Effect of Trichoderma harzianum on tomato plant growth and its antagonistic activity against Phythium ultimum and Phytopthora capsici

Effect of Trichoderma harzianum was investigated on plant growth and inhibitory activity against Phythium ultimum and Phytopthora capsici under laboratory and greenhouse conditions. Data under lab conditions revealed that mycelial growth of both pathogens were inhibited by T. harzianum in vitro. The effect of T. harzianum on different plant growth parameters was assessed in the presence of P. ultimum and P. capsici. Fresh and dry shoot weight was reduced by both fungal strains. The fresh shoot weight was decreased by 38.8 and 44.4% in case of P. capsici and P. ultimum, respectively. T. harzianum improved the overall plant growth in the presence of P. ultimum and P. capsici. Histopathological observation of P. ultimum and P. capsici infected tissue of the root clearly indicated that both severely affected the epidermis and vascular bundle of the host plant. T. harzianum reduced the size of lesions caused by the two pathogens. Observation of hyphae interaction of the T. harzianum with pathogens demonstrated that it inhibited the entry of both pathogens to the vascular bundle of the host tissue. Furthermore, no effect was observed on the vascular bundle, pith and cortex of treated host plant inoculated with T. harzianum and pathogens.