Abstract:
Fragaria ananassa(strawberry) is a perennial crop belonging to the family
Rosaceae. Parallel to the increase in strawberry production, various
strawberry diseases have also become common. One such is Angular Leaf
Spot (ALS), which can lead to severe losses in yield. Xanthomonas
fragariae, a Gram-negative rod, has been identified as the causative agent of
this disease. Control of ALS is currently achieved commonly through
preventive measures such as using disease-free stocks, but these may fail to
counter an established pathogen. Therefore, it is important to explore other
viable options such as the controlled use of antibiotics. In the current study,
we have isolated the causative agent of ALS in strawberries and have
evaluated the efficiency of two antibiotics for the potential control of the
pathogen. The causative agent of ALS was isolated from diseased plant
leaves that showed characteristic symptoms. Based on the colony
morphologies on nutrient agar, two isolates, namely I_1 and I_2 were
selected, and their Gram‟s reaction, motility, and selected biochemical
characteristics were evaluated for the preliminary identification of the
isolates as belonging to the genus Xanthomonas. The effect of two
commonly available antibiotics; ampicillin, and tetracycline, were tested
against the isolates using the agar well diffusion method and both antibiotics
showed an inhibitory effect against both I_1 and I_2. Using the broth
microdilution method, the Minimum Inhibitory Concentration (MIC) of
ampicillin was determined as 250 μg mL-1 and 200 μg mL-1 for I_1 and I_2
respectively, while the MIC of tetracycline for I_1 and I_2 was 300 μg mL-
1, and 250 μg mL-1 respectively. Although this study exhibited that
antibiotics, ampicillin, and tetracycline can be effectively used against the
bacterial pathogen, the practicality for large-scale use as well as the potential
environmental and health implications should also be considered before their
application.
