INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: 1560–8530; ISSN Online: 1814–9596 14–019/2015/17–3–601–606 DOI: 10.17957/IJAB/17.3.14.019 http://www.fspublishers.org Full Length Article To cite this paper: Rauf, C.A., F. Naz, I. Ahmad, I.U. Haque and A. Riaz, 2015. Management of black scurf of potato with effective microbes (EM), biological potassium fertilizer (BPF) and Trichoderma harzianum. Int. J. Agric. Biol., 17: 601‒606 Management of Black Scurf of Potato with Effective Microbes (EM), Biological Potassium Fertilizer (BPF) and Trichoderma harzianum Chaudhary Abdul Rauf 1* , Farah Naz 1 , Iftikhar Ahmad 2 , Irfan Ul Haque 1 and Abid Riaz 1 1 Department of Plant Pathology, PMAS-AAUR, Pakistan 2 Pakistan Agriculture Research Council, Islamabad Pakistan * For Correspondence: abdul.rauf@uaar.edu.pk Abstract The efficacy of soil application with microbial preparations viz. Trichoderma harzianum, effective microbe (EM) culture and biological potassium fertilizer (BPF) was evaluated for the management of soil-borne inoculum of Rhizoctonia solani the cause of black scurf of potato cv. Desiree. Soil application with three dosages of culture suspension of T. harzianum, effective microbe (EM) culture and biological potassium fertilizer (BPF) were applied in the soil to know the efficacy of these treatments in reducing the disease. Soil application with T. harzianum at the time of sowing followed by two and three dosages at 20 days intervals gave significant protection to eyes with EGI of 30.55%, SK 24.07%, SCI 36.10%, StCI 30.60%, BSDI 26.43% and YR of 35.09% against the fungus which ultimately contributed to better crop stand and increased yield as compared to inoculated control and rest of the treatments. © 2015 Friends Science Publishers Keywords: Rhizoctonia solani; Solanum tuberosum; Biomanagement; Beneficial microbes Introduction Potato (Solanum tuberosum L.) is an annual, herbaceous, dicotyledonous plant of family Solanaceae. Potato is commonly known as disease oriented problematic crop throughout the world. The management of R. solani is difficult due to its soil-borne nature. The fungus is present in most of the soils (Banville et al., 1996). Once it becomes established in a field, it remains viable there indefinitely (Agrios, 2005). Dry sclerotia of the pathogen are reported to survive up to six years when stored at room temperature (Kumar, 1976). Soil-borne inoculum of R. solani is the main cause of black scurf on potato tubers and also contributes to eyes germination inhibition, sprouts killing, stem, stolon and root damage (Hide et al., 1973; Frank and Leach, 1980). Pioneer studies on the prevalence, incidence, severity and biology of black scurf disease pathogen in Pakistan have been reported by Rauf et al. (2007a). He reported that R. solani anastomosis group 3 is the primary cause of black scurf in Pakistan, like in most parts of the world (Banville et al., 1996). The disease was found prevalent in all the eight potato production agro-ecological zones, and was the most wide spread and prevalent in zone 2, a major potato production area with 70-80% of the potatoes production in Pakistan. It comprises of Sahiwal Pakpatan, Okara, Sialkot, Jhang and Faisalabad districts of thr Punjab Province. This zone is also an important source of seed potatoes distribution to almost all the potato production areas of Pakistan. The imported and basic seed is also multiplied in this zone (Zanoni, 1991). As black scurf is soil and seed- borne disease, so the inoculum of R. solani is carried through seed tubers from this zone to all potato production zones of Pakistan, thus adding more to existing inoculum load. This continuous addition in inoculum may ultimately lead to epidemics of disease in future. Seed treatment with bio-formulations has been found better than the chemical treatments in integrated management of most of soil-borne disease of potato (Shternshis, 2002). Among antagonistic microorganisms, Trichoderma sp. was found the most capable of parasitizing R. solani in vitro. Reduced black scurf disease index compared to control together with maximum germination and yield of potato has been reported by seed treatment with T. viridae (Arora et al., 2001). However, when T. viridae was compared with T. harzianum causing black scurf of potato, T. harzianum was found the most effective in inhibiting mycelial growth (Srivastava and Singh-Kavi, 2001). It was also found the most effective in reducing disease incidence and increase in yield over control in green house studies (Hazarika et al., 2000). Mixed cultures of beneficial microorganisms named EM4 have been developed by Higa (1988; Unpublished). EM4 is a mixed solution cultures of beneficial microorganisms. The effect of EM culture has also been studied on fungal populations in soil which significantly increased the population of Trichoderma that has an antagonistic effect on R. solani, and suppressed the plant pathogenic fungi in soil. Physical properties of the soil including cultivation depth and