Abstract

The production of Garlic (Allium sativum L.) is threatened by white rot disease caused by Sclerotium cepivorum; which cause heavy yield losses. The development of biocontrol systems has provided an effective approach for reducing the losses and risk of environmental pollution associated with fungicides and fungicide resistance development. Therefore, the present study was carried out to evaluate the biocontrol potential of seven Trichoderma species viz., T. harzianum, T. hamatum, T. viride, T. oblongisporum, T. longibrachiatum, T. asperillum, and T. atroviride by both in-vitro and in-vivo work for their antagonistic and inhibition potential against garlic white rot pathogen. Dual culture technique was used for the radial growth of the pathogen and antagonists record. All but four isolates were highly antagonistic that they inhibited the growth and colonized the colony of the pathogen and there was statistically significant difference among those Trichoderma isolates. The overall inhibition effect of the antagonists on the pathogen‟s colony growth ranged from 43.9 to 59.3 %. Trichoderma hamatum had the highest inhibition effect (59.3%) followed by T. harzianum (53.3 %), T. oblongisporum (52.7 %), T.viride (51.8%), T. asperillum (50.2%), T. longibrachiatum (47.2%) and T. atroviride (43.9%) . Therefore, these isolates were further studied in the glasshouse condition by using single and in combination against garlic white rot. The incidence of S. cepivorum was significantly reduced in bulbs of garlic and also improved plant growth was observed in plants treated with single inoculation of T. hamatum alone followed by T. harzianum alone and in combined inoculation of T.hamatum and T. harzianum, T. oblongisporum and T. viride isolates. Plants inoculated with S. cepivorum alone showed pronounced disease symptoms with mean disease incidence of 90.5 %. Combined treatment of T.hamatum and T. harzianum isolates were significantly reduced (62.22%) the white rot disease of garlic followed by the combined inoculation of T. oblongisporum and T.harzianum and T. hamatum and T.viride. The over all reduction in the incidence of white rot was 62.22% in the treatment of T. hamatum and T. harzianum isolates followed by 53.72% for T. oblongisporum and T. harzianum. It is concluded that the tested Trichoderma isolates (T.hamatum, T.harzianum, T.oblongisporum and T.viride) have high potential to inhibit the colony growth of S. cepivorum and the results clearly pointed out that T.hamatum, T. harzianum, T .oblongisporum and T.viride isolates can reduce the severity of S. cepivorum disease in garlic. Use of these bio-control agents could be promoted as an active component of bio-intensive Integrated Disease Management Program (IDMP) under organic mode. Keywords: Garlic, Sclerotium cepivorum, Biological control, Trichoderma species..