Presence and distribution of apple proliferation disease in the Kyustendil region of Bulgaria

Aneliya Z. BORISOVA; Aneliya Raykova

doi:10.55779/nsb17212467

Authors

Aneliya Z. BORISOVA Institute of Agriculture-Kyustendil, Department of Agrotechnology, Plant Protection and Economy on Crops, Kyustendil 2500, Agricultural Academy (BG) https://orcid.org/0000-0003-3062-2073
Aneliya Raykova Institute of Agriculture-Kyustendil, Department of Agrotechnology, Plant Protection and Economy on Crops, Kyustendil 2500, Agricultural Academy (BG) https://orcid.org/0000-0003-1672-3345

DOI:

https://doi.org/10.55779/nsb17212467

Keywords:

'Candidatus Phytoplasma mali', detection, DAS-ELISA, Malus domestica, PCR, symptoms

Abstract

Apple proliferation is a significant economic disease affecting cultivated apple trees across Europe. This study examines the presence, distribution, and symptomatic expression of apple proliferation disease among apple cultivars in commercial orchards in the Kyustendil region of Bulgaria. A total of 335 apple trees were sampled from the experimental and three commercial orchards of the Institute of Agriculture - Kyustendil and from fifteen private orchards. The collected samples were analyzed using DAS-ELISA to detect the presence of ‘Candidatus Phytoplasma mali’, the causal agent of the disease. Nine serologically identified infected trees were subsequently subjected to PCR analysis following DNA extraction from the phloem using a modified mini CTAB method. The study confirmed that symptoms such as witches’ brooms and enlarged stipules were consistently associated with the presence of ‘Ca. Phytoplasma mali’, as detected by serological and molecular methods. While useful for field identification, these symptoms are not conclusive diagnostic markers without laboratory confirmation. A relatively high incidence of phytoplasma infection (23.6%) was observed in apple orchards in the Kyustendil region, primarily based on serological analyses of symptomatic trees. Moreover, molecular confirmation ‘Ca. Phytoplasma mali’ was achieved through PCR analysis. Given that ‘Ca. Phytoplasma mali’ is transmitted by insect vectors, timely removal of infected trees is essential to mitigate disease spread and reduce economic losses.

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