The present invention relates to a cylindrical injector for the trees irrigator laid under the surface of the soil with depth 10 cm to 100 cm near the roots of the trees to deliver the water to the roots of the trees directly by injection and filtration without passing of water on the surface of the soil, wherein said cylindrical injector prevents the vegetation, reduces the salinity and protect itself from entering of the roots in it and could be maintained without digging the soil.