Scenario of Bacterial Leaf Blight of Rice caused by Xanthomonas oryzae pv. oryzae in Major Rice Growing Regions of Karnataka

Author: Ashwini S., Vidyashankar D., Prashanthi S.K. and Shruthi Mallikarjun Kolur

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Abstract

Bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the major biotic constraints in rice production. The disease causes 20–40% yield loss at tillering stage and, overall, 50–80% yield loss in case of severity. So there is a need to understand the current occurrence of bacterial blight on rice in the major rice growing regions in Karnataka in order to develop the necessary management measures to successfully combat the disease. Roving survey was carried out in major rice growing districts of Karnataka viz., Belagavi, Davanagere, Dharwad, Haveri, Koppal, Shivamogga and Uttar Kannada during kharif 2019 to assess the rice bacterial leaf blight severity (BLB). During survey, Belagavi district recorded the highest BLB severity (45.23 %) and lesser severity of 16.86 per cent was recorded in Haveri district. Among the different varieties observed during survey, maximum mean per cent leaf blight severity was recorded in BPT-5204 (54.18%) and least mean per cent leaf blight was recorded in Navali Sali (7.69%). Among the different growth stages of the crop, the maximum bacterial leaf blight severity was noticed during panicle initiation stage (44.98%) and least severity in tillering stage (21.20%). Three biochemical tests (KOH, Starch hydrolysis and methyl red test) were conducted to characterize isolates of Xoo. All the Xoo isolates showed positive reaction to KOH and starch hydrolysis test and negative to methyl red test.

Keywords

Rice, Bacterial leaf blight, Xanthomonas oryzae pv. oryzae, Per cent disease index (PDI)

Conclusion

An intensive roving survey was carried out in major rice growing districts of Karnataka viz., Belagavi, Davanagere, Dharwad, Haveri, Koppal, Shivamogga and Uttar Kannada during kharif 2019. Belagavi district recorded the highest BLB severity (45.23 %) and least severity of 16.86 per cent was recorded in Haveri district. The maximum mean per cent leaf blight severity was recorded in BPT-5204 (54.18%) and least recorded in Navali Sali (7.69%). The maximum bacterial leaf blight severity was noticed during panicle initiation stage (44.98%) and least in tillering stage (21.20%). Three biochemical tests that were conducted to characterize 21 isolates of Xoo showed positive reaction to KOH test, starch hydrolysis and negative to methyl red test.

References

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How to cite this article

Ashwini S., Vidyashankar D., Prashanthi S.K. and Shruthi Mallikarjun Kolur (2023). Scenario of Bacterial Leaf Blight of Rice caused by Xanthomonas oryzae pv. oryzae in Major Rice Growing Regions of Karnataka. Biological Forum – An International Journal, 15(4): 393-399.