Slow decline and dry root rot of citrus caused by Tylenchulus semipenetrans and Fusarium solani, respectively are serious diseases attacking many groves in Egypt. Efficacy of the bio-agents (Trichoderma harzianum, Bacillus subtilis, Streptomyces griseus and Paecilomyces lilacinus) against citrus nematode T. semipenetrans and their combination with Nemastop were studied in vitro. Such bio-agents and Nemastop were also studied under field conditions against both T.semipenetrans and F. solani infecting Washington Navel orange trees compared with control and Nemaphos. In vitro study revealed that all tested bio-agents had various degrees of effectiveness towards the juvenile's survival compared with control treatment. Meanwhile, Bio-Nematon achieved the highest percentage of mortality for T. semipenetrans (50.0%). The population and incidence of soil borne pathogens were examined after three, seven and twelve months in vivo. Results showed that all treatments led to clear significant reduction in disease incidence compared with control treatment. All bio-agents gave good effect on decreasing T. semipenetrans population and F. solani incidence for twelve months. Benefits, achieved by simultaneous application of bio-agents based on different mechanisms of actions, are discussed. A clear significant decrement in T. semipenetrans population was noticed with the combination of T. harzianum with Nemastop. Meanwhile, B. subtilis or T. harzianum reduced F. solani incidence.