<![CDATA[Abstract. Gitapawana, Amzeri A, Azis MRA. 2026. Associated pathogen groups and contrasting disease patterns in Criollo tobacco under field conditions and grow-out assessment. Biodiversitas 27 (9): d270922. https://doi.org/10.13057/biodiv/d270922. Criollo tobacco is an economically important cigar tobacco cultivar in Indonesia, yet information on associated pathogen groups and disease dynamics remains limited. This study characterized pathogen-associated groups, quantified disease incidence and population-level severity, and documented symptom development in plants derived from farmer-saved seeds. Seven field plots comprising 341 living plants were surveyed; symptomatic tissues were examined by direct microscopy and targeted PCR/RT-PCR, and 150 seedlings followed by 80 transplanted plants were evaluated in a grow-out assessment. Black shank was predominant, with incidence of 2.00-40.00% and population-level severity of 0.22-39.11%; mosaic and leaf curl incidences were 0.00-8.33% and 0.00-2.08%, respectively. Morphology supported the presence of Phytophthora sp., with morphology consistent with Phytophthora nicotianae and Alternaria-associated structures. TMV-specific RT-PCR produced an ~880-bp amplicon in 5/5 mosaic-symptomatic samples, whereas begomovirus-targeting PCR produced an ~657-bp amplicon in 4/5 leaf curl-symptomatic samples. No target disease-like symptoms occurred during the nursery stage. After transplanting, black shank-like symptoms occurred in 34/80 plants (42.50%) at 14 DAP and 57/80 plants (71.25%) at 21 DAPs. Because amplicons were not sequenced and grow-out symptoms were not laboratory-confirmed, these findings do not establish pathogen prevalence, begomovirus species identity, or seed transmission. They provide baseline information for disease diagnosis and broader epidemiological studies.]]>
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