Rapeseed and mustard are the third most important oilseed crop in the world after soybean (Glycine max) and palm (Elaeis guineensis Jacq) in global agriculture and India is the third largest producer with a global contribution of 28.3% of cultivated area and 19.8% of production (Shekhawat et al., 2012; Bandopadhyay et al., 2013). Brassica juncea L. (Czern & Coss. ) is an important oilseed crop traditionally grown in all Indian states with particular reference to the marginal and submarginal soils of the eastern, northern and northwestern states both in pure culture and in intercrop (mixed harvest). The low temperature and humid climate of winter is a significant factor for the growth and productivity of mustard in these regions (Rathi and Singh, 2009). Despite the notable increase in productivity and production, the crop still faces multiple abiotic and biotic challenges in farmers' fields. Destructive diseases of canola mustard include those caused by fungi, bacteria, viruses and phytoplasma. Among them, Sclerotinia stem rot is the most serious fungal disease that causes maximum damage to Indian mustard (Rakesh et al., 2016). Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original EssaySclerotinia rot, or white rot, caused by Sclerotinia sclerotiorum (Lib. ) de Bary, is a cosmopolitan and destructive soil-inhibiting pathogen. The pathogen shares a broad host range comprising more than 500 plant species comprising 278 genera in 75 dicotyledonous and several monocotyledonous plant families (Boland and Hall, 1994; Willetts and Wong, 1980; Purdy, 1979; Steadman , 1983; Sharma, 2014; Sahara and Mehta, 2008; Sclerotinia stem rot, however, occurs more frequently in cool and humid regions (Purdy, 1979; Saharan and Mehta, 2008). in temperate and subtemperate zones of the world. It has been reported to cause significant yield reduction in economically important crops (Boland and Hall, 1998; Fernando, 2004; Malvarez et al., 2007; Parveen et al., 2007). extensive literature on various aspects related to S. sclerotiorum to different crop plants, but its information on rapeseed mustard related to the present study is reviewed here in the following paragraphs Pathogen: Sclerotinia rot or white stem rot of mustard is caused by a homothallic, non-sporic fungus present in the soil, namely Sclerotinia sclerotiorum (Bolton et al., 2006). The pathogen was first described by Madame MA Libert (1837) as Peziza sclerotiorum. Later in 1870, Fuckel created a new genus Sclerotinia and renamed it Sclerotinia libertinia. Whetzel in 1945 proposed a new family Sclerotiniacae and also provided the key to the diagnosis of the genera to which it belongs. However, the name and authority for the fungus have been generally accepted as Sclerotinia sclerotiorum (Lib.) de Bary due to de Bary's significant contributions in his literature. S. sclerotiorum is a necrotrophic pathogen, including hyaline, septate, branched and multinucleated hyphae; the mycelium may appear white to light brown in culture plates (Boltan, Thomma, & Nelson, 2006). The pathogen undergoes four phases in its life cycle viz. sclerotia, apothecia, ascospores and mycelium (Purdy, 1979). It may consist of a thick mycelial carpet in narrow colonies, which subsequently produces white mounds of mycelium, covered with small liquid droplets, these mounds subsequently merging together to form dark-coloured structures, i.e.sclerotia, which are resistant to environmental stresses (Willetts and Wong, 1971 ), and also serve as primary survival structures (Coley-Smith and Cook 1971; Willetts and Wong 1980). The fungus spends 90% of its life as dormant sclerotia (Adams and Ayers 1979), the sclerotia can survive in one or more of three modes, namely myceliogenic, corpusgenic and sporogenic, but corpogenic and myceliogenic germination occurs in S. sclerotiorum (Tourneau, 1979). The germinative sclerotia give rise to 2-5 dichotomously branched columnar structures, stipes or primordials. Apothecia initially arise in the cortex or medulla as clusters or nests of intertwined, brown to hyaline hyphae, and minute, brownish, funnel-shaped cups or apothecia measuring 6–9 mm in diameter are produced at the tips. They are generally borne 6-10 mm above the soil surface and become darker in color with age. The apothecia contain cylindrical asci, measuring 108-153 x 45-10 microns. Each ascus forms eight unicellular, ovate hyaline ascospores, measuring 7 to 16 x 3.6-10 microns. These ascospores are expelled violently through the apical pore of the ascus and help in the spread of the disease during the harvest season. Initiation of the disease cycle occurs via the sclerotia, a dormant multihyphal structure that can tolerate a wide range of adverse weather conditions for several years. The germination method depends on environmental conditions (Saito, 1973; Joens, 1974; Kosasih and Willetts, 1975; Steadman, 1983; Sharma and Meena, 2011; Willets and Wong 1980) and crop canopy (Bardin and Huang 2001). Crop infection is associated with senescing flowers, which provide an energy source for ascospore germination (Cook et al. 1975), suggesting that crop phenology plays a significant role in the onset of this disease in some crops ( McLean 1958; Natti 1971; The pathogen survives (overwinters) in the soil and also in the host through the hard dormant structure, i.e. the sclerotia. It is made up of a light-colored inner part called the pith and a black outer protective covering known as the crust. The rind is highly resistant to degradation due to the presence of melanin; sclerotia enclose fungal cells that contain abundant -glucans and proteins. In S. sclerotiorum, the development of sclerotia can occur in three distinct stages (Townsend and Willetts, 1954): (i) Initially, the formation of small mounds, i.e. intertwined hyphae developed due to repeated branching of long areal primary hyphae. (ii) Development, increase in size and (iii) Finally, the sclerotia mature, characterized by the appearance of dark-colored or melanized, internally consolidated hard structures, which can often bear droplets at maturity. Both morphological and biochemical differentiations accompany these phases. All stages of sclerotia development stages are influenced by numerous factors such as photoperiod temperature, aeration and nutritional status, etc., the production of growth hormones such as oxalic acid (OA) may show a certain extent correlate with development and play an essential role in the development of the disease (Zhou and Boland, 1999; Chet and Henis, 1975; Donaldson et al., 2001). Sclerotial development is a complex, multistage process believed to be regulated by signal transduction pathways such as MAPK and PKA (Rollins and Dickman, 1998; Chen et al., 2004; Chen and Dickman, 2005; Harel et al., 2005;). Kafadar and Cyert, 2004 reported that two other pathways, namely calcineurin – MAPK and calcineurin – PKA, are also associated with the pathogenicity of this pathogen. Germination of overwintering sclerotia can be of three types depending on weather conditions. Germination.