Identification of the causal agents of guava scab disease (GSD) and evaluation of the control efficacy of Bacillus amyloliquefaciens to GSD
Journal
Journal of Agriculture and Food Research
Journal Volume
24
Start Page
102329
ISSN
2666-1543
Date Issued
2025-12
Author(s)
Xu, Ya-Zhen
Chang, Tao-Ho
Huang, Siang-Shan
Chang, Tsai-De
Lin, Yi-Jia
Tsai, Shang-Han
Lin, Ying-Hong
Abstract
Guava scab disease (GSD), which significantly impacts fruit yield during growth and post-harvest storage, was historically attributed to Pestalotiopsis psidii; however, recent taxonomic revisions have reclassified Pestalotiopsis species into the genera Neopestalotiopsis and Pseudopestalotiopsis. In this study, symptomatic guava tissues were collected from infected orchards in southern Taiwan for pathogen isolation and identification. Samples comprised diseased leaves, fruits, and branches of guava cv. Jen Ju Pa. Based on morphological observations and multilocus phylogenetic analyses, the causal agents of GSD in these fields were identified as Neopestalotiopsis spp., closely allied with N. cubana and N. protearum. Due to increasing concerns over fungicide resistance and environmental sustainability, we also explored biological control as an alternative strategy. Three endospores-forming bacteria strains (PM-SSH-B009, PM-SSH-B018 and PM-SSH-B060) were isolated from rhizosphere soil of local orchids in southern Taiwan and identified as Bacillus amyloliquefaciens by 16S rDNA sequencing. For PM-SSH-B009 and PM-SSH-B018, the gyraseA (gyrA) sequencing provided additional resolution consistent with B. amyloliquefaciens; however, gyrA could not be resolved for PM-SSH-B060. In vitro assays demonstrated that these strains significantly inhibited the mycelial growth and spore germination of Neopestalotiopsis spp., causing abnormal swelling of germination tubes and hyphae. On detached fruit, three application timings were compared to assess practical efficacy. Co-inoculation and pre-inoculation with PM-SSH-B018 or PM-SSH-B060 reduced GSD severity, whereas post-inoculation was less effective. These findings support B. amyloliquefaciens as a promising component of integrated GSD management, and provide a foundation for subsequent studies to resolve the underlying antifungal mechanisms and optimize field deployment.
Subjects
Agricultural management
Bacillus amyloliquefaciens
Biological control
Food production
Phylogenetic analysis
Publisher
Elsevier BV
Type
journal article