EFFICACY OF TRICHODERMA HARZIANUM AS A BIOLOGICAL CONTROL AGENT AGAINST FUSARIUM OXYSPORUM IN TOMATOES (SOLANUM ESCULENTUM L.)
Nawu Takudzwa, Gwatidzo Odette Varaidzo, Rugare Joyful Tatenda, Gasura Edmore, Makaza William, Ngadze Elizabeth
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Fusarium oxysporum f.sp lycopersici is a soil borne pathogen of economic importance that reduces quality and quantity of tomatoes. Various fungicides have been utilized in the control of the pathogen however, resistance still remains a problem. However, biological control has been found as a promising alternative that suppresses F. oxysporum f.sp lycopersici. In vitro and in vivo experiments were carried out to determine the efficacy of Trichoderma harzianum as a bio-control agent against F. oxysporum. In the in vitro experiment, treatments (Trichoderma only, Dual culture, Fusarium only and Mancozeb) were laid in a randomized complete block design to evaluate radial mycelial growth of F. oxysporusm. Trichoderma harzianum significantly (p<0.001) reduced radial mycelium growth to 9.88 mm which is an inhibition of 86.8 % in a dual culture. On the other hand, Mancozeb (positive control) moderately reduced radial mycelium growth by 32.58% hence less effective compared to the Trichoderma treatment. Under greenhouse conditions, plants treated with 4 g T. harzianum exhibited least disease severity and incidence of 17.67 % and 43.7 %, respectively. High severity of 57.33 %, 80.67 % and incidence of 79.2 % and 85.4 %, respectively were recorded for positive and negative controls. In addition, 4 g T. harzianum treated plants recorded significantly higher plant height and total yield per plant for three weeks of harvest than the positive and negative control treatments. In conclusion, 4 g T. harzianum suppressed F. oxysporum development in tomato plants and further research can be done to study its effect on tomato plants under field conditions.