USING OF SOME CHEMICAL AND BIOCONTROL AGENTS TO CONTROL OF CUCUMBER ROOT ROT DISEASE CAUSED BY Rhizoctona solani Kuhn

Abstract

This study aimed to isolate and identify the pathogen of cucumber root rot disease from Babylon fields. And to test the activity of some biocontrol agents against it under laboratory and lath house conditions . The results showed the presence of cucumber root rot disease in all surveyed districts of Babylon region. The results of Isolation and identification showed the presence of 4 isolates of Rhizoctonia solani fungus, the test of pathogencity for isolates showed that all isolates caused a significant reduction of cabbage seed germination percentage, most isolates of R. solani Rh2 were pathogenic and prevent seed germination completely compared to control 100 %. also the Rh 2 and Rh1 isolates affected on cucumber seed germination which was 0.0 and 16.7% respectively compared to control 100%. Trichoderma harzianum had high antagonistic ability to the R . solani with inhibitory rate 74 .8 % whereas, the Pseudomonas fluorescens and Bacillus subtilis bacteria prevented growth of fungus completely, results showed the concentrations of bacterial suspension caused high antagonistic ability against pathogen giving 100 % in 10 , 25 , and 50 % whereas, the 1% concentration was affective on fungal radial growth to 0.67 and 1.0 cm for P. fluorescens and B. subtilis respectively and inhibition rate was 88.8 and 92.5% respectively. The results showed that all biocontrol agents treatments which were included T. harzianum and the Pseudomonas fluorescens and Bacillus subtilis bacteria caused significant reduction of disease incidence and severity of cucumber root rot under lath house conditions and closed to Beltanol fungicide activity. On the other hand, all biocontrol agents which added alone to plant caused a significant increase in plant height, wet and dry weight compared to control without pathogen. These results appeared that the ability to use the biocontrol agent to cucumber root rot caused by Rhizoctona solani Kuhn as alternative method to reduce using and damages of chemical fungicides.