Status and epidemiology of Pear Decline (Candidatus Phytoplasma Pyri, PD) and Apple Proliferation (Candidatus Phytoplasma Mali, AP) in Belgium 

Phytoplasma diseases cause serious problems in hundreds of herbaceous and woody plant species in the world. In Europe, specifically the impact of Candidatus Phytoplasma mali (apple proliferation phytoplasma) and Candidatus Phytoplasma pyri (pear decline phytoplasma) is of major concern to our apple and pear growing industry. Both phytoplasma diseases disturb the tree growth leading to
malformation. In apple typically a witches ‘broom like growth of the shoots is induced and in pear early autumn discoloration of the leaves is a striking characteristic. Both phytoplasma diseases also cause enormous economic losses due to reduced fruit production and quality.
This study, in the framework of a 2 year research project (REPEDAP), aims to collect information on the status of both pathogens in Belgium. Additionally, answers to specific epidemiological characteristics of the disease such as phytoplasma titers and distribution in a tree throughout the season are also investigated. This information is of particular importance in view of a reliable
diagnostic method, including the sampling procedure. This presentation will focus on the mid‐term results of the project, also presenting the results of the survey conducted in apple and pear orchards in Belgium during 2013.