Perpetuation studies of pathogen Alternaria solani (Ellis and martin) in tomato crop through seed and plant debris

Perpetuation studies were conducted through both seed and plant debris.The seeds collected at harvest from diseased tomato plants (c.v Marglobe) were stored in khadi cloth bags in laboratory and assessed for the presence of the pathogen through blotter methods at monthly intervals. Tomato leaves and twigs bearing typical symptoms of early blight disease at harvest and kept separately in nylon mesh bags. The highest conidial viability 89.67 % was seen in the month of november Ist 2014. The viability showed a gradual decrease as the storage period advanced such that after six months of storage in April 2015. The conidial viability was gradually reduced as the storage period advanced such that only 18.00 per cent was recorded in April 2015. 24.66 per cent seeds showed Alternaria solani growth in November 2014. The percentage of seeds exhibiting Alternaria. solani growth showed a gradual decrease as the storage period advanced, such that the percentage of these seeds was 4.94 per cent after six months of storage in April 2015. Leaf bits exhibiting Alternaria solani growth (31.13%) was recorded in November 2014 immediately after harvest followed by those in December 2014 and January 2015 (22.4 and 14.40% respectively). Conidial count was taken from November 2014, i.e. one month after storage of leaf bits under laboratory condition, revealed that presence of 68.21 (1× 103) conidia cm2 leaf area. There was a gradual decrease in conidial count such that 29.10 per cent spore count was recorded in April 2015. The number of viable conidia was maximum (67.34%), when leaf bits were placed under ambient laboratory conditions. On soil surface, the conidial viability was 58.30 per cent whereas at 5 cm soil depth (42.10%) conidia remained viable.