Reaction of Selected Kenyan Bean Cultivars to Phaeoisariopsis griseola

Pathogenic variation of Phaeoisariopsis griseola in Kenya was investigated. Nineteen isolates from different regions in the country were studied on a set of 10 Kenyan bean cultivars and also on 9 differential cultivars recommended by Centro International de Agriculture Tropical (CIAT). The first trifoliate leaf was inoculated with a spore concentration of 2 × 104 spores/ml and plants were evaluated for disease reaction two weeks after inoculation. Disease reaction was classified using CIAT scale. Differences were found in virulence among isolates. Eleven pathogenic groups were identified from fifteen isolates. Kenyan bean cultivar GLP 24 and GLPX 1231 were highly resistant to P. griseola isolates used whereas cultivar GLPX 1127(a), GLPX 1129 and GLPX 1159 were susceptible to all isolates. CIAT differential cultivars RAB 206 and BAT 1647 were resistant to all the isolates of P. griseola used in this study. Key Words: Angular leaf spot, foliar disease Journal of Tropical Microbiology Vol.1(1) 2002: 2-

Biological Control of Fusarium Wilt of Tomato – A Review

Fusarium wilt of tomato (Lycopersicum esculentum) caused by Fusarium oxysporum f.sp. lycopersici leads to high losses of tomatoes in many countries. Increasing restraints on the use of pesticides encourages adoption of use of alternative strategies of controlling the disease. Alternative strategies include use of biocontrol agents. Bacterial biocontrol agents with promising biocontrol activities against F. 0xysporum f. sp. lycopersici include Pseudomonas flourescens, P. putida, P. chlororaphis, P. alcaligenes, Bacillus subtilis, Streptomyces pulcher, S. canascens, S. citreoflourescens, S. corchorusii and S. mutabilis. Fungal biocontrol agents that are efficacious against F. oxysporum f.sp. lycopersici include Penicillium oxalicum, P. purpurogenum, Trichoderma harzianum, T. piluliferum, Pythium oligandrum, non-pathogenic Fusarium oxysporum Fo47 and Trametes versicolor. Biological control agents including bacteria and fungi have shown some promise for the control of Fusarium wilt of tomato. This paper discusses the mode of action of non-pathogenic strains of F. oxysporum, other fungi and bacteria including fluorescent pseudomonads in the management of Fusarium wilt of tomato. The relative importance of systemic induced resistance in the suppression of Fusarium wilt is discussed. Key Words: biocontrol, induced resistance, rhizosphere, tomato wilt. J. Trop. Microbiol Vol.1 2002: 74-7

A REVIEW OF AGRICULTURAL AFLATOXIN MANAGEMENT STRATEGIES AND EMERGING INNOVATIONS IN SUB-SAHARAN AFRICA

ABSTRACT Aflatoxins are highly carcinogenic secondary metabolites produced by Aspergillus flavus, A. parasiticus and A. nomius. Aflatoxin contamination of food and animal feeds is, therefore, a major food security, food safety, trade, human and domestic animal health concern. Researchers worldwide have suggested various agriculture-based strategies to manage aflatoxigenic Aspergillus species and reduce contamination to safe levels. This paper reviews various agricultural strategies that could be employed to reduce contamination of aflatoxins in food crops and animal feeds, as well as the challenges faced by these reduction strategies. Among these strategies are innovations like Aflasafe TM and solar grain driers. It is hoped that this critique will stimulate refinement of the existing aflatoxin control approaches and innovations to maximize their efficacy

Efficacy of onion (Allium cepa l.) and garlic (Allium sativum l.) juice against common pathogens associated with meat

Meat contains high nutrients that make it get spoilt readily and currently used preservatives like soluble nitrites are carcinogenic. The aim of this study was to evaluate the efficacy of Onion (Allium cepa L.) and Garlic (Allium sativum L.) juice as alternative preservatives. Efficacy of the single preservatives an d their combinations was determined by the disk diffusion method against the following four meat pathogens; Bacillus subtilis (ATCC 6633), Salmonella typhi (ATCC 2202), Staphylococcus aureus (ATCC 20591) and Escherichia coli (ATCC 25922) at 0.2 g of meat. Accelerated shelf life of meat was established by determining the number of microorganisms at an interval of 1 - 2 h. The results indicated that garlic was significantly, more effective (P ≤ 0.05) in inhibition of meat pathogens than all the other test treatments. Garlic juice reduced Gram positive pathogen, Staphylococcus aureus and Bacillus subtilis to 0 by the 12th h. These results are an important reference that confirms the use of Garlic to control common pathogens associated with meat.Keywords: Garlic (Allium sativum L); Onion (Allium cepa L); Inhibition zones, Efficacy; Meat

Inoculation of tomato seedlings with Trichoderma harzianum and arbuscular mycorrhizal fungi and their effect on growth and control of wilt in tomato seedlings

A green house study was conducted to investigate the ability of an isolate of Trichoderma harzianum (P52) and arbuscular mycorrhizal fungi (AMF) in enhancing growth and control of a wilt pathogen caused by Fusarium oxysporum f. sp. lycopersici in tomato seedlings. The plants were grown in plastic pots filled with sterilized soils. There were four treatments applied as follows; P52, AMF, AMF + P52 and a control. A completely randomized design was used and growth measurements and disease assessment taken after 3, 6 and 9 weeks. Treatments that significantly (P < 0.05) enhanced heights and root dry weights were P52, AMF and a treatment with a combination of both P52 and AMF when compared the control. The treatment with both P52 and AMF significantly (P < 0.05) enhanced all growth parameters (heights; shoot and root dry weight) investigated compared to the control. Disease severity was generally lower in tomato plants grown with isolate P52 and AMF fungi either individually or when combined together, though the effect was not statistically significant (P0.05). A treatment combination of P52 + AMF had less trend of severity as compared to each individual fungus. T. harzianum and AMF can be used to enhance growth in tomato seedlings

Efficacy Of Selected Plant Extracts Against Bean Rust Disease (Uromyces appendiculatus) On French Beans (Phaseolus vulgaris L.)

In vivo evaluation of the efficacy of selected plant extracts; Neem (Azadirachta indica A. Juss) derivatives (Neem oil, Neem cake powder and Neem leaf powder) and leaf extracts of pawpaw (Carica papaya L), Tephrosia vogelii, stinging Nettle (Urtica massaica L), Tobacco (Nicotiana tabacum L.) and commercial fungicide: Kocide DF, against bean rust was conducted. The synergistic effect of known concentrations of their combinations was also evaluated. French bean variety Army that is susceptible to bean rust (Uromyces appendiculatus) was used in evaluation. Results revealed significantly (P= 0.05) high inhibitory effect on rust severity, incidence and uredospores germination by nettle, tobacco and pawpaw as single treatments and combinations of nettle, Neem oil and nettle, neem oil and pawpaw. These treatments and Kocide DF also recorded significantly (P= 0.05) high pod yields and high percentages of unblemished pods, with the exception of tobacco treatments that had high phyto-toxic effects to the plant. However, Kocide DF, nettle, neem leaf powder and all combinations had significantly (P = 0.05) high effects on plant vigour. These studies propose the inclusion of nettle, pawpaw and neem oil extracts and their combinations as natural controls of bean rust and the need for bioassay – guided research to identify new and more potent compounds in these plants.Key words: Bean rust, Natural control, Plant extracts, synergistic effect, treatments, Kocide DF

Recent advancement in modern genomic tools for adaptation of Lablab purpureus L to biotic and abiotic stresses: present mechanisms and future adaptations

Not AvailableHyacinth bean is an important traditional plant with substantial medicinal value. Being imperative, it is still less explored crop on genomic and transcriptomic scale that has indexed it as an “orphan” crop for its genome revolution. Among different crop legumes such as pigeon pea, chickpea, cowpea, soybean and common bean, hyacinth bean also serves as a significant source of nutrition for both tropical and temperate regions and execute an imperative function in fixing biological nitrogen in agriculture. Nonetheless, the productivity of hyacinth bean is restrained due to environmental and biotic cues. Thus, understanding of the genomic functions and identification of probable genes/proteins for major agronomic traits through transcriptomic approaches has become imperative to improve stress tolerance in hyacinth bean. For understanding the plant stress tolerance mechanisms, the deployment of functional genomics approaches viz., proteomics and metabolomics have become imperious in breeding programs in developing countries. These approaches have been successfully used in other legume crops to create protein reference maps and their exploitation through comparative approaches can greatly enhance the research and understanding of hyacinth bean biological processes to changing environmental conditions. In this review, emerging epigenomics, proteomics, metabolomics and phenomics approaches and their achievements both in model/crop legumes are discussed. Additionally, the review also provides an overview of the applications of advanced proteomics, metabolomics and next-generation sequencing technologies in the discovery of candidate biomarkers for the development of agronomically refined hyacinth bean which may further ensure food and nutritional security under adverse climacteric conditions in developing countries.Not Availabl