The Role of Ascospores and Conidia as Propagules in the Disease Cycle ofHypoxylon mammatum

1992 ◽  
Vol 82 (1) ◽  
pp. 114 ◽  
Author(s):  
David H. Griffin
Keyword(s):  
Disease Cycle

scholarly journals Detection, Distribution, Sporulation, and Survival of Phytophthora ramorum in a California Redwood-Tanoak Forest Soil

2007 ◽  
Vol 97 (10) ◽  
pp. 1366-1375 ◽  
Author(s):  
E. J. Fichtner ◽  
S. C. Lynch ◽  
D. M. Rizzo
Keyword(s):  
Phytophthora Ramorum ◽  
Disease Cycle ◽  
Soil Baiting ◽  
Umbellularia Californica ◽  
Lithocarpus Densiflorus ◽  
Important Host ◽  
The Impact ◽  
Soil Interface ◽  
Leaf Disks

Recovery of Phytophthora ramorum from soils throughout sudden oak death-affected regions of California illustrates that soil may serve as an inoculum reservoir, but the role of soil inoculum in the disease cycle is unknown. This study addresses the efficacy of soil baiting, seasonal pathogen distribution under several epidemiologically important host species, summer survival and chlamydospore production in soil, and the impact of soil drying on pathogen survival. The efficacy of rhododendron leaves and pears as baits for detection of soilborne propagules were compared. Natural inoculum associated with bay laurel (Umbellularia californica), tanoak (Lithocarpus densiflorus), and redwood (Sequoia sempervirens) were determined by monthly baiting. Summer survival and chlamydospore production were assessed in infected rhododendron leaf disks incubated under bay laurel, tanoak, and redwood at either the surface, the litter/soil interface, or in soil. Rhododendron leaf baits were superior to pear baits for sporangia detection, but neither bait detected chlamydospores. Most inoculum was associated with bay laurel and recovery was higher in soil than litter. Soil-incubated inoculum exhibited over 60% survival at the end of summer and also supported elevated chlamydospore production. P. ramorum survives and produces chlamydospores in forest soils over summer, providing a possible inoculum reservoir at the onset of the fall disease cycle.

The Role of Flowers in the Disease Cycle of Colletotrichum fioriniae and Other Cranberry Fruit Rot Fungi

2020 ◽  
Vol 110 (7) ◽  
pp. 1270-1279
Author(s):  
Timothy J. Waller ◽  
J. Gager ◽  
Christine Constantelos ◽  
Peter V. Oudemans
Keyword(s):  
Plant Pathogens ◽  
Growing Season ◽  
Growth Patterns ◽  
Fruit Rot ◽  
Plant Canopy ◽  
Appressorium Formation ◽  
Disease Cycle ◽  
Colletotrichum Spp ◽  
Latent Pathogens

Floral extracts (FEs) can influence the infectivity and epidemiology of fruit infecting Colletotrichum species. In this study, Colletotrichum fioriniae responded to cranberry FEs with an increased rate and magnitude of secondary conidiation and appressorium formation. Four other cranberry fruit rotting species also showed an increased rate of germination in the presence of FEs. However, increased appressorium formation was observed only in the latent pathogens Coleophoma cylindrospora, Colletotrichum fructivorum, and Colletotrichum fioriniae. Two other fruit rotting species, Phyllosticta vaccinii and Allantophomopsis lycopodina, did not form appressoria while secondary conidiation was only seen with the Colletotrichum spp. When conidia of Colletotrichum fioriniae were inoculated in the presence of FE, the incidence of disease was greater on cranberry fruit. Conidia of this species also formed appressoria at lower than expected temperatures in the presence of FE. Dissection of the flowers revealed that the corolla (with stamens and stigma) was the most stimulatory part of the inflorescence. These observations suggest an important and ephemeral role of flowers in the epidemiology of fruit rot. Stimulatory floral signals were readily detected using a conidial germination bioassay and rainwater samples collected from the plant canopy throughout the growing season confirmed that bioactivity was highest during the bloom period, and declined as the fruit developed. The data presented show that floral signals can alter the growth patterns of a larger than previously observed range of fungi and the mobility of floral signals within the canopy implicates these phenology-specific cues in modifying the disease cycles of numerous plant pathogens.

scholarly journals Spinach Downy Mildew: Advances in Our Understanding of the Disease Cycle and Prospects for Disease Management

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 791-803 ◽  
Author(s):  
Shyam L. Kandel ◽  
Beiquan Mou ◽  
Nina Shishkoff ◽  
Ainong Shi ◽  
Krishna V. Subbarao ◽  
...  
Keyword(s):  
Disease Management ◽  
Downy Mildew ◽  
Management Strategies ◽  
Organic Production ◽  
Disease Cycle ◽  
The Past ◽  
Sexual Recombination ◽  
Oomycete Pathogen ◽  
Spinach Downy Mildew

Downy mildew on spinach is caused by Peronospora effusa, an oomycete pathogen that poses a challenge to spinach production worldwide, especially in organic production. Following infection, P. effusa produces abundant amounts of asexual sporangia. Sporangia become windborne and initiate new infections locally or distantly, leading to widespread epidemics. Oospores produced from the union of opposite mating types have been observed within infected leaves and seeds and may remain viable for many years. Sexual reproduction increases the genetic diversity of P. effusa through sexual recombination, and thus, the movement of oospores on seed has likely fueled the rapid explosion of new pathotypes in different regions of the world over the past 20 years. This review summarizes recent advances in spinach downy mildew research, especially in light of the findings of oospores in contemporary commercial spinach seed lots as well as their germination. Knowledge of the role of the oospores and other aspects of the disease cycle can directly translate into new and effective disease management strategies.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

Refining our understanding of the “elephant in the room”

2020 ◽  
Vol 43 ◽  
Author(s):  
Andrew Whiten
Keyword(s):  
Social Cognition ◽  
Cultural Evolution ◽  
Cognitive Abilities ◽  
Critical Factors ◽  
Technological Culture

Abstract The authors do the field of cultural evolution a service by exploring the role of non-social cognition in human cumulative technological culture, truly neglected in comparison with socio-cognitive abilities frequently assumed to be the primary drivers. Some specifics of their delineation of the critical factors are problematic, however. I highlight recent chimpanzee–human comparative findings that should help refine such analyses.

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