124 Potato J 42 (2): July - December, 2015 Potato J (2015) 42 (2): 124-129 INTRODUCTION Potato is a one of the most important non- cereal horticultural food crop of India. India ranks third in potato area (1.90 million ha) and second in production (45 million tonnes) with an average yield of 22.9 t/ha (Pandey et al., 2014). Potato is one of the major cash crops in the Nilgiris which is bestowed with such a climatic condition that is conducive for its cultivation all round the year (Ravichandran et al., 2011). However, potato cyst nematodes (PCN) Globodera rostochiensis (Woll) and G. pallida (Stone) are reported from the Nilgiri and Kodaikanal hills of Tamil Nadu and adjoining hills of Kerala and Karnataka (Prasad, 1993) which is a important pests that seriously affect the sustainable production of potato in many countries worldwide. Globally, an average yield loss of nine per cent has been estimated due to this nematode alone (Evans and Rowe, 1998). To manage this, massive chemical control measures were undertaken in the 1970s (Prasad, 2001) but it was found inadequate to keep the nematode under check for longer periods besides being expensive and environmentally hazardous. This necessitated the development of alternative control measures to bring down the population to levels that permit profitable cultivation of potato in the Nilgiris. Plants from the Brassicaceae family are reported to suppress soil borne pathogens and pests including plant parasitic nematodes when used as soil amendment and the practice of incorporating brassicaceous plant material into the soil to control soil borne organisms has been termed as biofumigation (Thoden et al., 2011). This bio-fumigant effect is obtained when compound like isothiocyanates (a hydrolysed form of glucosinolates present in all members of the Brassicaceae) are released during the breakdown and soil incorporation. These isothiocyanates are known to possess broad pesticidal activity against weeds, bacteria, fungi and nematodes (Ploeg, 2007; Reddy, EFFECT OF BIOFUMIGATION ON POTATO CYST NEMATODES R Umamaheswari 1 , Aarti Bairwa 1 , EP Venkatasalam 1 , R Sudha 1 and BP Singh 2 ABSTRACT: Potato cyst nematodes (PCN) Globodera rostochiensis (Woll) and G. pallida (Stone) hinder the sustainable production of potato in the Nilgiri hills of Tamil Nadu. It remains as a serious endemic pest of potato in this region due to intensive cultivation of potato and favourable climatic conditions. Hence, field experiments were conducted to evaluate the efficacy of bio-fumigation by incorporating chopped residues of radish, cabbage and cauliflower in potato cv. Kufri Giriraj. One set of treatments were covered with transparent polyethylene sheets for 4 weeks before planting and another set was left uncovered. The biofumigants were compared with the chemical nematicide carbofuran @ 2 kg a.i /ha. The treatments were replicated thrice in a randomized block design. The results revealed that all the treatments significantly increased the potato yield and decreased the nematode population. Incorporation of radish leaves @ 1 kg/m 2 and covering with polyethylene sheet recorded maximum growth parameters, yield (25.97 t/ha) and minimum PCN reproduction factor (Rf) 1.21. It was on par with carbofuran treatment which yielded 25.09 t/ha and PCN reproduction factor (Rf) 1.24 and was followed by cabbage and cauliflower residues covered with polyethylene sheet. KYEWORDS: Biofumigation, cyst nematode, cabbage, cauliflower, radish, polyethylene 1 ICAR-Central Potato Research Station, Muthorai, Udhagamandalam-643004, The Nilgiris, TN, India 2 ICAR-Central Potato Research Institute, Shimla-171001, Himachal Pradesh, India