New reports of Diplodia bulgarica, an emerging pest of apple
Diplodia bulgarica is a fungal pathogen that was first described in 2012, affecting crap apple (Malus sylvestris) in Bulgaria and causing cankers and dieback on apple (M. domestica). Since 2017, further reports of D. bulgarica have been made from Asia, Europe and the United States of America:
- Serbia: During apple harvests from 2016 to 2018, D. bulgarica was identified as a one of seven fungal pathogens that caused pre- and post-harvest apple fruit decay in orchards and stores across Serbia (Vučković et al., 2022).
- India: During the 2017-2018 growing season, black canker symptoms were observed on apple trees from commercial orchards in several apple-growing regions (Nabi et al., 2020).
- Germany: in 2018, D. bulgarica was identified to cause black cankers, and in extreme cases death, of apple and pear (Pyrus communis) trees in an organic orchard in Baden-Württemberg (Hinrichs‐Berger et al., 2021). A survey in 2023 showed that the pathogen was present in nearly all German states (Zugschwerdt et al., 2023).
- Türkiye: in 2019, D. bulgarica was identified as the cause of canker symptoms on apple trees in Isparta province (Eken, 2021).
- USA (California): in winter 2023, D. bulgarica was identified as the cause of black canker symptoms on apple trees in two commercial orchards in Sonoma County, California. Symptomatic trees ranged from 10-30% of trees in each area (Elfar et al., 2024).
- China (Xinjiang): in May 2024, black rot cankers were observed on M. domestica and M. sieversii trees in Ili Kazakh Autonomous Prefecture. About 30-40% of trees in each area were symptomatic (Xie et al., 2025).
- Poland: in summer 2024, D. bulgarica was identified as the causal agent of black cankers on branches and trunks of 24- and 60-year-old apple trees in a historical garden in Nieborów, Łowicz County, Łódź Voivodeship. Over 40% of Malus trees in the area were symptomatic (Głos and Michalecka, 2026).
Sources
Eken C (2021) Diplodia bulgarica, a new record for Turkey. Mycotaxon 136, 669–673.
Elfar K, Carachure C, Bustamante MI, Andrews E, Eskalen A (2024) First report of Diplodia bulgarica causing black canker on apple in California. Plant Disease 108(2), 531 https://doi.org/10.1094/PDIS-10-23-2031-PDN
Głos H, Michalecka M (2026) First detection of Diplodia bulgarica, a new pathogen causing black canker of apple trees in Poland. Scientific Reports 16, 7433 https://doi.org/10.1038/s41598-026-38714-1
Hinrichs‐Berger J, Zegermacher K, Zgraja G (2021) First report of Diplodia bulgarica causing black canker on apple (Malus domestica) and pear (Pyrus communis) in Germany. New Disease Reports 43(1), e12004 https://doi.org/10.1002/ndr2.12004
Nabi SU, Raja WH, Mir JI, Sharma OC, Singh DB, Sheikh MA, Yousuf N, Kamil D (2020) First report of Diplodia bulgarica a new species causing canker disease of apple (Malus domestica Borkh) in India. Journal of Plant Pathology 102(2), 555-556 https://doi.org/10.1007/s42161-019-00445-w
Vučković N, Vico I, Duduk B, Duduk N (2022) Diversity of Botryosphaeriaceae and Diaporthe species associated with postharvest apple fruit decay in Serbia. Phytopathology 112(4), 929-943 https://doi.org/10.1094/PHYTO-07-21-0304-R
Xie S, Wu H, Wang Y, Chen C, Gong F, Guo Y, Li H, Zhang M (2025) First report of Diplodia bulgarica causing black rot canker on apple in China. Plant Disease 109(9), 1987 https://doi.org/10.1094/PDIS-04-25-0830-PDN
Zugschwerdt J, Zegermacher K, Zgraja G, Schrader G, Clovis Douanla-Meli C, Hinrichs‐Berger J (2023) Diversity and distribution of Diplodia spp. – causative agent of black canker on pome fruit trees in Germany. Journal für Kulturpflanzen, 75 (07-08), 196–201. https://doi.org/10.5073/JfK.2023.07-08.03