Seed treatment Seed coating with Trichoderma is one of the easy and effective methods of delivering the antagonist for the management of seed/soil-borne diseases. Seed is coated with dry powder/dusts of Trichoderma just before sowing. For commercial purpose, dry powder of antagonist is used at 3 to 10 g per kg seed based on seed size (Mukhopadhyay et al., 1992).
Treating of seeds with biocontrol agents and then incubating under warm and moist conditions until just prior to emergence of radical is referred to as bioprimming. This technique has potential advantages over simple coating of seeds as it results in rapid and uniform seedling emergence. Trichoderma conidia germinate on the seed surface and form a layer around bioprimed seeds. Such seeds tolerate adverse various soil conditions better. Biopriming could also reduce the amount of biocontrol agents that is applied to the seed.
Seedling roots can be treated with spore or cell suspension of antagonists either by drenching the Trichoderma in nursery beds or by dipping roots in Trichoderma suspension before transplanting. Root dipping in antagonist's suspension not only reduces disease severity but also enhances seedling growth in rice, tomato, brinjal, chili and capsicum (Singh and Zaidi, 2002).
Foliar spraying/Wound dressing
The efficacy of biocontrol agents for foliar diseases is greatly affected by fluctuation of microclimate. Phyllosphere is subjected to diurnal and nocturnal, cyclic and non-cyclic variation in temperature, relative humidity, dew, rain, wind and radiation. Hence water potential of phylloplane microbes will be varying constantly. Khan and Sinha (2005, 2007) emphasized on the usefulness of T. harzianum and T. virens in foliar sprays and talc-based formulations for reducing disease incidence of sheath blight of rice. Though foliar application of Trichoderma reduce the severity of diseases under field conditions, it is not technically feasible due to increased dosage and economy realized from the crop. Hence, dosage and frequency of application has to be standardized based on the crop value, which could be as a reliable and practical approach.
· Khan AA, Sinha AP (2005). Influence of different factors on the effectively of fungal bioagents to manage rice sheath blight in nursery. Indian Phytopathol. 58(3):289-293.
- Khan AA, Sinha AP (2007). Screening of Trichoderma spp. Against Rhizoctonia solani the causal agent of rice sheath blight. Indian Phytopathol. 60(4):450-456.
· Mukhopadhyay AN, Shrestha SM, Mukherjee PK (1992). Biological seed treatment for control of soil borne plant pathogens. FAO Plant Protect. Bull. 40:21-30.
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