Pak. J. Phytopathol., Vol. 25 (01) 2013. 15-22 15 Official publication of Pakistan Phytopathological Society Pakistan Journal of Phytopathology ISSN: 1019-763X (Print), 2305-0284 (Online) http://www.pakps.com OCCURRENCE AND PATHOGENICITY OF COMMON SCAB AND SOFT ROT POTATO IN AZAD JAMMU AND KASHMIR (PAKISTAN) Mahjabeen Anwar, Adnan Riaz*, Muhammad I. U. Haque, Sardar M. Mughal Department of Plant Pathology, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan. A B S T R A C T Potato (Solanum tuberosum L.) is an important cash and vegetable crop in Pakistan. Azad Jammu Kashmir (AJK) Pakistan being important area in potato cultivation is vulnerable to many pathological problems. Diseases like common scab and soft rot caused colossal losses in potato production. The objective of this study was the field survey of major potato growing areas in AJK and to isolate, identify and characterize bacteria. It was observed that the bacterial diseases were present in the area. The disease incidence indicated that common scab ranges between 20–70%, was severe at Muzzafarabad (70%) followed by disease at Kutan in Neelum valley and Bagh i.e., 20%, respectively. The disease incidence of soft rot range between 20-80%, disease was very severe at Bagh (80 %), moderate at most of the places and lowest at Muzzafarabad (20%). The diseased potato samples collected were subjected to various physiological and biochemical tests for identification and characterization of the pathogen. All isolates of both the bacteria were pathogenic and have shown a hypersensitive response. The results showed that both the Streptomyces scabies and Ervinia carotovora subsp. carotovora were present and established as the causal organism of common scab and soft rot of potato, respectively. The present study guides about the bacterial diseases prevalent in the area, crop losses occurring and facilitates in development of disease management strategy. Keywords: Potato diseases, Soft rot, Common scab, AJK, Pakistan. INTRODUCTION Potato (Solanum tuberosum L.) is one of the most cultivated crops, wholesome food, producing more energy and utilizable proteins, cultivated in about 140 countries more than 100 of which are located in the tropical and subtropical zones (Haase, 2008; FAO, 2009). Potato has been successfully grown in Pakistan, both in plains and hilly areas, depending upon season. It was cultivated on 149.0 thousand hectares with a total production of 3411.6 thousand tones (GOP, 2010). Potato is generally a high yielding crop, but crop is vulnerable to the attack of a number of diseases that are caused by fungi (Ashraf et al., 2012 ; Mehboob et al., 2013), bacteria, viruses (Abbas and Hameed, 2012 ; Abbas et al., 2012 ; Gul et al., 2013) and nematodes (Khalid et al., 2000 ; Parveen et al., 2013 ; Gondal et al., 2012). Among the bacterial diseases are soft rot., bacterial wilt, brown rot, ring rot and common scab (Bhatti et al., 2010). Potato growing areas in Punjab, Khyber Pakhtunkhwa, Baluchistan and Sindh (Pakistan) have been adequately surveyed and potato diseases were monitored and identified (Hafiz, 1986; Khalid et al., 2000; Bhutta et al., 2004). However, no substantial work seems to have been done on potato diseases in Azad Jammu and Kashmir (AJK) (Bhutta and Khan, 2008). This results in the reduction of potato area, prevalence of diseases, development of inoculum potential of soil borne diseases and reduction in yield (Bhutta and Hussain, 2002). In AJK, Muzzafarabad, Rawalakot, Bagh and Kotli areas, high incidence of bacterial disease (10-30%) were recorded by Bhutta and Khan, (2008). Erwinia carotovora subsp. carotovora (Van Hall) Dye, belonging to the family Enterobacteriaceae, a Gram- negative, rod- shaped, non- spore forming and peritrichously flagellated emerged as a destructive pathogen of potato in the field or during storage and cause heavy losses, throughout the world and its epidemics were reported by Kelyaniyangoda et al., (2004) in Sri Lanka. Streptomyces scabies (Thaxter) * Corresponding Author: Email: adnandani22@gmail.com © 2013 Pak. J. Phytopathol. All rights reserved.