Botryodiplodia sp. - Crops for the Future

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Figure 15: Phialides of Trichoderma sp. Figure 16: Petri-dish with a six day old Trichoderma sp. colony Trichoderma sp. colonies spread rapidly and have a loose textured mycelium which characteristically develops irregularly, with tufts or isolated patches. The mycelium has a white transparent colour. The small conidia are in general green coloured and smooth and develop after a short time of incubation. That is the reason why the mycelium is turning into green after a few days (Figure 16). 8.2 The role of mycoparasitism As aforementioned Trichoderma spp. are already used as bio-control agents against phytopathogenic fungi and bacteria. Pythium, Phytophthora, Rhizoctonia, Fusarium and Verticillium are fungi against which Trichoderma sp. have already made an impact (KORTING, 2001). The reasons for this use are certain antagonistic attributes which most fungi out of the genus Trichoderma own. The most important mechanisms are, according to WANTOCH- REKOWSKI (2004), mycoparasitism, antibiosis and competition. Trichoderma sp. are able to enter into the mycelium of other fungi. Therefore the fungi wind around the host’s mycelium and build hyphae which break into the host’s mycelium (Figure 17). In this way the antagonists are able to “suck” the hosts. Figure 17: Trichoderma harisianum parasitizes Pythium ultimum from (BENHAMOU and CHET, 1997 and WANTOCH- REKOWSKI, 2004) 22
The fungi are producing enzymes such as cellulases and chitinases which are able to destroy the cell walls of other fungi or inhibit the germination of other spores. Some Trichoderma strains compose antibiotics which can control bacterial phytopathogenics). These mechanisms are called antibiosis. According to WILKE (2001) Trichoderma provides the same compounds as plant fortifier because it produces hormones and enzymes which are supporting the growth of the cultural plant. Apart from parasitism and antibiosis Trichoderma sp. can compete with other fungi against nutrients and space. 9 Experiments 9.1 Experimental procedure The first step of the experiment which was undertaken by the author was to collect soil samples from different regions of Sri Lanka. The samples were taken from rambutan plantations and accordingly from soils straight underneath Annona trees. Afterwards Trichoderma spp. were isolated out of the soil samples. In a second step bio-assays were carried out to prove the effectiveness of the Trichoderma sp. against the pathogens, which has been isolated earlier from infected fruits. In another experiment, cross-inoculations were done to analyse whether diseased fruits of various species infect each other. Furthermore a sporulation experiment was undertaken. 9.1.1 Laboratory set-up The most important thing while working in microbiological laboratories is to work under sterile conditions. Therefore the working places and all materials, as well as the tools and some chemicals have to be sterilized. The sterilization of most of the glassware, such as petri-dishes was done in a sterilization oven. The mode of action of the oven is hot dry air sterilization, in which at 180 °C in one hour’s time most organisms are killed. Hot moist air under pressure is the mode of action of the autoclaves (Figure 18). They are used for liquid sterilizations like media and water and other utilities such as funnels, beakers and pipettes as well as for things made out of polycarbonates like the pipette-tips. Autoclaves work at a temperature of 121 °C and a pressure of 1.1 kg/cm² and need only 15 minutes for sterilization. The reason why the 23
Page 1: Control of Post Harvest Disease (Bo
Page 4 and 5: List of Figures Figure 1: The Sri L
Page 6 and 7: 1 Summary Experiments were undertak
Page 8 and 9: 3 Sri Lanka The Democratic Socialis
Page 10 and 11: 3.2 Climate The climate of Sri Lank
Page 12 and 13: valuable consultations in industria
Page 14 and 15: Rambutan trees are either dioecious
Page 16 and 17: However, the most important genus i
Page 18 and 19: 6.2.1.2 Annona muricata Annona muri
Page 20 and 21: Figure 9: Annona squamosa Figure 10
Page 22 and 23: Characteristically for this fungus
Page 26 and 27: autoclave is used for liquid steril
Page 28 and 29: Figure 21: Soil sampling in a rambu
Page 30 and 31: 9.1.4 Isolation of the pathogen Mat
Page 32 and 33: The effectivity of the BC-agent was
Page 34 and 35: Figure 29: Experimental series of a
Page 36 and 37: Two of the Trichoderma sp. with a h
Page 38 and 39: Results of the sporulation experime
Page 40 and 41: 12 References ALAM, M.S., BEGUM, M.
Page 42 and 43: ONG, P.K.C., ACREE, T.E. and LAVIN,
Page 44 and 45: Figure 36: List of bio-control agen
Page 46: Tmu III Galagedera • Mycelial gro

Botryodiplodia sp. - Crops for the Future

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