Water, particularly irrigation water, is a key source for the transmission of plant-parasitic nematodes (PPNs). The objective of the current study is to assess the influence of infested soil collected from three different counties i.e., Adco, Shibin Alqanater and Baltim representing three governorates (Beheira, Qalyubia and Kafr Elsheikh), respectively.  Egypt and irrigation water from canals (Mahmudiyah, Bassousia, and Alhilmia) on the decline of guava seedlings Pasidum guajava cv. Ameriyah under greenhouse conditions for two seasons (2020-2021). Plant-parasitic nematodes detected in soil and water samples were listed. It was found that guava seedlings grown in soil infested with root-knot nematodes (Meloidogyne spp.) and irrigated with contaminated water from canals showed the lowest rate of growth parameters when compared to plants cultivated in sterilized soil and irrigated with tap water, during the two years. However, treatment by Fenamiphos with sterilized soil and irrigated with water from canal showed the least nematode population in the soil. A significant decrease in the number of galls and egg masses was also observed in the presence of the nematicide.