Monday, August 2, 2010

Trichoderma as Biological Control Agent

Last time I started writing on Trichoderma a Magical Plant Health Manager. This post is in continuation to the above Topic. Today we shall be discussing here the Trichoderma as Biological Control Agent (BCA).

Weindling in 1932, for the first time implicated the role of Trichoderma lignorum in the biological control of citrus seedling disease caused by Rhizoctonia solani. Since this pioneering work, several reports on successful biocontrol by Trichoderma spp. have accumulated. T. harzianum, T. viride and T. virens are the most widely used/cited for biological control. They are reported effective in controlling root rots /wilt complexes and foliar diseases in several crops (Singh et al., 2004, 2005, 2006; Zaidi and Singh, 2004) and are reported to inhibit a number of soil borne fungi like Rhizoctonia, Pythium, Sclerotinia, Sclerotium, Fusarium spp., Macrophomina etc. and recently root knot nematode, Meloidogyne spp.

Biocontrol activity of Trichoderma is due to combination of its ability to serve as antagonist, plant growth promoter, plant defense inducer, rhizosphere colonizer and neutralizer of pathogen’s activity favouring infection.

Trichoderma as a fungal antagonist

As
an antagonist, Trichoderma may directly kill the pathogen by mycoparasitism and/or antibiosis. Also, it may adversely affect the growth of the pathogen either by antibiosis or by competing for the nutrient,oxygen or space. Indirectly, it may promoting plant growth which manifests itself as root and shoot growth. resistance to biotic and abiotic stresses and changes in the nutritional status of the plant.

In coming posts I shall be mainly concentrating on the Mechanisms of anti fungal action with following subheadings

i) Mycoparasitism/ Hyperparasitism
ii) Enzymes
iii) Antibiosis

iv) Competition and rhizosphere competence

v) Siderophore production

vi) Signal Transduction