Detection of pear decline disease in pear and quince in the eastern Mediterranean region of Turkey

Investigations were carried out to detect PD disease and its natural transmission in five pear and two quince orchards in Adana, Hatay and Mersin provinces in the eastern Mediterranean region of Turkey in 2003 and 2004. Symptomatic trees were visually inspected in pear orchards planted by cvs. Williams (Hunkar), Starkrimson and three local cultivars Akca, Ankara and Mustafa Bey, in quince orchards established by cvs. Ekmek and Limon from mid-May to mid-October. While symptomatic trees were exhibited different abnormalities as small, few and light-green leaves during the observation periods, and the leaves turned to dark-red colour in the late summer. Leaf and shoot samples were collected from randomly selected trees at the end of the August. A total of 92 pear and 12 quince samples were tested for the presence of phytoplasmas by nested-PCR assays. RFLP analyses of PCR products obtained with primer pair f01/r01 enabled identification of pytoplasma related to the disease. Seven out of the total pear samples including local cultivars were found to be infected with Ca. Phytoplasma pyri in the region. No infected quince samples were found by molecular assays. C. pyri L. (Homoptera, Psillidae) was collected from investigated pear orchards from August to September in both years. PCR-RFLP analyses were carried out on batches containing 10 psylla adults in 2004. Two out of the 7 insect samples were tested positive for the agent by PCR-RFLP analyses. Periwinkle (Catharanthus roseus) test plants exposed in the orchard in Adana in 2004 showed symptoms related to the disease by the rate of 3/75 and I out of these plants were found to be infected with Ca. Phytoplasma pyri. These results indicate that C. pyri could transmit the agent and natural transmission of PD disease has been in the region.