Assessment of Resistance in Tomato Varieties Under Greenhouse Conditions Against FusariumWilt, and Biological Control of the Disease

Tomato crown and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici and Fusarium oxysporum f. sp. lycopersici, is one of the most important disease of this crop. The disease control is mainly achieved by the use of resistant cultivars and crop rotation. Biological control is considered as a potential alternative strategy for disease management. In present study, resistance of common tomato cultivars namely Ergon, Daehnfild, Clause grown in green houses in East Aazrabayjan province were evaluated. For this purpose, three Fusarium isolates including two reference isolates (F. oxysporum f. sp. radicis-lycopersici and F. oxysporum f. sp. lycopersici) and a highly virulent local isolate of F. oxysporum were used. Resistance of cultivars was assessed based on different factors such as disease percentage, wet and dry weight of foliage, wet and dry weight of roots and the height of each plant. Based on our results, Daehnfild showed highest degree of susceptibility and F. oxysporum f. sp. radicis-lycopersici showed the highest degree of pathogenicity. Biological control of disease was evaluated by using the most virulent isolate of Fusarium and the most susceptible tomato cultivar. Two isolates of Trichoderma harzianu (Strain T22 isolated from TRIANUM-P and the second was obtained from Iranian Institute of Plant Protection)and single strains of Pseudomonas fluorescens (CHAO) were evaluated for antagonistic potential against causal fungus of this disease in laboratory and greenhouse conditions. Our results based on laboratory experiments showed that T.harzianum recovered from commercial biological control product (TRIANUM-P), together with P. fluorescens (CHAO) showed the highest degree of control in compare with control. But the greenhouse experiments revealed that the second isolate of T. harzianum showed the highest degree of control in compare with control.