disease cycle
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2021 ◽  
Author(s):  
Franklin Jackson Machado ◽  
Aline Vieira Barros ◽  
Nicole McMaster ◽  
David Schmale ◽  
Lisa J. Vaillancourt ◽  
...  

Fusarium meridionale and F. graminearum both cause Gibberella ear (GER) and stalk rot (GSR) of maize in Brazil, but the former is much more common. Recent work with two isolates of each from maize suggested this dominance could be due to greater aggressiveness and competitiveness of F. meridionale on maize. We evaluated pathogenicity and toxigenicity of 16 isolates of F. graminearum and 24 isolates of F. meridionale recovered from both wheat and maize. Strains were individually inoculated into ears of four maize hybrids in field trials. GER severity varied significantly among isolates within each species. Although ranges overlapped, the average GER severity induced by F. meridionale (25.2%) was two times higher overall than F. graminearum (12.8%) for isolates obtained from maize, but similar for those isolated from wheat (19.9 and 21.4% respectively). In contrast, severity of GSR was slightly higher for F. graminearum (22.2%) versus F. meridionale (19.8%), with no effect of the host of origin. Deoxynivalenol and its acetylated form 15ADON were the main mycotoxins produced by F. graminearum (7/16 strains), while nivalenol toxin was produced by F. meridionale (17/24 strains). Six isolates of F. graminearum and three of F. meridionale also produced zearalenone. Results confirmed that F. meridionale from maize is, on average, more aggressive on maize, but also suggested greater complexity related to diversity among the individual isolates within each species and their interactions with different hybrids. Further studies involving other components of the disease cycle are needed to more fully explain observed patterns of host dominance


2021 ◽  
Author(s):  
Franklin Jackson Machado ◽  
Aline Vieira de Barros ◽  
Nicole McMaster ◽  
David G. Schmale ◽  
Lisa J. Vaillancourt ◽  
...  

Gibberella ear (GER) and stalk rot (GSR) of maize in Brazil are caused mainly by Fusarium meridionale, while F. graminearum is the more common cause of Fusarium Head Blight (FHB) on wheat. Our previous study of two maize isolates of each species suggested that this pattern of dominance may be due to greater aggressiveness and competitiveness of F. meridionale on maize. Here we have evaluated pathogenicity and toxigenicity of 16 isolates of F. graminearum and 24 isolates of F. meridionale recovered from both wheat and maize. Strains were individually inoculated into ears of four maize hybrids in field trials. GER severity varied significantly among isolates within each species. Although ranges overlapped, average GER severity induced by F. meridionale (13.9%) was two times higher than F. graminearum (7.2%) for isolates obtained from maize, but similar for those isolated from wheat (11.8 and 10.6% respectively). In contrast, severity of GSR was slightly numerically higher for F. graminearum (18.4%) versus F. meridionale (16.1%), with no effect of host of origin. Deoxynivalenol (DON) and its acetylated form 15ADON were the main mycotoxins produced by F. graminearum (7/16 strains), while nivalenol (NIV) was the only toxin produced by F. meridionale (17/24 strains). Six isolates of F. graminearum also produced zearalenone. Results confirm that F. meridionale from maize is, on average, more aggressive on maize, but suggest greater complexity related to diversity among individual isolates within each species. Further studies involving other components of the disease cycle may help to more fully explain the observed pattern of host dominance.


EDIS ◽  
2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Camille McAvoy ◽  
Pamela Roberts ◽  
Jeffrey B. Jones

Bacterial spot, caused by three species of Xanthomonas, is a limiting disease problem on all peppers. This new 4-page fact sheet provides information on symptoms, causal organism and host resistance, disease cycle and epidemiology, and disease management (including cultural and sanitation practices, chemical control measures and the use of Actigard® in chile peppers). Written by Camille McAvoy, Pamela Roberts, and Jeffrey Jones, and published by the UF/IFAS Plant Pathology Department.https://edis.ifas.ufl.edu/pp362


2021 ◽  
pp. 353-373
Author(s):  
Govind Singh Saharan ◽  
Naresh K. Mehta ◽  
Prabhu Dayal Meena
Keyword(s):  

2021 ◽  
pp. 9-48
Author(s):  
Shou-Hua Wang

Abstract This chapter focuses on the concept of plant disease, which is a condition where plant tissue or growth is damaged or altered by a pathogen or environmental factors. Information is also given on the interactions between the host plant, pathogen(s) and environmental factors (disease triangle), symptomatology, types of plant diseases, transmission, disease cycle and plant pathogens (fungi, bacteria, viruses and nematodes) and their control.


The toxoplasmosis is a zoonosis caused by protozoan Toxoplasma Gondii and although cats play a main roll on the disease life cycle developing the protozoan by sexual reproduction, the contact with cats represents a low number of cases on transmission of the zoonosis, the main transmission is caused by the intake of infected food, like fruits, vegetables, raw or poorly cooked meat that may contain cysts. The study was developed aiming to evaluate the knowledge and preventive behavior regarding toxoplasmosis and link it with cats on the cycle of the zoonosis. A form was created with eight questions about it, 793 people participated, all located in national territory. Therefore, based on this information, we can confirm that, although most of the people that already have a college degree or is still finishing it, does not have knowledge about toxoplasmosis, whereas the majority still think that contact with cats is the biggest way to become infected.


2021 ◽  
pp. 343-376
Author(s):  
Lynn E. Long ◽  
Gregory A. Lang ◽  
Clive Kaiser

Abstract This chapter provides information on the various pathogens causing damage to cherry production, such as Pseudomonas syringae pv. syringae, Podosphaera clandestina, Chondrostereum purpureum and Little cherry virus 1 and 2, among others. Details on their symptoms, transmission and disease cycle are discussed and the efficacy of various methods in their management are pointed out.


2020 ◽  
Vol 110 (7) ◽  
pp. 1270-1279
Author(s):  
Timothy J. Waller ◽  
J. Gager ◽  
Christine Constantelos ◽  
Peter V. Oudemans

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.


Author(s):  
N. V. Manashchuk ◽  
◽  
N. V. Chorny ◽  
S. I. Boytsanyuk ◽  
А. V. Chorny ◽  
...  

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