Perpetuation of <i>Alternaria solani</i> of Potato under Temperate Kashmir Valley Conditions

Abstract

The present study on perpetuation of Alternaria solani , causing early blight of potato in Kashmir valley was conducted during 2009 and 2010. The perpetuation of the fungus A. solani was studied on diseased leaves by placing the leaves on ground surface and at 20 cm depth, as well as on diseased potatoes kept in ambient store. The pathogen perpetuated as mycelium and conidia throughout winter on diseased leaves left on the ground surface and on diseased potatoes kept in ambient store. The number of spores cm -2 leaf area and the viability of spores decreased with increase in depth of placement in soil. Maximum spores production on over wintered leaves was observed during first fortnight of June during the year 2009 and 2010, with maximum number of 294 and 323 spores, respectively. However, by the first fortnight of July, the number gradually declined to 160 and 220 spores, respectively. The highest spore viability of 44.3 and 49.3 per cent in leaves on ground surface was recorded in the first fortnight of June, 2009 and 2010, respectively. In potatoes kept in ambient store the average number of spores increased upto first fortnight of June, both in 2009 and 2010, with a maximum number of 430 and 508 spores, respectively. The number then gradually declined to 216 and 263 spores, respectively, till last observation recorded in the second fortnight of July.