Biology and pathogenicity of Pestalotiopsis microspora and Colletotrichum siamense associated with circular leaf spot of rubber (Hevea brasiliensis)
,
and
Article Sidebar
Full Text: 
PDF
Main Article Content
Abstract
Circular leaf spot disease (CLSD) has recently emerged as an important foliar disease of rubber (Hevea brasiliensis) in Viet Nam, yet information on its associated pathogens remains limited. This study investigated the biological characteristics and pathogenicity of Pestalotiopsis microspora and Colletotrichum siamense associated with CLSD. Sixteen isolates of each species were obtained from diseased leaves collected in major rubber-growing regions of Viet Nam. Morphological characteristics were evaluated on different culture media and temperature regimes, while pathogenicity was assessed under laboratory and greenhouse conditions and confirmed through Koch’s postulates. Pestalotiopsis microspora showed optimal growth on malt extract agar at 25°C, whereas C. siamense grew most rapidly on potato-based media at 25–30°C. ITS sequence analysis showed ≥99% similarity between all isolates and reference sequences of P. microspora and C. siamense in GenBank. Disease severity index values on detached leaves ranged from 34.4–52.1% for P. microspora, 54.5–99.8% for C. siamense, and 92.0–100% for mixed inoculations (ANOVA, p < 0.01). Greenhouse inoculations showed a similar pattern. Among six rubber clones, RRIV 124 was the most susceptible under laboratory conditions. These results indicate that CLSD in Viet Nam is associated with a pathogen complex in which C. siamense is more pathogenic than P. microspora, while...
Article Details
Conflict of Interest
© 2026 The authors. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License.
References
Alchemi, P. J. K. (2022, December 14–15). Pestalotiopsis leaf disease: Identification, epidemiology studies, and selection of new clone [Conference presentation]. IRRDB Workshop on Pestalotiopsis Leaf Disease, Kuala Lumpur, Malaysia.
Arom, R. (2020, December 4). The new leaf fall disease in Thailand [Conference presentation]. IRRDB Online Workshop.
Bindu, R. (2022, December 14–15). Current status of leaf disease in India [Conference presentation]. IRRDB Workshop on Pestalotiopsis Leaf Disease, Kuala Lumpur, Malaysia.
Fernando, S. (2022, December 11–17). Current status of the circular leaf spot disease in Sri Lanka and the research programme [Conference presentation]. IRRDB Workshop on Pestalotiopsis Leaf Disease, Kuala Lumpur, Malaysia.
Hieu, N. D., Uyen, N. T. K., & Trang, N. T. T. (2026). Diversity, pathogenicity, fungicide sensitivity, and field management of the circular leaf spot pathogen complex on rubber trees in Vietnam. Journal of Rubber Research, 28, 719–736. https://doi.org/10.1007/s42464-025-00332-3
Hieu, N. D., Uyen, N. T. K., Trang, N. T. T., Mai, N. N., Vinh, N. P., Luan, D. N., & Nghia, N. A. (2023). Morphological characteristics of Pestalotiopsis spp. and Colletotrichum spp. associated with circular leaf spot disease newly detected on rubber trees in Dong Nai and Binh Phuoc provinces. In Proceedings of the National Conference on Plant Diseases in Vietnam 2023 (pp. 196 - 201). Agricultural Publishing House, Hanoi, Vietnam (in Vietnamese).
Kuruvilla, J. C. (2023, February 20–22). Pestalotiopsis and other epidemic diseases of rubber and their management strategies [Conference presentation]. IRRDB International Rubber Conference, Kuala Lumpur, Malaysia.
Kusdiana, A. P. J. (2020). Diagnosis penyakit gugur daun karet (Hevea brasiliensis Muell. Arg.). Jurnal Penelitian Karet, 38(2), 165–178. https://doi.org/10.22302/ppk.jpk.v38i2.730
Tajuddin, I., & Ibadallah, B. (2019, November 5). A rubber plantation’s experience to manage a new serious leaf disease [Conference presentation]. The First Meeting of ANRPC Technical Committee of Plant Protection, Kuala Lumpur, Malaysia.
White, T. J., Bruns, T., Lee, S., & Taylor, J. (1990). Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In PCR protocols: A guide to methods and applications (pp. 315–322). Academic Press.