Bioagent mediated suppression of early blight in tomato caused by Alternaria solani under greenhouse conditions
Keywords:
Alternaria solani; Bacillus;, biocontrol;, Percent Disease Index; Pseudomonas fluorescens;, tomato; Trichoderma asperellum.Abstract
Early blight caused by Alternaria solani is a major constraint to tomato productivity and requires
ecologically safer disease management options. A greenhouse experiment was conducted on tomato
cv. Kashi Aman to evaluate the suppressive potential of Trichoderma asperellum, Bacillus sp. BV-
4, Bacillus sp. BV-7 and Pseudomonas fluorescens against A. solani. Percent disease index (PDI)
was recorded at 0, 7, 14 and 21 days after inoculation. The pathogen-only treatment reached 94.67%
PDI at 21 days, indicating severe disease development. Among the pathogen-challenged bioagent
treatments, T. asperellum + A. solani recorded the lowest PDI (16.00%) and the highest disease
reduction (83.10%) over the pathogen control. Bacillus sp. BV-4 + A. solani reduced disease by
74.65%, followed by Bacillus sp. BV-7 + A. solani (63.38%) and P. fluorescens + A. solani (57.75%).
Bioagent-only treatments maintained PDI values below 2.00%, indicating biological safety under the
tested conditions. These findings identify T. asperellum and Bacillus sp. BV-4 as promising bioagents
for integrated early blight management in tomato.
