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Luz, W.C. da, Stockwell, C.A., Bergstrom, G.C. 2003. Biological control of Fusarium graminearum. In: Leonard, K.J., Bushnell, W.R. (ed), Fusarium Head Blight of Wheat and Barley, APS Press, St. Paul, MN, pp. 381

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Eretmocerus siphonini Viggiani and Battaglia is one of parasitoids that showed a promising trend towards control of some whitefly species. The classical biological control of Siphoninus phillyreae (Haliday) (Homop­te­ra: Aleyrodidae) and Aleurolobus niloticus Priesner and Hosny (Homop­te­ra: Aleyrodidae) was achieved through mass rearing and releasing of E. siphonini in three governorates in Egypt during 1998-1999. A total of 237,020 parasitoids were reared and released in Assiut, Giza and Sharqiya governorates. The rate of parasitism increased from 5 to 60% and from 21 to 65% during 1999-2000, respectively, in Assiut. In Giza governorate, the increase amounted 2 to 46 and 10 to 67% on S. phillyreae on pome­gra­nate plant. Accordingly, E. siphonini showed that, it is an effective parasitoid legible for control of this whitefly. Similarly, the parasitism rates of E. siphonini increased (from 8 to 67% and 12 to 73 in Assiut and from 14 to 76 and 27 to 70% in Sharqiya) after releasing of the parasitoids on A. niloticus on ziziphus plants which showed the important role of this parasitoid in Egypt.

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We investigated alfalfa and stinging nettle from the point of view of their potential to supply natural enemies of pests for protecting greenhouse cultures. We carried out a three year long study based on sweepnetting. The most frequent predatory insect was Orius niger (Wolff) in alfalfa and nettle. This species among others has an important potential in the biological control of thrips. Among ladybugs, the most important species in alfalfa and nettle were Propylea quatuordecimpunctata (Linnaeus), Coccinella septempunctata Linnaeus and Hippodamia variegata (Goeze), which consume significant amounts of aphids. The most frequent spider family in alfalfa and nettle was Thomisidae and Philodromidae. The dynamics of their prey composition suggests that these taxa present a significant suppressive force on pests. The predator thrips Aeolothrips intermedius Bagnall that feeds on phytophagous thrips, mites and other soft-bodied arthropods was also significant in the arthropod assemblage of alfalfa. Our three-year investigation showed that the abundance and the species richness of the natural enemies of greenhouse crops are suitably high in both alfalfa and nettle stands. The number of generalist predators, natural enemies of pests, the most versatile tools of pest management reached its peak between mid-May to late June in nettle whereas due to mowing, the highest values for alfalfa were recorded from June to mid-August.

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Hermosa, M. R., Grondona, I., Diaz-Minguez, J. M., Iturriaga, E. A., Monte, E. (2001) Development of a strain-specific SCAR marker for the detection of Trichoderma atroviride 11, a biological control agent against soilborne fungal plant pathogens. Curr

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907 Sivan, A., Ucko, O., Chet, I. (1987): Biological control of Fusarium crown rot of tomato by Trichoderma harzianum under field conditions. Plant Disease , 17, 587

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An overview of the results of previous research on the effectiveness of entomopathogenic nematodes against harmful Thysanoptera species and so-far recorded entomophilic (parasitic) nematodes of the genus Thripinema is given. Probably in the near future entomopathogenic nematodes will partly substitute for insecticides in controlling thrips and other plant pests. Investigation of the mode of action and the bionomics of entomophilic nematodes will be required to improve their effectiveness in controlling thrips.

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Ascochyta blight (Ascochyta rabiei) is one of the most devastating diseases of chickpea. The biocontrol potential of fungal antagonists, Chaetomium globosum, Trichoderma viride, Acremonium implicatum were explored under in vitro and in vivo. A. implicatum isolate-1 overgrew the host mycelium and caused lysis, while A. implicatum isolate-2 produced inhibition zone. C. globosum profusely overgrew the mycelium of A. rabiei and T. viride showed overgrowth and profuse sporulation. Bioassay with culture filtrates of all the antagonists resulted in significant inhibition of pycnidiospore germination and reduction in colony development of A. rabiei. Syringe filtered culture filtrate when amended in liquid broth medium also significantly reduced the mycelial growth. Bioassay of culture filtrates under glass house conditions, although brought reduction in disease development in both pre- and post-inoculation sprays, but C. globosum was the most effective antagonist causing 73.12% reduction in disease index when used as post inoculation spray. Under in vitro conditions C. globosum caused 48.59% reduction in colony diameter and 70.86% reduction in pycnidiospore germination.

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Agricultural use of chemical pesticides has polluted the environment and resulted in resistance among the target organisms. The chemical strategies of pest control are dangerous to both the nontarget organisms in natural habitats and human health. Biological control is an attractive less dangerous possibility for controlling plant pathogens.Some methods of biological control are becoming now commercially available against plant parasitic fungi, nematods and insects. Among filamentous fungi many candidates with biocontrol potential can be found. Fungal biocontrol agents are less effective and reliable than the synthetic pesticides therefore their use in the agricultural practice requires genetic improvement.

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Study and comparison of efficiency of the antagonist species Trichoderma atroviride, T. harzianum and T. longibrachiatum against Fusarium wilt were carried out using in vitro and in vivo based bioassay. Significant decrease of both growth and conidia production of the pathogen are obtained compared to the control. Thus, the highest percentages of diameter colony reduction and conidial production were obtained with the T. atroviride isolate (Ta.13), causing 65.64% reduction in colony diameter (direct confrontation), 48.71% reduction in colony diameter (indirect confrontation), and a complete inhibition of conidial production. Once more in direct confrontation, T. atroviride overgrowth the pathogen colony and sporulate above. The seed treatment by Trichoderma spp. isolates before sowing in a soil already infested by the pathogen led to a significant decrease of disease severity compared to the untreated control. The weakest index of disease severity is obtained with the T. atroviride isolates (Ta.13), which cause 83.92% reduction compared to the control. The most effective isolates in protection chickpea seedlings against the disease were the three strains of T. atroviride species (Ta.3, Ta.7 and Ta.13) as well as the isolate T. harzianum (Th.16). Reduction of disease severity obtained was associated with an increase of the vegetal growth including the stem height as well as the plant fresh and dry weight.

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Twenty strains of Pseudomonas fluorescens were evaluated for their potential in promoting plant growth and in the control of late leaf spot caused by Cercosporidium personatum in groundnut under greenhouse conditions. Seed treatment with P. fluorescens strain Pf1 recorded the highest germination percentage and the maximum plant height. Seed treatment with P. fluorescens Pf1 significantly controlled late leaf spot disease of groundnut and increased the pod yield. When the treated seeds were sown in soil, the antagonist colonized well in the groundnut rhizosphere. P. fluorescens Pf1 showed the maximum production of indole acetic acid in in vitro.

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