Phytophora dieback (jarrah dieback)

Question 1

Cause

Answer 1

Protist - Phytophthora cinnamomi

Question 2

Distribution

Answer 2

Australia, Specifically WA

Question 3

Transmission

Answer 3

• Phytophthora spreads naturally by moving through soil and the roots it infects, and in run-off.
• Animals spread Phytophthora when infested soil gets caught in their feet and fur and it drops off in uninfected areas.
• Humans spread Phytophthora when they disturb and move infested soil. Through their activities, humans have spread Phytophthora further and faster than any other means of spread.

Question 4

Life Cycle

Answer 4

Sexual reproduction can produce oospores, but these are typically not infectious. They develop into a mycelium which can produce zoospores by asexual reproduction. The zoospores infect the root of the host and develop into a cyst before forming mycelia once inside the root.

Question 5

Impact on Host

Answer 5

Infects roots of plants. Takes nutrients from root cells, killing roots and affecting water uptake. Normally results in death.

Question 6

Treatment

Answer 6

There is no way to cure/treat dieback

Question 7

Prevention/control

Answer 7

• Spray with phosphite increase resistance to infection.
• Eradicate the areas by killing all trees and sterilising soil.
• Dieback training - otherwise known as green card training is necessary if in dieback areas.
• Cleaning shoes by wiping them and spraying them with methylated spirits to kill dieback. And washing down equipment.
• Controlling dieback risk areas by quarantine:
  a. temporary road closures during wet weather when there is a greater likelihood that carriers will pick and transport potentially infested soil
  b. restricted access for management purposes only and/or
  a requirement for a permit to enter