This document discusses key concepts in plant disease epidemiology. It defines epidemics as widespread disease affecting many individuals over a large area in a short time. Endemic diseases constantly occur year after year, while pandemics involve mass mortality over continents. Sporadic diseases occur irregularly over limited areas. Epidemics follow disease progress curves from an initial destructive phase to a decline phase. They are influenced by factors like the pathogen, host, environment, and human activities. The interaction of these factors forms the basis of disease triangles and tetrahedrons.
In this slide you will get all the important information of epidemiology.
For more information you can see my youtube channel
https://www.youtube.com/channel/UCUsmJMc2xvL3O3UkDh8knrA
Effect of environment and nutrition on plant disease developmentparnavi kadam
BRIEF AND PRECISE POINTS ON PLANT DISEASE DEVELOPMENT. IT MOSTLY FOCUSES ON HOW THE FACTORS AFFECT THE MICROBES AND THEN THEIR MICROBIAL EFFECT ON DISEASE DEVELOPMENT.
In this slide you will get all the important information of epidemiology.
For more information you can see my youtube channel
https://www.youtube.com/channel/UCUsmJMc2xvL3O3UkDh8knrA
Effect of environment and nutrition on plant disease developmentparnavi kadam
BRIEF AND PRECISE POINTS ON PLANT DISEASE DEVELOPMENT. IT MOSTLY FOCUSES ON HOW THE FACTORS AFFECT THE MICROBES AND THEN THEIR MICROBIAL EFFECT ON DISEASE DEVELOPMENT.
Introduction to the science of plant pathology, its objectives, scope and historical background. Classification of plant diseases, symptoms, signs, and related terminology. Parasitic causes of plant diseases (fungi, bacteria, viruses, phytoplasma, protozoa, algae and flowering parasitic plants), their characteristics and classification. Non-parasitic causes of plant diseases. Infection process. Survival and dispersal of plant pathogens. Plant disease epidemiology, forecasting and disease assessment. Principles and methods of plant disease management. Integrated plant disease management.
Introduction to the science of plant pathology, its objectives, scope and historical background. Classification of plant diseases, symptoms, signs, and related terminology. Parasitic causes of plant diseases (fungi, bacteria, viruses, phytoplasma, protozoa, algae and flowering parasitic plants), their characteristics and classification. Non-parasitic causes of plant diseases. Infection process. Survival and dispersal of plant pathogens. Plant disease epidemiology, forecasting and disease assessment. Principles and methods of plant disease management. Integrated plant disease management.
Epidemiology and Forecasting of plant disease
Monocyclic and Polycyclic
Disease progressive curve
How the Plant Affects Development of Epidemics.
Environmental factors.
Measuring Disease in a Population
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
3. Epidemics
When a pathogen spreads to and affects many
individuals within a population over a relatively large
area and within a relatively short time, the
phenomenon is called an epidemic
Any increase of disease in a population
the dynamics of change in plant disease in time and
space
4. Endemic
When a disease is more or less constantly occurring
year after year in a moderate to severe form in a
country or locality then it is called as endemic disease.
e.g.: wart disease of potato (Synchytrium
endobioticum) is endemic in Darjeeling, citrus canker
(Xanthomonas axonopodis pv citri)in Asia and
sorghum rust (Puccinia purpurea).
5. Pandemic
When an epidemic disease spreads over continents or
subcontinents and involves mass mortality it is
considered as pandemic.
The outbreak of black stem rust of wheat in India
during 1947 is best example for a pandemic disease.
6. Sporadic
Diseases which occur at irregular intervals over limited
areas or locations are called sporadic.
They occur relatively in few instances.
e.g.: Fusarium wilt of cotton (Fusarium oxysporum f
sp. vasiinfectum) grain smut of sorghum (Sporisorium
sorghi ) and loose smut of wheat (Ustilago nuda).
7. Course of Epidemic
Two phases
Progressively destructive phase
The decline phase
8. Epidemic types
Slow epidemic (Tardive epidemic)
Occurs in monocyclic diseases
On perennial plants
E.g. citrus tristeza; Dutch elm disease
Fast epidemic (Explosive epidemic)
In polycyclic diseases
Annual crops
E.g. rice blast, potato blight
9. Epidemiology
Epidemiology can be defined as the study of population of
pathogen in the population of host and the resulting disease
under the influence of environmental and human factors
The study of epidemics and of the factors that influence
them
Epidemiology is concerned simultaneously
Populations of pathogens
Host plants
Environment
These three can be depicted in the form of a disease triangle
11. Epidemics of past
The Irish potato famine of 1845–1846 was caused by
the Phytophthora late blight epidemic of potato,
The Bengal famine of 1943 was caused by the
Cochliobolus (Helminthosporium) brown spot
epidemic of rice.
12. Elements of an Epidemic
In fungal & bacterial diseases:
The susceptible Host
The virulent Pathogen
favorable environmental conditions
Human activity
These four can be depicted in the form of a disease
tetrahedron
In virus & virus like diseases
The Virus
The Host
The Vector
Environment
15. Host Factors
Pathogen Factors
Environmental Factors
Effect of Human Cultural Practices and Control
Measures (Human Activities)
Time factors
Factors
16. Schematic diagram of the interrelationships of
the factors involved in plant disease epidemics.
17. Host Factors
Level of genetic resistance or susceptibility of host
Degree of Genetic Uniformity of Host Plants
Type of Crop
Age of Host Plants
Population Density and Structure
General Plant Health
Introduction of New Host
Introduction of New Alternate Host
18. Level of Genetic Resistance or Susceptibility of
Host
Highly resistant.
Moderately resistant.
Susceptible.
Vertical resistance.(Monogenic, Host specific).
Horizontal resistance.(Polygenic, More durable).
19. Development of Cylindrocladium black rot, caused by the fungus C.
crotalariae, on susceptible (Florigiant), resistant (NC3033), and
intermediate peanut varieties. The various genotypes maintain their
resistance rankings in both years (1986, 1987) and at all inoculum
density levels tested. [From Culbreath et al. (1991).]
20. Degree of Genetic Uniformity of Host Plant
Monoculture (more likely hood).
New strains are developed.
e.g. Cochliobolus blight on Victoria oats,
And in southern corn leaf blight on corn carrying Texas male
sterile cytoplasm.
Rate of epidemic in response of genetic uniformity (Vegetative
grafting, self pollinated, cross pollinated hosts)
21. Types of Crops
Annual crops.
Biennial
Perennial crops.
Annual crops & foliar or fruits diseases develop much more
rapidly (in weeks).
Perennial woody diseases take longer time to develop (in
years)
22. Age of Host Plant
Plants change it resistance and susceptibility with age.
Some plants are susceptible only during growth period & become
resistant during mature period.
The change of resistance with age is known as ontogenic resistance.
Pythium damping off and root rots, downy mildews, peach leaf curl,
systemic smuts, rusts, bacterial blights, and viral infections, the
hosts (or their parts) are susceptible only during the growth period
and become resistant during the adult period (adult resistance)
23. Change of susceptibility of plant parts with age
Change of susceptibility of plant parts with age.
In pattern I, plants are susceptible only in the stages of
maximum growth (Ia) or in the earliest stages of growth (Ib).
In pattern II, plants are susceptible only after they reach
maturity, and susceptibility increases with senescence.
In pattern III, plants are susceptible while very young and
again after they reach maturity.
24. Effect of crop age on rate of infection. Cassava plantings of different ages
exposed to the whitefly-transmitted African cassava mosaic geminivirus
show increased resistance to infection as they age. [From Fargette and
Vie (1994). Phytopathology 84, 378–382.]
25. Population Density and Structure
A Large Number of Host to the Pathogen
A Large Area to Reproduce
General Plant Health
Introduction of Alternate Host
• Weaker the plant disease will be more
• Source of Primary Inoculum to the Next Crop
• Determine the Course and Intensity of an Epidemic
26. Pathogen Factors
Presence of Pathogen
Levels of Virulence
Quantity of Inoculums Near Hosts
Type of Reproduction of The Pathogen
Ecology of The Pathogen
Mode of Spread of the Pathogen
Introduction of New Pathogen
High birth and Low Death rate
Adaptability
27. Levels of Virulence
Highly aggressive
High level of virulence more inoculum
Disease epidemic faster
Phytopthora infestans cause late blight of potatoes
Moderately aggressive (disease spread moderately)
Poorly aggressive
Lesser inoculum
disease spread in several years
Xanthomonas axonopodis cause citrus canker
28. Quantity of Inoculums Near Hosts
Greater the number of propagules greater will be the
rate of disease
Greater the inoculum greater will be the disease
Inoculum is less in quantity then the disease never
occurs
29. Effect of amount of soil
inoculum of Verticillium
dahliae on the amount of
vascular wilt on potato
plants at various dates
after planting. Disease is
expressed as a percentage
of stems (A)
and of main vascular
bundles (B) infected at the
base of the plants. , no
pathogen detected; , 1–5
propagules per gram (ppg);
, 6–10 ppg; and , more than
10 ppg. [From Nicot and
Rouse (1987).
Phytopathology 77, 1346–
1355.]
30. Type of Reproduction of The Pathogen
Based on reproductive cycle
Polycyclic
Cause severe epidemics
Produce many generations in a single growing season
More inoculum production
Monocyclic
Takes many of years to develop in epidemic form (polyetic)
Produce only one generation in a year
complete only one life cycle in one year or growing season
Based on type of reproduction
Sexual (oospores, ascospores)
Asexual (conidia, zoospores)
31. Schematic representation of a polyetic epidemic caused in a crop in a
field by a soil pathogen over a 4-year period.
32. Ecology of The Pathogen
Depends on the type of pathogen
Ectoparasites
Inoculum produce on the aerial parts of the host.
Spores and seeds disperse with ease over a range of distances and
cause epidemics.
Endoparasites
Pathogen can be systemic in nature produce inoculum in the
system of host
Spread of pathogen is rare without vectors
33. Mode of Spread of the Pathogen
Survival Efficiency
Air-borne
Soil-borne
Vector-borne
Dispersal Efficiency
Passive dispersal (may be in Km)
Field tools and instruments
Air
Wind
Irrigation Water
Soil (etc)
Active dispersal (may be in cm)
35. Large field of lettuce heads killed by infections with airborne
ascospores of the same fungus
36. Environmental Factors
Aerial environment
Edaphic Environment
Some other factors
Wind
Air pollution
Herbicide damage
37. Aerial environment
Temperature
Affects disease cycles of pathogens
Can prolonged or shorten the disease cycle
Moisture(Dominant factor in diseases caused by
oomycetes, fungi, bacteria & nematodes)
Rainfall (duration and intensity)
Dew (duration and intensity)
Leaf wetness period
38. Edaphic Environment
Concern with soil environment
Soil temperature
Soil pH
Soil water content
Soil fertility
Soil organic matter content
39. Human Activities
Have direct or indirect effect on disease epidemics.
Favorable and unfavorable for disease epidemic
Some of them are:
Site selection and preparation.
Selection of propagative material.
Culture practices.
Disease control measures.
Introduction of new pathogen.
40. Site Selection and Preparation
The following types of soil or fields are favorable for the
development of epidemics;
Low lying soil.
Poorly drained soil.
Poorly aerated field.
Field near the infected field
41. Selection of Propagative Material
Diseased propagative materials
Use of infected seed
Infected nursery stock
Infected root stock and scion
Diseased suckers
Diseased cuttings
42. Cultural Practices
Cultural practices that increase the possibility and
severity of epidemics, are:
Continuous monoculturing.
Higher degree of uniformity.
No-till culture.
Dense planting.
Overhead irrigation.
Injury by herbicide application.
Poor sanitation.
43. Effect of foliage density on development of Phytophthora infestans
during a period of partly favorable weather (May–June) and of
very favorable weather (November–December).
[From Rotem and Ben-Joseph (1970). Plant Dis. Rep. 54, 768–771.]
44. Disease Control Measures
Some practices reduce or eliminate the possibility of an
epidemic, these may be:
Chemical spray.
Cultural practices.(Sanitation, Crop rotation etc.)
Biological control.
Use of resistant varieties.
And some other control measures.
Sometime certain control may develop virulent strain.
These strain are:
Either resistant to chemicals.
Or can overcome the resistant of varieties.
These control measures are:
Excessive use of chemicals against pathogens.
Monoculturing for a long time on large area.
45. Introduction of New Pathogen
Possibility of introducing new pathogen
Transportation of planting materials (seed, nursery
stock, tubers, cuttings, etc) and agricultural goods.
Inability to produce resistance against new
pathogen.(Dainge in case of human)
Pathogens cause severe epidemics.
For example: chestnut blight, Dutch elm disease and
citrus canker caused by Xanthomonas compestris pv.
citri.
46. Time factors
Season of the year
Duration & frequency of favorable temp. & rains
Appearance of vectors, etc.
47. Measurement of Plant Disease and Yield Loss
Disease incidence
The number of plant units that are diseased in relation to
The total number of units examined
Commonly used to measure the spread of a disease
Disease severity
The amount of plant tissue that is diseased
Measured using assessment scales or by determining the
Area under a disease progress curve (AUDPC)
Yield loss
The proportion of yield that the grower will not be able to
harvest due to disease
Results in economic loss
48. Pattern of Epidemics
Interactions among the elements of epidemics, as
influenced over time by factors of the environment and
by human interference, are expressed in patterns and
rates.
Disease-progress curve
Disease-gradient or dispersal curve
49. Disease–progress Curve
The progress of an epidemic measured in terms of the
numbers of lesions/ the amount of diseased tissue, or
the numbers of diseased plants plotted over time is
called the disease–progress curve
Shows the progress of an epidemic over time, e.g.,
numbers of lesions, numbers of diseased plants, etc.
Also allows disease forecasting & selection of the best
control strategy for the particular disease & time
50. Disease–progress Curve
Basic epidemic patterns
Saturation type of curve
Three monocyclic diseases of different epidemic rates.
Sigmoid curve
Polycyclic disease, such as late blight of potato.
Bimodal curve
polycyclic disease, such as apple scab, in which the
blossoms and the fruit are infected at different, separate
times.
51. Schematic diagrams of disease–progress curves of some basic
epidemic patterns
Three monocyclic diseases of different epidemic rates
52. Schematic diagrams of disease–progress curves of some basic
epidemic patterns
Polycyclic disease, such as late blight of potato
53. Schematic diagrams of disease–progress curves of some basic
epidemic patterns
Bimodal polycyclic disease, such as brown rot of stone fruits, in which
the blossoms and the fruit are infected at different, separate times
54. Disease-gradient or dispersal curve
The progress of an epidemic measured in terms of changes
in the number of lesions/ the amount of diseased tissue,
and the number of diseased plants as it spreads over
distance, is called disease gradient curve (spatial pattern)
Disease–gradient curve: The percentage of disease and the
scale for distance vary with the type of pathogen or its
method of dispersal
Being small for soil borne pathogens or vectors and
Larger for airborne pathogens
The amount of disease is greater near the source of
inoculum
The amount of disease decreases with increasing distance
from the source
55. Schematic diagram of a disease–gradient curve. The percentage of
disease and the scale for distance vary with the type of pathogen or its
method of dispersal, being small for soil borne pathogens or vectors and
larger for airborne pathogens
59. Development of Epidemics
For epidemic, specific combination of environmental
factors must occur constantly or repeatedly, and at
frequent interval over a large area.
Epidemics occurs only when the combination of right
sets of condition occurs i.e. include
Temperature
Moisture
Wind
Insect vectors with susceptible stage of plant
60. Epidemics requires
repeated infection cycles
Presence of virulent pathogen
considerable time before a pathogen produces enough
individuals
set of favorable environmental conditions repeatedly
Large area under genetically uniform crop
61. Development of Epidemics
The most favorable combinations of conditions for
disease development do not occur very often over very
large areas
Spectacular plant disease epidemics that destroy crops
over large areas are relatively rare
However, small epidemics involving the plants in a
field or a valley occur quite frequently
With many diseases, e.g., potato late blight, apple scab,
and cereal rusts, the environmental conditions seem
usually to be favorable, and disease epidemics would
occur every year were it not for the control measures
62. Modeling of Plant Disease Epidemics
An epidemic is a dynamic process. It begins on a few
plants and then increase in severity and spreads over a
larger area.
It stops when all host plants are killed , become
resistant or harvested.
For our better understanding and prediction of
development of an epidemic, plant pathologists from
late 1960s have been developing models of common
and serious diseases.
63. Modeling of Plant Disease Epidemics
Model?
Models are generally crude simplifications of real
epidemics, roughly analogous.
Construction of a model takes into account all the
components and sub-components of plant disease.
Mathematical models;
It provides a great information about amount and efficacy of
inoculum , effects of environment, disease resistance of host,
effects of management strategies.
64. Modeling of Plant Disease Epidemics
For a model, a database of information is developed.
Database contains information on:
Crop
The disease incidence
The pathogen
Location
Crop canopy
Rain fall
Temperature
Wind velocity
Vector etc
65. Forecasting plant disease epidemics
Being able to forecast plant disease epidemics is stimulating and
also an indication of the success of modeling of particular
disease.
To develop a plant disease forecast, one must take into account
several characteristics of particular pathogen, host and
environment.
In monocyclic diseases, disease development may be predicted
by assessing the amount of initial inoculum.
In polycyclic diseases, disease development can be predicted by
assessing the rate of occurrence of infection cycles.
66. Forecasting plant disease epidemics
Some points related to forecasting of plant disease
epidemics
Disease diagnosis: The key to forecasting of any plant disease.
Evaluation of epidemic Thresholds.
Evaluation of Economic Damage Threshold.
Assessment of Initial Inoculum and of Disease.
Monitoring Weather Factors That Affect Disease Development