Study the mechanisms of parasitism and antagonism of different biocontrol agents against Sclerotinia sclerotiorum, the causal organism of white rot disease on eggplant in the laboratory

Abstract EN

Testing the parasitic ability of different species of the biocontrol agents by the use of dual culture technique revealed high Inhibition of Trichoderma harzianum1 reached 1 followed by T.harzinum2 and 3 , T.viride ,T.ressei,Ulocladium atrum and Fusaium laterium, while T.longibrachium appeared to have weak parasitic capability which reached 4.

When the pathogen S.sclerotiorum was cultured at the center of the petridish ,the isolates 1 and 2 ofT.harzianum proved to have the best inhibition ability to the pathogen by the ratio of 100% .All the tested isolated of the biocontrol agent gave high ability in producing volatile compounds, which inhibited the mycelial growth of the pathogen ,with the best of them was F.laterium (69.9%),there were no significant difference among the three isolates of T.harzianum compared to T.ressei and U.atrum in their production of volatile compounds.

HCN production by the biocontrol agents showed high ratio of all the tested antagonists except U.atrum and T.harzianum2 .When two concentrations (30 and 50%) of the culture filterate of the antagonists were added to Potato Dextrose Agar (PDA) , they inhibited the radial growth of the pathogen by the ratio of 100% except F.laterium which gave 23.7%.

The use of slide culture technique to test the mycoparasitism of the biological agents and the pathogen ,it was noticed coiling of the hyphae around the mycelial growth and penetration of the hyphae of S.sclerotiorum.