A disease occurs when a disease- causing agent, or pathogen, meets the right host organism under environmental conditions favorable to disease development. These three elements, pathogen, host, and environmental conditions, make up the disease triangle.
What are the factors that causes plant diseases?
Important environmental factors that may affect development of plant diseases and determine whether they become epiphytotic include temperature, relative humidity, soil moisture, soil pH, soil type, and soil fertility.
What are the three 3 factors that affect the likelihood of infection occurring from a pathogen?
Common pathogen factors are immune evasion, high viral load and low infectious dose.
What are the three types of plant diseases?
- Black Spot.
- Other Leaf Spots.
- Powdery Mildew.
- Downy Mildew.
- Blight.
- Canker.
What are three factors that influence the spread of emerging diseases?
Several factors contribute to the emergence and re-emergence of infectious diseases, but most can be linked with the increasing number of people living and moving on earth: rapid and intense international travel; overcrowding in cities with poor sanitation; changes in handling and processing of large quantities of food …
What are two things that cause most plant diseases?
Fungi and Fungal-Like Organisms: Collectively, fungi and fungal-like organisms (FLOs) cause more plant diseases than any other group of plant pathogens. Fungi and FLOs are heterotrophic (cannot make their own food), eukaryotic organisms that have a filamentous growth habit and which may or may not produce spores.
How development of disease occurs in plants?
In order for a disease to develop, a pathogen must be present and successfully invade plant host tissues and cells. The chain of events involved in disease development includes inoculation, penetration, infection, incubation, reproduction, and survival (Figure 70).
What are the stages of disease cycle?
- survival.
- spore germination and infection.
- early root disease development.
- late root disease development.
- spread.
- foliar disease development.
- production of survival structures.
What are plant diseases?
Plant disease is defined as the state of local or systemic abnormal physiological functioning of a plant, resulting from the continuous, prolonged ‘irritation’ caused by phytopathogenic organisms (infectious or biotic disease agents).
What are diseases caused by fungi in plants?- Leaf Spots. Leaf spots (other names: anthracnose, scab, leaf blotch, shot hole) are usually rather definite spots of varying sizes, shapes and colors. …
- Leaf Blights. …
- Rusts. …
- Powdery Mildew. …
- Downy Mildew.
What is the most common plant disease?
- Powdery Mildew. Most powdery mildew are very host specific, mildew on cucumbers will not infect roses. …
- Black Spot. This is a common fungal disease of roses. …
- Bacterial Canker or Blight. …
- Shot Hole. …
- Black Knot. …
- Rust. …
- Late Blight / Early Blight. …
- Apple Scab.
What are three 3 external physical barriers that help the body to defend against infection?
The skin, mucous membranes, and endothelia throughout the body serve as physical barriers that prevent microbes from reaching potential sites of infection. Tight cell junctions in these tissues prevent microbes from passing through.
What factors influence the development of infection?
- Whether the microorganism produces toxins, enzymes, or other substances. …
- Whether it develops resistance to antimicrobial drugs.
What are the 4 factors that make a person more susceptible to infection?
We all have different susceptibility Multiple innate factors (e.g., age, nutritional status, genetics, immune competency, and pre-existing chronic diseases) and external variables (e.g., concurrent drug therapy) influence the overall susceptibility of a person exposed to a virus.
What are the emerging and re emerging diseases?
Emerging diseases include HIV infections, SARS, Lyme disease, Escherichia coli O157:H7 (E. coli), hantavirus, dengue fever, West Nile virus, and the Zika virus. Reemerging diseases are diseases that reappear after they have been on a significant decline.
What is plant disease explain the methods of plant disease control?
A variety of chemicals are available that have been designed to control plant diseases by inhibiting the growth of or by killing the disease-causing pathogens. Chemicals used to control bacteria (bactericides), fungi (fungicides), and nematodes (nematicides) may be applied to seeds, foliage, flowers, fruit, or soil.
What are the steps of pathogenesis?
To cause disease, a pathogen must successfully achieve four steps or stages of pathogenesis: exposure (contact), adhesion (colonization), invasion, and infection.
How many plant diseases are caused by fungi?
Collectively, fungi and fungal-like organisms (FLOs) cause more plant diseases than any other group of plant pest with over 8,000 species shown to cause disease.
What plant disease is not caused by fungus?
Thus, the correct answer is A i.e., Black rot of crucifers.
What causes fungal diseases?
Fungal infections are common throughout much of the natural world. In humans, fungal infections occur when an invading fungus takes over an area of the body and is too much for the immune system to handle. Fungi can live in the air, soil, water, and plants.
What are the three common diseases in the nursery?
- Damping off:
- Leaf Web Blight.
- Colletotrichum Leaf spot and blight:
- Alternaria Leaf spot and blight:
- Pseudocercospora Leaf spot: It is caused by Pseudocercospora subsessilis. …
- Powdery Mildew:
- Other Foliar Diseases:
What are the classification of plant diseases?
According to this criterion, plant diseases are classified into two types: infectious (biotic) diseases, which are caused by eukaryotes, prokaryotes, parasitic higher plants, viruses/viroids, nematodes, and protozoa, and noninfectious (abiotic) diseases, which are caused by different extreme environmental conditions [5 …
What are the 3 levels of the immune system?
- Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection. …
- Adaptive immunity: Adaptive (or active) immunity develops throughout our lives.
What are the 3 lines of defense against pathogens?
D. Reviewed by Emily Henderson, B.Sc. The human body has three primary lines of defense to fight against foreign invaders, including viruses, bacteria, and fungi. The immune system’s three lines of defense include physical and chemical barriers, non-specific innate responses, and specific adaptive responses.
What is the 1st 2nd and 3rd line of defense immune system?
The body’s first line of defense is the innate immune system. It consists of physical barriers (such as the skin and mucous membranes). … The body’s third line of defense is highly specific adaptive immune responses that target the invading pathogen.
What are key steps in the process of the development of infection and disease?
The infectious disease process includes the following components: (1) agent (2) reservoir (3) portals of entry and exit (4) mode of transmission (5) immunity.
