General Information: Phytoplasmas inhabit phloem (food-conducting vascular tissue) sieve elements of plants where they cause a variety of diseases. Transmission between plants is via insects that feed on the phloem. Candidatus Phytoplasma australiense was identified in diseased Chardonnay grapevines from South Australia. Symptoms include a yellowing of the leaves and reduced leaf size, which leads to reduced plant size and lower yields.