Evaluation of Some Biological Agents and Plant Extracts for Controlling Cucumber White Rot caused by Sclerotinia sclerotiorum (Lib) de Bary

Five Trichoderma isolates, two bacterial bioagents and six different plant extracts compared with five commercial fungicides. All materials were tested individually and in combinations bothin vitro and in vivo against white rotdisease of cucumber caused by Sclerotinia sclerotiorum. All tested bio-agents, plant extracts, and fungicides caused significant growth reduction of S. sclerotiorum. Trichoderma hamatum caused the highest reduction followed by T. viride and T. harzianum. Bacillus subtilis was better than Pseudomonas fluorescens in reducing growth of S. sclerotiorum, meanwhile, all tested biocides reduced the mycelial growth and sclerotia formation at their highest concentrations. Also, both linear growth and production of sclerotia of S. sclerotiorum were significantly reduced by all tested plant extracts compared to control. Moreover, all fungicides caused complete inhibition of growth and sclerotia formation of S. sclerotiorum. Under greenhouse conditions, T. album and T. harzianum-2 were the most effective treatments for disease management followed by B. subtilis and P. fluorescens. Neem extract was the most effective as it reduced disease incidence and disease severity and increased fresh and dry weight of shoot and root followed by onion and lemongrass extracts. Moreover, the highest reductions of disease incidence and severity were obtained in case of Bellis and Onest 70% fungicides. However, all tested commercial biocides significantly reduced white rot disease incidence and severity, as well as increased the fresh and dry weight of shoot and root. Applying the different combinations of the previous tested management methods with varietal resistance as integrated management approaches resulted in their significance in reduction of white rot disease incidence and disease severity, as well as the improvement of some growth characters.