Morphological Characterization of Xanthomonas arboricola causing bacterial Leaf Spot of Almond (Prunus dulcis) and its in vitro Management
DOI:
https://doi.org/10.55627/pbulletin.005.01.1939Keywords:
Bacterial spot, Almond, Xanthomonas, Antibiotics, managementAbstract
Almond (Prunus dulcis) is a high-value nut crop of considerable nutritional and commercial importance for orchard growers in the region. Bacterial spot, caused by Xanthomonas arboricola pv. pruni, produces foliar necrosis, fruit blemishes and defoliation that reduce yield and marketability in the study region. A total of 290 symptomatic leaf samples were collected from commercial orchards in Quetta and Pishin, transported under cooled conditions and processed for isolation and purification; a subset yielded culture-confirmed X. arboricola pv. pruni isolates that were identified by typical mucoid yellow colony morphology and fulfillment of Koch’s postulates through pathogenicity and re-isolation. in vitro susceptibility was assessed by standardized disc-diffusion assays: four antibiotics (tetracycline, tetracycline HCl, oxytetracycline and streptomycin sulfate) at 100–300 ppm were tested; zones of inhibition were recorded at 24, 48, 72 and 96 hours (h) with triplicate replication and analyzed by two-way ANOVA with Tukey’s HSD. Results showed dose- and time-dependent inhibition: oxytetracycline gave the strongest chemical activity (maximum zone 34.8 mm at 300 ppm, 72 h) while streptomycin was least effective. It was concluded that oxytetracycline is the best amongst the all applied antibiotics and recommended for in vitro management of Xanthomonas pathogen causing Bacterial spot of Almond moreover it is suggested that greenhouse and small-plot field trials on resistance assessments for antibiotics, and a large-scale, multi-season study to validate efficacy, safety and regulatory compliance before operational adoption of these antibiotics.
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Copyright (c) 2026 Shair Ali, Zobia Jabeen, Muhammad Waris, Ghulam Rasool, Syed Zulfiqar Ali, Basheer Ahmed, Naeemullah .
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