Showing papers on "Trichoderma harzianum published in 1983"

Parasitism of Trichoderma spp. on Rhizoctonia solani and Sclerotium rolfsii--scanning electron microscopy and fluorescence microscopy.

Abstract: Elad, Y., Chet, 1., Boyle, P., and Henis, Y. 1983. Parasitism of Trichoderma spp. on Rhizoctonia so/ani and Sclerotium rolfsii- Scanning e lectron microscopy and nuorescence microscopy. Phytopathology 73:85-88. Hypha! interactions between either Trichoderma harzianum or T. hamawm, and Sclerotium rolfsii or Rhizoctonia so/ani were observed by scanning electron microscopy. Trichoderma spp. auached to the host either by hypha! coils, hooks, or appressoria. Lysed sites and penetration holes were found in hyphae of the plant pathogenic fungi, following reinoval of parasitic hyphae. High 13-(1 ,3) glucanase and chitinase activities were detected in dual agar cultures when 1: harzianum parasitized S. rolfsii,

Possible role of lectins in mycoparasitism.

Abstract: Lectin activity in a host-mycoparasite relationship was demonstrated with Rhizoctonia solani and Trichoderma harzianum. Attachment of O but not A and B erythrocytes to hyphae occurred on R. solani but not on its mycoparasite. This phenomenon, which was Ca2+ and Mn2+ dependent, was prevented by galactose, present in T. harzianum cell walls, and by fucose.

Ultrastructural Studies of the Interaction Between Trichoderma spp. and Plant Pathogenic Fungi

Abstract: The uhrastructural changes during parasitism of the biocontrol agents Trichoderma harzianum and T. hamatum, were observed under a transmission electron microscope. Electron micrographs show that during the interaction of Trichoderma spp. with either Sclerotium rolfsii or Rhizoctonia solani the hyphae of the parasites contact their host, and then enzymatically digest their cell walls. Extracellular fibrillar material is deposited between the interacting cells. Parasite organelles, e.g. mitochondria, vesicles and dark osmiophilic inclusions, accumulate in the parasitizing cells. In response to the invasion, the host produces a sheath matrix which encapasulates the penetrating hypha and the host cells become empty of cytoplasm.

Utilisation of Egyptian rice straw in production of cellulases and microbial protein: Effect of various pretreatments on yields of protein and enzyme activity

Abstract: Rice straw was chosen as a cheap carbon source for SCP production using a locally isolated fungus identified as Trichoderma harzianum. The chemical constituents of the raw material were cellulose 43%, hemicellulose 26% and relatively low lignin, 16%. The effects of chemical and physical pretreatments on the protein production, cellulase activity and cell mass of T. harzianum have been investigated. Pretreatment of the raw material using a combination of NaOH and high pressure steam treatment increased its microbial digestibility from 24% to 73%. Similar results were obtained by pretreatment with sodium chlorite for holocellulose formation. However, maximum yields of cell mass and protein were obtained by the first method. The organism gave 7.18 g litre−1 cell mass and 2.50 g litre−1 mycelial protein. Treatment with sodium chlorite increased cellulase activities but gave a lower fungal yield. When the NaOH was applied with high pressure steam, the organism produced 32.8% crude protein, a yield similar to that given by the same organism cultured on soluble carboxymethylcellulose.

Evaluation of Trichoderma spp., Fungicides, and Chemical Combinations for Control of Southern Stem Rot on Peanuts

Abstract: Field experiments evaluating three isolates of Trichoderma harzianum Rifai and a white spored Trichoderma sp. alone and in combination with fungicides and fungicide-insecticide/nematicide combinations were conducted during 1979-81 in an area with a history of high incidence of Sclerotium rolfsii Sacc. None of the Trichoderma sp. treatments alone, mixed with wheat middlings, or combined with carboxin reduced disease or increased yield over the control; however, disease was reduced when T. harzianum was applied with PCNB at 11.2 kg/ha. Trichoderma spp. appeared to be active only over a 3-8 day period, which was inadequate for control of S. rolfsii for the entire season. Treatments containing PCNB (11.2 kg ai/ha) alone or with the insecticide/ nematicides ethoprop (3.4 kg ai/ha), fensulfothion (3.4 kg ai/ha), and aldicarb (1.7 kg ai/ha) significantly increased yields 9 of 12 times with an average increase of 790 kg/ha; and significantly reduced disease loci at harvest 5 of 12 times with an average r...