DIEBACK AND CANKER IN AUSTRALIAN PISTACHIOS

A project was undertaken to quantify, isolate and identify the cause of canker and dieback of pistachio trees in Australia.
This serious disease was first observed in pistachio trees 3–4 years ago and, since then, has increased to the point where some orchards have over 70% of trees exhibiting disease symptoms.
In two orchards, systematic sampling of trees exhibiting symptoms of the disease syndrome has lead to the isolation of a Xanthomonas bacterium.
Several weakly pathogenic fungi have also been isolated, as well as a strain of Verticillium tricorpus. Mapping shows aggregation of the disease symptoms along and, to a lessor extent, across rows, suggesting mechanical and insect vectored transmission from disease loci.
The incidence of various disease symptoms were as follows: ooze 0–89%, dieback 0–20%, canker in the scion 0–77%, canker in the rootstock 0–1.5%, and shoot death 0–27%. The different patterns of aggregation for different symptoms suggests more than one cause of the disease syndrome.

II International Symposium on Pistachios and Almonds

M. Edwards, C. Taylor

pistachio, disease

https://doi.org/10.17660/ActaHortic.1998.470.84