Evaluation of seed coating with certain bio-agents against damping-off and root rot diseases of fennel under organic farming system

Abstract

Native isolates of certain antagonists i.e. Trichoderma harzianum, T. viride, Bacillus subtilis and Pseudomonas fluorescens and bio-commercial preparations (Bio Zeid “T. album†and Bio ARC “B. megateriumâ€) were evaluated against fungi have been reported to attack fennel roots i.e. Fusarium oxysporum, F. solani, Rhizoctonia solani, Macrophomina phaseolina, Sclerotium rolfsii and Pythium spp. causing root rot and damping off diseases. These diseases cause economic losses in fennel yield and a wide range of other cultivated plants. The most dangerous effects of R. solani occurred due to pre- and post- emergence damping-off and root rot diseases. All tested antagonists which coating fennel seeds at the rate of 5g/kg seeds reduced the incidence of pre-, post-emergence damping off and root rot diseases. Trichoderma harzianum, T. viride and Bio Zeid “T. album were the most effective antagonists as shown by the highest plants survival and the best fennel yield under field conditions. Moreover application of these antagonists recorded the highest increase in oil amount and oil components as compared with the control. On the other hand, P. fluorescens showed the lowest effect. This trend was true during the two successive growing seasons 2015 and 2016.