5436 Journal of Applied Sciences Research, 8(11): 5436-5444, 2012 ISSN 1819-544X This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLES Corresponding Author: Mostafa M.A. Hammam, Plant Pathology Department, National Research Center, El-Tahrir St., Dokki 12622, Giza, Egypt. E-mail:-mmahammam@yahoo.com Effects Of Some Fungi And Bacteria As Bio-Control Agents Against Citrus Nematode Tylenchulus Semipenetrans Cobb 1 Montasser, S.A., 1 Abd El-Wahab, A.E., 2 Abd-Elgawad, M.M.M., 2 H. Abd-El-Khair, 2 Faika, F.H. Koura and 2 Hammam, M.M.A. 1 Agricultural Zoology and Nematology Department, Faculty of Agriculture, Al-Azhar University, Egypt. 2 Plant Pathology Department, National Research Center, El-Tahrir St., Dokki 12622, Giza, Egypt. ABSTRACT The nematicidal effect of bacterial bio-control agents, i.e. Bacillus subtilis, Pseudomonas fluorescens and Sarratia marcescens and fungal bio-control agents, i.e. Aspergillus niger, Penicillium digitatum, Trichoderma harzianum and Trichoderma viride were examined against Tylenchulus semipenetrans in vitro and in vivo tests. In vitro tests, the effect of cultural filtrates of bio-control agents was evaluated at concentrations of S and/or S/2. All bio-control agents were found to be highly nematostatic against J 2 of citrus nematode. B. subtilis at S concentration was more effective against j 2 of nematode after 72h exposure time, since the nematode mortality % was 100.0%, 99.9% and 99.2% for B. subtilis, S. marcescens and P. fluorescens, respectively. The effect of fungal bio-agents against j 2 was less compared with bacterial bio-control agents. As nematode mortality was 97.6%, 97.0%, 89.4% and 87.8%. For T. viride, T. harzianum, P. digitatum and A. niger, respectively At S concentration after 72h exposure time. In greenhouse experiment, P. fluorescens was more effective in reducing the nematode population j 2 in soil, while B. subtilis was more effective in reducing the females and egg-masses in roots. P. fluorescens gave the highest percentage of efficacy (82.0%), followed by S. marcescens (77.9%) and B. subtilis (73.0%). T. harzianum was more effective in reducing the nematode population j 2 in soil, while T. viride was more effective in reducing the females and egg-masses in roots. T. harzianum gave the highest percentages of efficacy (91.1%), followed by T. viride (89.6%), P. digitatum (63.6%) and A. niger (60.0%). The bio-control agents also increased the vegetative parameters such as length and weight of shoots and shoots dry weight of citrus seedlings Key words: Biological control, Bacillus subtilis, Pseudomonas fluorescens, Sarratia marcescens, Aspergillus niger, Penicillium digitatum, Trichoderma harzianum Trichoderma viride, Tylenchulus semipenetrans, citrus. Introduction The citrus nematode, Tylenchulus semipenetrans Cobb, causes the disease known as slow decline, whose name refers to the gradual development of symptoms in the host and the slow rate of nematode population growth in newly replanted orchards. The citrus nematode was recorded as a pathogen attacking the roots of citrus trees in Egypt by Otiefa (1955) as well as many different countries of the world (Duncan and Cohn, 1990). Management of the citrus nematode remains difficult as no single tactic provides adequate control of the nematode (Verdejo and McKenry, 2004). Therefore, alternative methods of controlling nematode in particular by the use of microorganisms are now being widely developed and several are already being produced commercially. The bacterial and fungal bio-control agents were tested against the nematode infection by many workers. The ability of Bacillus cereus S18 was tested to control Meloidogyne incognita, Meloidogyne javanica and Meloidogyne arenaria in tomato by Mahdy et al. (2000). Bacillus subtilis, Pseudomonas fluorescens and Sarratia marcescens were able to reduce the population of root-knot nematode, M. javanica, infecting tomato plants, when tested at 100 ml broth bacterial culture adjusted to 10 8 CFU/ml. Both P. fluorescens and S. marcescens gave the most nematicidal activity against hatched juveniles of M. javanica (Abadir et al., 2004).In the greenhouse, B. subtilis, when applied as a soil drench, was the most effective in reducing the number of juveniles in soil, galls and egg masses of M. incognita on the roots of eggplant plants (El-Nagdi and Abd-El-Khair, 2008). S. marcescens and P. fluorescens were significantly reduced the incidence of root-knot disease in soil artificially infested with M. incognita, the study indicated that S. marcescens and P. fluorescens were potent as bio-control agents for controlling the root-knot nematodes (Mohamed et al., 2009). The ability of P. fluorescences strain 843 and Azospirillum brasilense strain W24 to improve Washington Navel Orange fruits quality and to control the persistence of nematode in the soil was tested by Abdelaal et al. (2010). Three types