MODULE 5

Question 1

Infectious plant diseases are caused by living (biotic) agents, or ___

Answer 1

pathogens.

Question 2

Major Organisms Causing Plant Disease?

Answer 2

Fungi, Bacteria, Nematodes, Virus

Question 3

• Tiny, simple plants called molds, generally measured in microns
  -No chlorophyll; depends on other organisms or plant tissues for food
  • Multiply by spores which produce threadlike filaments that enter the
  host directly or through natural openings
  • Get support from the host by extracting its nutrients
  • Can survive in adverse conditions through special structures (sclerotia)
  and infects again when favorable condition prevails

Answer 3

Fungi

Question 4

• Small, one-celled organism, measured in microns
• Lack chlorophyll, cannot produce its own
• Reproduced by cell division every 15-20 minutes
• Need wounds or entry points to enter the host
• Survive in seeds, plant debris, soil, tools
• Spread by wind, water, insects, tools, or soil
• Generally cause rotting of host tissues

Answer 4

Bacteria

Question 5

• Smaller than fungi and bacteria, measured in nanometer
• Can be seen only under the electron microscope
• Strictly dependent on living organisms for food and reproduction

Answer 5

Virus

Question 6

Thread-like unsegmented worms which are usually elongated and cylindrical in shape

Answer 6

Nematodes

Question 7

A ___ is a plant that can become infected by a pathogen.

Answer 7

host

Question 8

Abiotic Agents main factors

Answer 8

Watering, Temperature, Air movement, Humidity