Surveys on phytoplasma diseases of fruit trees in Turkey
Stone fruits are important crops in Turkey, but since 1999 severe decline of plums (Prunus domestica and P. salicina), apricots (Prunus armeniaca) and pears (Pyrus communis) has been observed in nurseries and commercial orchards. Observed symptoms suggested phytoplasma infections. Earlier studies had detected ‘Candidatus Phytoplasma prunorum’ (associated with European stone fruit yellows) in 1 Japanese plum at Izmir (Aegean region), in apricot trees in the provinces of Içel and Adana (Mediterranean region) and in 1 almond (P. amygdalus), 1 myrobalan (P. cerasifera) and 2 peach (P. persicae) trees in the east part of the Mediterranean region. ‘Candidatus Phytoplasma pyri’ (associated with pear decline – EPPO A2 list) was also detected in 1 pear tree in the east Mediterranean region. In order to better understand the situation of phytoplasma diseases, surveys were carried out in 10 provinces of Turkey in commercial orchards of Bursa (Marmara region), Içel, Hatay, Kahramanmaraş (Mediterranean region) and Malatya (East Anatolia region), as well as in germplasm orchards of Adana, Antalya, Gaziantep, Isparta, Içel (all in Mediterranean region) and Yalova (Marmara region). In total, 270 stone fruit trees (almond, apricot, nectarine, peach, plum) and 6 pear trees showing phytoplasma symptoms were collected and tested (PCR, RFLP). The overall phytoplasma infection in tested samples was 10.2%. 54.8% of samples from germplasm orchards (mainly planted with cultivars of foreign origin) were infected by ‘Ca. P. prunorum’ whereas the disease incidence was only 3.2% in commercial orchards. ‘Ca. P. prunorum’ was detected in all provinces studied (except Malatya and Kahramanmaraş). The high incidence in germplasm orchards could indicate that imported material is largely responsible for its introduction into Turkey. ‘Ca. P. pyri’ was detected in commercial orchards of Bursa, as well as in its vector Cacopsylla pyri (specimens were collected from symptomatic pear trees). It is underlined that there is no established certification programme for fruit trees in Turkey. The EPPO Secretariat had previously no data on the occurrence of both phytoplasmas in Turkey.
The situation of ‘Candidatus Phytoplasma prunorum’ in Turkey can be described as follows: Present, found on several Prunus species in the Aegean and Mediterranean regions.
The situation of ‘Candidatus Phytoplasma pyri’ in Turkey can be described as follows: Present, detected in the province of Bursa (Marmara region).
Sources
Ulubaş Serçe Ç, Gazel M, Çaglayan K, Baş, Son L (2006) Phytoplasma disease of fruit trees in germplasm and commercial orchards in Turkey.
Journal of Plant Pathology 88(2), 179-185.