Re: UK: Sudden death for thousands of trees
An overview is available at South Australia government website. Here an extract:
Source: South Australia Govt, Environment:
http://www.environment.sa.gov.au/biodiversity/pdfs/phytophthora.pdf
What is Phytophthora?
Phytophthora (pronounced fy-TOFF-thora) species are
soil and waterborne fungi that cause disease and often death to a wide variety of native plant species, exotic fruits and vegetables.
The most common species is
Phytophthora cinnamomi, which is also referred to as ?Pc?.
Phytophthora attacks the roots and stems of plants.
Early symptoms of the disease are
root-rot, and depending on the plant species, stem rot and eventual death.
In effect, the susceptible plants die from an
inability to take up sufficient water and nutrients.
The first symptoms of infection are yellowing of the foliage followed by dieback of the entire plant.
Phytophthora cinnamomi is considered a threat to
over 1000 plant species worldwide.
While it is still uncertain exactly how many species in Australia are threatened, it is expected to be in the hundreds.
The best indicator species for the disease in South Australia is the yacca or grass-tree
Xanthorrhoea sp., as it is highly susceptible.
Other susceptible species are
Banksia sp., Myrtle Wattle Acacia myrtifolia, Cone-bush Isopogon ceratophyllus, Messmate Stringybark Eucalyptus obliqua, Mount Lofty Bush-pea Pultenaea involucrata and many others.
A group of dead or dying susceptible plant species is generally a good indication of Phytophthora infestation.
Fruits (apples, pears, cherries, apricots, peaches, grapes, olives, macadamias, chestnuts and walnuts),
vegetables (potatoes) and
ornamental plants (lilies, camelias, hibiscuses and rhododendrons) are also effected by Phytophthora species.
Where is Phytophthora found in SA?
The fungus is
native to South-East Asia and has probably reached Australia in a variety of ways.
In Western Australia it is thought to have arrived around 1900 in orange trees brought in from Indonesia, while in the Mount Lofty Ranges (SA) it probably arrived around 1970 in infested berries from nurseries in the Dandenong Ranges.
On Kangaroo Island, Phytophthora has been noticed since 1993 and the most likely cause of introduction is through infested soil on vehicles from the mainland.
Phytophthora is able to grow in areas where
average annual rainfall is greater than 400 mm (16 inches), and
soils are acid to neutral.
It has the ability to live in most of the southern areas of South Australia.
Phytophthora has been found in the Mount Lofty Ranges around Adelaide, the Fleurieu Peninsula, on Kangaroo Island and in the Lower South East.
The presence of Phytophthora is suspected on Eyre Peninsula.
What does Phytophthora look like?
Phytophthora is
a soil and waterborne microscopic fungus.
It grows in a threadlike fashion through the roots and trunks of infested plants. The only visible sign of its presence is sickness or death of the plants it attacks.
The fungus
reproduces by spores (like minute seeds) or by
mycelia (mature strands of fungus).
There are two common spore types.
Zoospores are only present when there is considerable moisture in the soil.
Another type of spore called a
chlamydospore is long-lived.
These spores can remain dormant for many years until conditions are right for fungal growth (ie. warm and moist conditions).
How does Phytophthora spread?
Phytophthora can spread
from plant to plant through root contact.
It is spread most rapidly when rainfall coincides with warm temperatures, generally in spring, summer and early autumn.
The disease can spread very quickly with the help of ?artificial? factors such
as human disturbance.
The transport of infested soil and plant material by vehicles and heavy machinery (such as in firefighting, logging and roadworks) is probably the single most important factor in the spread of this fungus.
A bulldozer not cleaned after working in an infested area can easily spread the disease to an uninfested site many kilometres away.
Bushwalkers and bike riders can also spread the disease by transferring mud on their boots and tyres.
For more information see the information sheet ?Phytophthora Bushwalking Guidelines? available from Department for Environment and Heritage offices.
How you can help stop the spr ead of Phytophthora.
The best way to control the fungus is to prevent the transfer of infested soil or plant material.
? Avoid driving, riding or walking in areas when soils are wet and sticky.
? Stay on designated roads and tracks. Vehicles, bikes and people moving off roads into infested areas may pick up infested soil and transfer it to uninfested areas.
? Brush soil off vehicles, bikes, boots and camping gear before and after each trip. Do not take them home to clean.
? Obey road signs. Roads and tracks may be closed, sometimes permanently, to help stop the spread of Phytophthora.
? Use wash down or hygiene stations when provided.
? Protect your bush. Ensure that purchased plants are free of hytophthora.
? Report any unusual plant death. Please report the death of groups of susceptible plants to your local Department for Environment and Heritage office.
For further information please contact:
Department for Environment and Heritage Telephone: (08) 8552 0306, or see SA White Pages for your local Department for Environment and Heritage office.
Online information available at:
http://www.environment.sa.gov.au/biodiversity/plandsand.html
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