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Dieback Resistant Jarrah
Many jarrah trees die when they are infected by the root rot pathogen Phytophthora cinnamomi (the cause of Phytophthora dieback disease). However some jarrah trees survive in forest sites where dieback has had a high impact for many years. Are these trees resistant to dieback?  The short answer to this question is ‘maybe’.
A long-term research and development project between Alcoa, the Department of Environment and Conservation (DEC), Murdoch University and Edith Cowan University studied the surviving trees.  The team found that some of the seedlings grown using the seed from these surviving jarrah trees had a relatively high resistance to P. cinnamomi. A project was established to identify and propagate these disease resistant plants. 
Seedlings which showed high dieback resistance in these trials were cloned using tissue culture techniques.  Alcoa’s Marrinup Nursery supported the project by producing large numbers of the tissue cultured dieback resistant jarrahs in the micropropagation laboratory.  However, the cost of using tissue culture propagation methods was prohibitive for mass production of these plants.
As resistance to dieback is an inherited trait then a cheaper way to propagate the jarrah trees is to grow them from seed produced by the dieback resistant plants. To do this three seed orchards were established to produce the required amount of seed.
Since 1998, orchards of dieback resistant clones, produced by tissue culture, have been established at Huntly, Manjimup and Pinjarra.  In 2003, more trees were planted in the orchards; to replace deaths and to increase genetic diversity.
The seeds from the orchards will be used to rehabilitate areas of dieback affected forest and for field trials with community conservation groups.  The seedlings produced will also be used for further research into understanding how these special plants are able to resist the pathogen.

DRJ clones

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Dieback resistant jarrah clones produced by Marrinup Nursery's tissue culture laboratory.

Dieback resistant jarrah seed orchards

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Dieback resistant jarrah seed orchards provide the seed to mass produce these important trees.

Flower Small

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Further research into dieback resistant jarrah may teach us more about reducing dieback's impact in the jarrah forest.