Dieback

What is it?

Phytophthora dieback is an introduced plant disease, which feeds on roots of the host plant, killing up to 40 per cent of all Western Australian native plants by starving them of water and nutrients. The movement of infected soil, plant material or water containing dieback spores spreads this disease. There are approximately 60 known species of phytophthora dieback in Australia, which can ultimately be more devastating than salinity to our forests and hinterland.

Where is it found?

Phytophthora dieback has been found in many of south-west Western Australia's national parks, nature reserves, along the coastline and in metropolitan Perth bushland areas.

What does it look like?

You can identify phytophthora dieback in your home garden or bush environment quite easily as the symptoms include wilting, yellowing and browning of leaves, defoliation, dark and sunken areas on stems and branches, loose bark, browning of wood within dying branches and branch dieback. The plants die very quickly and display typical symptoms of water and nutrient starvation in a very short time. There are indicator species which include most of the Proteaceae family, so the banksias, grevilleas, macadamias, avocados are all highly susceptible to this disease.

If you have a plant that's beginning to die quickly, remove the bark at the base of the tree and if you notice a dark, dead area joining a healthy area, this is a sign that the disease is active in the dead area and is blocking water and nutrients from entering the plant.

What should I do if I find it on my rural property?

To control this disease, try administering an environmentally benign chemical such as phosphite. It is usually applied as potassium phosphite which is derived from phosphorous acid neutralized with potassium hydroxide and is injected into the trunks of larger trees or can be sprayed from backpacks onto smaller plant species.

To help reduce the introduction of dieback into your garden, purchase your plants from accredited nurseries that follow strict hygiene procedures. Phytophthora dieback can easily be spread in nurseries by contaminated potting mix and if pots are placed on the ground, the virus can literally spread between pots. Pots should be kept off the ground and have good drainage.

Try to reduce the number of established plants being transplanted from one garden to another as they can also spread the disease. Propagating from seed and cuttings is safer because there is no soil transported with stock.

Dieback

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What does it look like?

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If you have a plant that's beginning to die quickly, remove the bark at the base of the tree and if you notice a dark, dead area joining a healthy area, this is a sign that the disease is active in the dead area and is blocking water and nutrients from entering the plant.

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What should I do if I find it on my rural property?

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Try to reduce the number of established plants being transplanted from one garden to another as they can also spread the disease. Propagating from seed and cuttings is safer because there is no soil transported with stock.