Watermelon (Citrullus lanatus Thunb.) is one of the most important vegetable crops in Egypt. It's now considered as one of the cash crop besides being a lovely summer fruit. It is important to report that El- Nubaria is one of the most important producing regions for such crop, but soil-borne diseases resulting from the frequent cultivation of watermelon in the same area is a limiting factor. However, the famous varieties which are grown in Egypt are "Aswan F1 and "Tawos F1". Most varieties deteriorated as a result of the infection by disease pathogens, where land use is very intensive and farming area is small. Again to the continuous cultivation of watermelon in the same area , the problems of soil-borne diseases have been introduced, especially fusarium wilt (Fusarium oxysporum F. niveum), sudden wilt (Monosporascus cannonballus), and root-Knot nematode (Meloidogyne spp.).Such problem is, extremely, apparent under Egyptian conditions, particularly in Nubaria region. Since, common pathogens control such as crop rotation and soil fumigation are not followed strictly, practically controlling these diseases especially in the view of the coming phase-out of methyl bromide.