phytophthora - die back

Question 1

DB type of organism

Answer 1

protist phytopthora cinnamomi

Question 2

DB mode of transmission

Answer 2

• indirect / vehicle
• direct = root to root contact
• infected soils, tools, fomites
• spread on the bottom of shoes and tires

Question 3

DB impact on host and symptoms

Answer 3

• stops roots absorbing water
• causes root rot which will result in plant death
• wilting as water no longer transported through xylem
• yellowing as can no longer photosynthesis
• water stress in all cells due to drop in osmotic gradient

Question 4

DB distribution

Answer 4

• south west of WA
• worldwide
• east coast and coast of tasmania

Question 5

DB treatment

Answer 5

• plant disease free material : good root stock and structure
• monitor tree health : changes in tree performance and symptoms
• good drainage : prevent water build up
• tree with phosphoric acid products (phosphite injections)
• control access : remove soil from shoes and tires

Question 6

DB life cycle

Answer 6

1. transmission mode indirect
2. zoospores are found in the soil
3. flagellated zoospores enter the plant near the growing tip of the roots
4. invades the roots of plants from the surrounding soil to obtain nutrients and moisture for growth and reproduction
5. lives in roots and destroys cells
6. prevents water from entering
   causes symptoms

Question 7

DB diagnostic test

Answer 7

• interpretation
• dieback interpreters following a logical process of evaluation historic and recent site info aerial imagery collecting and analyzing data
• lab testing
• antibody test