Use of Beneficial Microorganisms to Minimize the Recommended Rates of Macronutrients to Control Cucumber Damping off

Abstract

Rhizoctonia solani is a major problem causing damping-off of seedlings and root rot in mature plants and thus reducing nutrient uptake and plant stand. The aim of this study is to evaluate the effect of some bioagents in combination with the lowest doses of macronutrients on management of R. solani in cucumber plants. Four cucumber hybrids, i.e. hybrid 6, hybrid 9, hybrid 14 and Beit-Alpha F1 were tested for their susceptibility to the pathogenic fungi. Data indicated that Beit-Alpha, was highly susceptible to infection by all the pathogenic fungi and R. solani isolate No.1 was highly aggressive. The double recommended dose of each of potassium and phosphorous was the most effective treatment. Half dose of phosphorous gave the lowest reduction of damping-off. T. harzianum, T. viride, a mixture of them, Bacillus subtilis and Pseudomonas fluorescens, as well as arbuscular mycorrhizal fungi (AM), were used. The maximum reduction in disease incidence was recorded due to using P. fluorescens followed by AM fungi. They significantly reduced damping-off and enhanced the vegetative growth of cucumber plants and the levels of oxidative enzymes compared to control.