EVALUATION OF THE EFFICIENCY OF THE BIOAGENT TRICHODERMA LONGIBRACHIATUM AGAINST ROOT ROT DISEASE OF CUCUMBER PLANT CAUSED BY THE FUNGUS FUSARIUM SOLANI.

This study was conducted to evaluate the efficiency of the bioagent Trichoderma longibrachiatum in controlling cucumber root rot disease caused by Fusarium solani. The pathogenic fungus was isolated from the roots of cucumber plant infected with root rot disease. The pathogenicity of F. solani was tested in Petri dishes and it was found that it reduced the germination percentage to 50% compared to the control treatment, which was 90%. The results of dual culture showed that the bioagent T. longibrachiatum inhibited the growth of F. solani and the degree of antagonism reached 1 according to Bell scale. The results of the field experiment which conducted in the greenhouse showed that the bioagent T. longibrachiatum led to increase the germination percentage of cucumber plants, reaching 96.7%, which significantly differed from the pathogenic fungus treatment, which amounted to 63.3%. The results indicated that the bioagent T. longibrachiatum significantly reduced the percentage of disease severity to 20.33%, compared with the treatment of the pathogenic fungus F. solani alone, which reached 65.67%. bioagent T. longibrachiatum also increased the plant height significantly up to 177 cm, compared to control treatment and pathogenic fungus treatment, which were 142 and 116 cm, respectively. It was also found that bioagent T. longibrachiatum when it was interacted with the pathogenic fungus led to increase the plant height up to 167 cm, compared with the treatment of pathogenic fungi alone, which was 116 cm. Fresh and dry weight of shoot and root systems also increased significantly in the treatment of T. longibrachiatum compared to the treatment of pathogenic fungus, followed by the treatment of the interaction between T. longibrachiatum and the pathogenic fungus treatments. The results also revealed the efficiency of T. longibrachiatum in increasing plant productivity represented by the number of fruits, the average weight of the fruits and the fruit yield per plant, which were significantly differed from the pathogenic fungus treatment alone. [ABSTRACT FROM AUTHOR]