First report of a phytoplasma causing pear decline in Australia
Pear trees showing decline symptoms were observed in one of the main pear-growing region, the Goulburn Valley in Victoria, Australia. Affected trees show restricted foliation, interveinal chlorosis, and reduced productivity. PCR was used to detect phytoplasmas in symptomatic trees, and restriction fragment length polymorphism (RFLP) analysis showed that patterns obtained were identical to those from sweet potato little leaf phytoplasma. The authors noted that a recent survey has shown that phytoplasmas of that group (which also include papaya yellow crinkle and papaya mosaic) are prevalent in Australia and occur in a wide range of host plants. They felt that this finding is not in contradiction with observations made in California (US) where pear decline appears to be associated with genetically different phytoplasmas (Kirkpatrick et al., 1993). This is the first report of a phytoplasma causing pear decline in Australia.
Sources
Schneider, B.; Gibbs, K.S. (1997) Detection of phytoplasmas in declining pears in Southern Australia.
Plant Disease, 81(3), 254-258.
Kirkpatrick, B.C.; Purcell, A.H.; Gao, J.L.; Fisher, J.F.; Uyemoto, J.K. (1993) At least three genetically distinct MLOs cause pear decline and peach yellow leafroll disease in California.
Phytopathology, 83, p 1341.