Browsing by Author "Gichuru, Virginia"

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    Pathogenicity of Pythium species on hosts associated with bean-based cropping system in south western Uganda
    (Faculty of Agriculture, Department of Crop Science, Makerere University, Kampala,, 2004) Opio, Fina.; Gichuru, Virginia; Okori, Patrick.; Buruchara, Robin
    A pathosystem is a subsystem of an ecosystem and is characterised by the phenomenon of parasitism. The bean-Pythium pathosystem consists of the host (bean), the pathogen (Pythium) and their host-pathogen relation. Of interest is how the pathogen causes pathogenicity on other crops and beans. To investigate this, screen house experiments were set up to test the pathogenicity of Pythium species derived from bean and other crops grown in association with beans. Pathogenicity was tested on maize (Zea mays), millet (Eleusine corcana), sorghum (Sorghum bicolor), peas (Pisum satium), susceptible bean variety (CAL 96) and resistant bean variety (RWR 719). The results indicated that distinct symptoms were observed in the roots and shoots of test crop species which are characteristic of Pythium infection. For instance peas had brownish watery stems and roots Also bean-derived pathogenic Pythium spp. were found to be more virulent than Pythium spp. derived from other crop species.
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    The role of mixed cropping systems on bean root rot epidemics in south western Uganda
    (National Agricultural Laboratories Institute, 2006) Opio, Fina; Gichuru, Virginia; Okori, P.; Buruchara, R.
    In south western Uganda, beans are largely grown as intercrops with sorghum, maize, sweet potato and potato . Continuous cropping of beans, has increased bean root rot epidemics. Since some of the root rot causing organisms are known to affect other crops, there was need to investigate the role they may be playing in the current root rot epidemics. Surveys were carried out in Kabale district in order to establish the incidence of root rot on other crops grown in association with beans. Plant samples for isolation of Pythium, the main causative agent of root rot were also collected. Results indicated that potato had a high root rot incidence while maize had a low root rot incidence. Also, sorghum and peas had root rot symptoms. Out of the 142 Pythium isolates collected, 21 different Pythium species were identified by ITS-DNA sequencing. Fifteen new Pythium species not previously identified in the region were found. This study finds evidence that diverse crop species associated with beans may be playing a role in bean root rot epidemics