STATUS OF RESISTANCE AGAINST SPOT BLOTCH IN WHEAT

Wheat crops produced in warm, humid climates suffer significant production losses due to spot blotch. Spot blotch has been a severe impediment in wheat output over the past four decades, not just in north India's Eastern Gangetic Plains (EGP), but also in Bangladesh, Nepal, Brazil, and other nations. Spot blotch affects an estimated 25 million hectares of wheat land worldwide (van Ginkel & Rajaram, 1998), with roughly 40% of that produced on the Indian subcontinent (Joshi et al., 2007a), where crop losses due to spot blotch are estimated to be in the 15–25% range (Dubin & van Ginkel, 1991). The causal organism Bipolaris sorokiniana colonises the older leaves at the base of the wheat plant before moving up to the canopy's upper level (Joshi et al., 2002). Crop management, soil fertility, planting density, plant developmental stage, and meteorological conditions encountered by the host throughout later stages of the life cycle all influence disease severity (Joshi et al., 2007b).