Archivio Journal of Plant Pathology

Abstract:

Karnal bunt (KB) of wheat has become a major quarantine issue in the wake of the recent Sanitary and Phytosanitary Agreement stipulated by World Trade Organization. Under this agreement, each member country has to undertake pest risk analysis for import or export. KB infection occurs at the flowering and the disease becomes evident after harvest. Losses occur in terms of quality and for quarantine reasons. Therefore, the present study was conducted to determine the KB status for export from different grain markets of Haryana during 2001-2015, and to determine weather factors responsible for disease development to predict KB free seed/grain production area in the state. In the present investigation, maximum KB average infection of 0.501% in Yamuna Nagar and 0.269% in Palwal district of North Eastern (N.E.) zone of Haryana was observed. Whereas, in South Western (S.W.) zone, it was highest in Rewari (0.335%) district followed by Mahendergarh (0.330%). However, Fatehabad (0.025%) in S.W. zone, based on analysis of wheat grain samples during 2000-01 to 2014-2015 crop seasons, was suitable for foundation seed production as average infection of KB was < 0.05%. On discriminant analysis, 93% of original grouped cases of KB occurrence were correctly classified. Humid thermal index (HTI) ranged from 2.29 to 3.15 and rainfall 3 to 7 days enabled to induce > 0.25% KB infection at Hisar location. A significant correlation between KB infection and rainfall frequency (0.71**), total rainfall (0.65**) and HTI (0.45*) was established and these weather parameters can be used for identifying KB positive and KB negative crop seasons for certified, and foundation seed production and KB free zone/area during susceptibility period i.e. earhead emergence to anthesis stage.