaxial leaf surfaces when a single droplet of each fungicide was applied to the abaxial surface of leaves. In field experiments, all fungicide treatments provided nearly complete control of powdery mildew infection when applied before inoculation. Levels of disease control decreased with time depending on treatment, showing trends similar to those observed in greenhouse studies. In the 2017 field experiments, high levels of disease control (>75%) were observed at postinoculation time points for all treatments tested, whereas the same fungicides were more sensitive to application timing in a different year. Findings from this research indicate that differences in efficacy between fungicides are small when applications are made preventively, but postinfection activity and translaminar movement of certain fungicides may render some more effective depending on application coverage and preexisting infection.


Fungicides, Industrial , Fungicides, Industrial/pharmacology , Plant Diseases/prevention & control , Plant Leaves
18.
Case Rep Oncol ; 15(3): 950-959, 2022.
Article En | MEDLINE | ID: mdl-36636681

Trabectedin is a chemotherapeutic used to treat advanced soft tissue sarcoma and relapsed platinum-sensitive ovarian cancer. Although it is associated with a low incidence of cardiotoxicity, when this occurs it can be fatal or significantly compromise the quality of life in patients with advanced cancer. Here, we present a series of 4 cases where trabectedin-treated sarcoma patients developed cardiovascular complications. Similar to previous literature describing this association, all patients had prior treatment with anthracyclines and presented at different time points following treatment initiation. Each patient presented with exertional breathlessness and was found to have severely impaired left ventricular systolic function (ejection fraction ≤35%), and 1 patient had concurrent atrial fibrillation with a fast ventricular rate. All of the patients were treated with neurohormonal blockade, and a multi-disciplinary decision was made to stop trabectedin in 3 patients and continue in 1 patient. Two of the 4 patients had an improvement in their left ventricular systolic function. It is unclear what effect preceeding anthracycline or tyrosine kinase inhibitor treatment has in priming patients to develop cardiotoxicity in this setting. Our case series adds to the evidence surrounding this association and highlights that trabectedin-associated cardiotoxicity can present in an insidious fashion.

19.
Mol Plant Pathol ; 22(7): 755-768, 2021 07.
Article En | MEDLINE | ID: mdl-33942461

Pseudoperonospora humuli is an obligate biotrophic oomycete that causes downy mildew, one of the most devastating diseases of cultivated hop, Humulus lupulus. Downy mildew occurs in all production areas of the crop in the Northern Hemisphere and Argentina. The pathogen overwinters in hop crowns and roots, and causes considerable crop loss. Downy mildew is managed by sanitation practices, planting of resistant cultivars, and fungicide applications. However, the scarcity of sources of host resistance and fungicide resistance in pathogen populations complicates disease management. This review summarizes the current knowledge on the symptoms of the disease, life cycle, virulence factors, and management of hop downy mildew, including various forecasting systems available in the world. Additionally, recent developments in genomics and effector discovery, and the future prospects of using such resources in successful disease management are also discussed. TAXONOMY: Class: Oomycota; Order: Peronosporales; Family: Peronosporaceae; Genus: Pseudoperonospora; Species: Pseudoperonospora humuli. DISEASE SYMPTOMS: The disease is characterized by systemically infected chlorotic shoots called "spikes". Leaf symptoms and signs include angular chlorotic lesions and profuse sporulation on the abaxial side of the leaf. Under severe disease pressure, dark brown discolouration or lesions are observed on cones. Infected crowns have brown to black streaks when cut open. Cultivars highly susceptible to crown rot may die at this phase of the disease cycle without producing shoots. However, foliar symptoms may not be present on plants with systemically infected root systems. INFECTION PROCESS: Pathogen mycelium overwinters in buds and crowns, and emerges on infected shoots in spring. Profuse sporulation occurs on infected tissues and sporangia are released and dispersed by air currents. Under favourable conditions, sporangia germinate and produce biflagellate zoospores that infect healthy tissue, thus perpetuating the infection cycle. Though oospores are produced in infected tissues, their role in the infection cycle is not defined. CONTROL: Downy mildew on hop is managed by a combination of sanitation practices and timely fungicide applications. Forecasting systems are used to time fungicide applications for successful management of the disease. USEFUL WEBSITES: https://content.ces.ncsu.edu/hop-downy-mildew (North Carolina State University disease factsheet), https://www.canr.msu.edu/resources/michigan-hop-management-guide (Michigan Hop Management Guide), http://uspest.org/risk/models (Oregon State University Integrated Plant Protection Center degree-day model for hop downy mildew), https://www.usahops.org/cabinet/data/Field-Guide.pdf (Field Guide for Integrated Pest Management in Hops).


Humulus/parasitology , Oomycetes/physiology , Plant Diseases/parasitology , Disease Resistance , Fungicides, Industrial , Humulus/immunology , Plant Diseases/immunology , Plant Diseases/prevention & control
20.
Phytopathology ; 111(11): 1972-1982, 2021 Nov.
Article En | MEDLINE | ID: mdl-33829855

Hop powdery mildew, caused by the ascomycete fungus Podosphaera macularis, is a consistent threat to sustainable hop production. The pathogen utilizes two reproductive strategies for overwintering and perennation: (i) asexual vegetative hyphae on dormant buds that emerge the following season as infected shoots; and (ii) sexual ascocarps (chasmothecia), which are discharged during spring rain events. We demonstrate that P. macularis chasmothecia, in the absence of any asexual P. macularis growth forms, are a viable overwintering source capable of causing early season infection two to three orders of magnitude greater than that reported for perennation via asexual growth. Two epidemiological models were defined that describe (i) temperature-driven maturation of P. macularis chasmothecia; and (ii) ascosporic discharge in response to duration of leaf wetness and prevailing temperatures. P. macularis ascospores were confirmed to be infectious at temperatures ranging from 5 to 20°C. The organism's chasmothecia were also found to adhere tightly to the host tissue on which they formed, suggesting that these structures likely overwinter wherever hop tissue senesces within a hop yard. These observations suggest that existing early season disease management practices are especially crucial to controlling hop powdery mildew in the presence of P. macularis chasmothecia. Furthermore, these insights provide a baseline for the validation of weather-driven models describing maturation and release of P. macularis ascospores, models that can eventually be incorporated into hop disease management programs.


Ascomycota , Humulus , Plant Diseases/microbiology , Ascomycota/pathogenicity , Humulus/microbiology
...