A trial study was conducted to evaluate the impact of using magnetized sea water MSW on the adult emergence of E. zinckenella and to monitor the effect of MSW on M. incognita infecting cowpea plant. A total numbers of E. zinckenella pupa were incubation on plastic containers including soil irrigation with MSW in three concentrations. Although results indicated that, the magnetic concentrations were low, the mortality rate of the E. zinckenella pupa was high on the other hand, when the concentrations increased, the total mortality was increased. Total mortality of pupal stage was 13.75 %, 32.5% and 41.25 %, respectively when, using of magnetic sea water in concentrations 10, 20 and 40 ml.t compared with untreated treatment.In addition, this experiment was carried out to evaluate the effects of magnetizing irrigation water on naturally growing of cowpea infected with root-knot nematode M. incognita in sandy soil at three concentrations 10, 20 and 40 ml.t. The obtained results indicated that irrigation cowpea plants with magnetic water induced positive significant effect on the most of studied parameters. The percentage improvement ranged between 63.33, 78 and 97.97, 94.59 in fresh and dry weight.