Global positioning system based spatial and temporal distribution of new leaf curl begomovirus disease on sunflower in Northern Karnataka

Abstract

Leaf curl disease on sunflower caused by begomovirus genus of the family geminiviridae. Present investigations on field survey for disease incidence, field diagnostic symptoms and its spatial and temporal distribution in major sunflower growing parts of North Eastern Karnataka through GPS system during 2013-14, revealed that the disease was found to occur at all the stages of sunflower under field condition and exhibited symptoms such as vein thickening (enations) on abaxial surface of the leaves, upward curling and reduction in leaf size and severe discoluration of capitulum (Head) followed by bushy appearance. GPS based survey indicated that the % disease incidence varied from location to location (spatial variation) and also from season to season (temporal variation). The low incidence was noticed during Kharif condition which is ranged between 6.34-11.16, with the average incidence of 11.2%, 7.4% and 6.3% in Koppal, Raichur and Ballari districts repectively. Whereas during Rabi/summer season, high magnitude of disease noticed in many of the locations surveyed and is recorded upto 92.9 %. The GPS maps plotted based on PDI scale (0-3) represents high risk areas of the disease in Raichur and adjacent areas of Nort Eastern Karnataka and the result shows that the disease occurrence was more in rabi as compared to Kharif situations irrespective of locations. GPS survey map is an indicator to locate the nature of disease spread so as to conclude the hotspot areas.