Lecture 1

Question 1

Define Plant Pathology:

Answer 1

Plant Pathology is the study of:

• living entities and environmental conditions that cause disease in plants
• mechanisms by which these factors result in disease
• interactions between disease agents and hosts
• disease prevention and management

Question 2

What occured in 1845-1846?

Answer 2

Irish Potato Famine

Question 3

Who is the father of plant pathology?

What did he do?

Answer 3

Anton deBary

• In controlled experiments, proved that a fungus causes late blight (1861)

Question 4

What did the Irish Potato Famine introduce?

Answer 4

• The political aspects of the food supply
• Risks of genetic uniformity in crops
• Problems when new crops are distributed throughout the world

Question 5

Define Plant Disease:

Answer 5

• a condition of abnormal physiology in a
  susceptible host plant that is a result of
  the plants constant association with a
  disease causing agent within a set of
  favorable environmental conditions.

Question 6

Name all aspects of the disease triangle.

Answer 6

Question 7

Name the 2 types of disease causal agents:

Answer 7

1. Biotic (infectious)
2. Abiotic (non-infectious)

Question 8

Explain Biotic as a causal disease agent:

Answer 8

. **Biotic (infectious) **

• organism (pathogen) grows, multiplies, and spreads to other plants
• 10% of diseases reported

Question 9

Explain Abiotic as a causal disease agent:

Answer 9

• environmental conditions that impact
  plant development (physiogens)
• much more common: 90% of diseases
  reported (injury not disease)

Question 10

Explain Abiotic Causal Agents (physiogens):

Answer 10

• **Physical factors **
- temperature
- moisture
• Chemical factors
- air pollutants
- pesticides
- fertilizers and salts
• Mechanical factors
- everything else

Question 11

Explain Biotic Causal Agents (pathogens):

Answer 11

• Fungi (largest group of plant pathogens)
• Prokaryotes (no nuclear membrane)
– bacteria
– mollicutes (phytoplasmas, spiroplasmas)
• Nematodes (round worms)
• Viruses (nucleic acid with a protein coat)
• Viroids (naked RNA with no protein coat)
• Parasitic plants
• Algae
• Protozoa
• Insects and mites

Question 12

What is Mycology?

Answer 12

The study of Fungi

Question 13

What is the most common (important) of the plant pathogens? explain.

Answer 13

Fungi

• Most important as agents of decay
• Can attack wood products, leather goods, fabrics,
petroleum products, foodstuffs

• Infects animals and plants

Question 14

Explain Bacteria:

Answer 14

• 1600 species are known, most are saprophytic *(obtains its nutrtion from assimilating organic matter) *
• Important as decomposers and in nitrogen recycling
• Cause human, animal (e.g., tuberculosis, pneumonia,
typhoid fever), and plant diseases
• Actinomycetes produce antibiotic compounds
• Shapes: rod, spherical (cocci), spiral, or filamentous
• Reproduce by fission (they divide in two)

Question 15

Explain Virus:

Answer 15

• entity that contains genetic material within a protein coat that can only reproduce using the metabolic processes of a suitable host cell

Question 16

Define the Disease Cycle:

Answer 16

• Series of events from
  the initial contact between the
  pathogen and plant….. to the ultimate
  demise of the plant….. and the
  reproduction and spreading of
  the pathogen.

Question 17

What are the principles of disease control?

Answer 17

• Exclusion
– Prevent movement of pathogen into
uninfected areas
• Eradication
– Eliminate or reduce pathogen levels on
site
• Resistance
– Improve plants ability to tolerate or
recover from attack
• Protection
– Prevent attack with chemical