Bacterial leaf spot (Xanthomonas campestris pv. mori)

 Introduction

The disease is first reported from Korea by Choi et al (1988). In India, Panday and Singh (1989 and Maji et al (1996), from West Bengal. The disease is very severe during rainy season causing huge amount of leaf loss.

Symptoms

Presence of numerous water soaked spots which initially appear on the lower surface of the leaves. Later tiny black spots appear on the upper surface of the leaves also.The leaves gradually turn brownish, and in the late stage the spots become brownish black surrounded by yellow halo around the spot. The necrotic tissues within the spot fall off forming minute holes , resulting premature leaf fall.

Causal organism

Xanthomonas campestrispv.mori

Systematic position

Description of the pathogen

The pathogen is rod shaped, motile, gram negative. The colonies in nutrient agar are small, circular, convex, slow growing yellow in colour, gelatin and are catalase positive.

Pre disposing factors

Bacterial leaf spot appear in the months of May and continue up to November with maximum severity during July. The BLS disease severity has significant positive correlation with minimum temperatures, maximum and minimum relative humidity, rainfall and number of rainy days and negative correlation with maximum temperature.

Resistant varieties

 Control

Application of agricultural antibiotics such as Agrimycin 100 ppm (safe period 14 days) or Streptomycin 0.2% or fungicide Dithane M-45 (.2%)- Safe period 14 days.

Related literature

Banerjee R,  Maji, MD, Ghosh P, Sarkar A, (2009) Genetic analysis of disease resistance against Xanthomonas campestris pv. mori in mulberry (Morus spp.) and identification of germplasm with high resistance. Archives of Phytopathology and Plant Protection 42(3): 291-297

Baqual MF, Sharma DD, Gupta VP, Chandra shekar DS, (2000) Efficacy of biocontrol agents and plant products against Pseudomonas syringae pv. mori and Xanthomonas campestris pv. mori causing bacterial blight in mulberry. Sericologia 40(3): 479-485.

Maji MD, Qadri SMH, Pal SC, (1998) Xanthomonas campestris pv. mori- a new bacterial pathogen of mulberry. Sericologia, 38(3): 519-522.

Maji MD, Qadri SMH, Pal SC, (2003) Evaluation of mulberry phylloplane microorganisms for biological control of bacterial leaf spot of mulberry caused by Xanthomonas campestris pv.mori Indian J. Agric. Res., 37 (4): 307 – 309.

Sharma DD, Gupta VP, Baqual MF, Chandrashekar DS, (2001) Efficacy of plant extracts against Pseudomonas syringae pv. mori and Xanthomonas campestris pv. mori causing bacterial blight in mulberry. Indian J. Seric 40(1): 109-111.