This study was conducted to identify the causal agent of root and stem rot in cucumber plants grown in open sandy soil and to control it both in the laboratory and in the field using silicon and urea. The isolation and diagnosis results revealed 39 isolates associated with the disease, including the fungus Fusarium redolens. Molecular diagnosis of the most Aggressive Isolate , FR342a and FR342b, confirmed their identification as F. redolens with 100% match to global isolates. Laboratory results showed that silicon-amended culture media at concentrations of 2%, 4%, and 6% inhibited the growth of the pathogenic fungal F.redolens colony by 66-100%. where the concentration of 4%, 6% superiority with inhibition rate of 100%. In contrast, urea -amended culture media at concentrations of 0.4%, 0.6% and 0.8% achieved 100% inhibition of fungal F.redolens growth. In the field, the 4% silicon treatment was most effective, reducing disease severity to 42.65% followed by the 0.6% urea treatment, which reduced disease severity to 45.82%. All treatments provided effective disease control and positively impacted growth parameters, including branch length, number of branches, fruit count, fruit weight, and the wet and dry weights of the root system.