Although boysenberry is strictly not a new host of “Ca. P.australiense”, here we report a new phytoplasma association
in plants exhibiting symptoms that differ from Boysenberry decline. During a study to determine the cause of Boysenberry
decline in the late 1990s, 4 out of 20 symptomatic boysenberry plants tested positive for “Ca. P. australiense”
(Wood et al. 1999). It was concluded that the fungus C. rube causes Boysenberry decline, however the possibility that “Ca.P. australiense” may be involved in the disease was not totally ruled out. These recent results suggest that “Ca. P. australiense” is associated with a disease different than Boysenberry decline.
Perhaps the symptoms associated with the phytoplasma were previously being masked by the more dominant
Boysenberry decline symptoms (M. Andersen, personal communication). Further work is required to demonstrate
association between the new symptoms and the phytoplasma.
Other phytoplasmas that have been recorded in Rubus spp. include Rubus stunt (16SrV) in the UK, North America and
Europe (Lee et al. 2000), Aster yellows (16SrI) in the UK (Reeder et al. 2010) and Pakistan (Fahmeed et al. 2009), a
group 16SrIII phytoplasma in the UK (Davies 2000), and Black raspberry witches’-broom phytoplasma (16SrIII-Q) in
North America (Davis et al. 2001).
The relationship between the group 16SrIII phytoplasmas detected in Rubus spp. in the
UK and North America is unknown as the 16S rRNA gene sequence is available for only one of them.