The efficiency of some inducing resistance chemicals (IRC) and systemic fungicides were evaluated in vitro on suppressing the germination of conidiophores of Erysiphe pisi as well as controlling powdery mildew of pea under greenhouse and field conditions. Different degrees of inhibition to the germinated conidiospores of E. pisi occurred when the tested IRC, i.e., Bion, potassium monobasic phosphate, salicylic acid and zinc sulphate and the systemic fungicides, i.e., fenarimol 12% (Rubigan), diconazole 5% (Sumi-8), deconazole 10% (Topas) and bromuconazole 10% (Vectra). The systemic fungicides were more efficient than IRC in this regard. Spraying pea plants with the tested IRC and fungicides reduced significantly the severity of powdery mildew disease, as well as, they increased plant height, number of green pods/ plant and weight of green pods/ plant compared with control treatment under greenhouse conditions. On the other hand, spraying pea plants under field conditions during 2008 and 2009 growing seasons with any of the fungicides Topas and Rubigan, each alone or in alternation with any of salicylic acid and zinc sulphate resulted in a significant decrease in the severity of the disease with significant increment in the produced green pods yield compared with the control treatment. In addition, alternations between the tested IRC and fungicides were less efficient comparing to treatments sprayed with the tested fungicides only. Meanwhile, they were more effective than those sprayed with the tested IRC only.