Efficacy of plant extracts and extracting agents against Colletotrichum gloeosporoides of pawpaw fruits

Pawpaw ( Carica papaya L.) is a fruit crop of economic importance in Kenya, where small scale farmers are the major producers. One factor limiting pawpaw production is anthracnose disease caused by Colletotrichum gloeosporoides, whose management on farm still remains a major challenge. The objective of this study was to determine the efficacy of plant extracts and extracting agents for controlling anthracnose disease on pawpaw fruits. In vitro spore germination and in-vivo tests were done using extracts from five plants; Aloe chiliensis, Azadiracta indica , Carissa edulis , Fuerstia africana and Solanum incanum ; and extracting agents methanol, chloroform and ethanol against the fungus. A logistic regression model was used to estimate the botanicals\u2019 dose response treatment ranges. The efficacy of the crude extracts was greatest when methanol was used for extraction. The highest inhibition was recorded in pawpaw fruits treated with leaf extracts of F. africana. There were significant differences in effects among treatments by methanolic extracts of the five plants on conidial spore germination percentage. Aloe chilensis (Aloe) showed a higher spore germination of 35.7%; while Azadirachta indica (Neem) resulted in the lowest spore germination of 1.2%. There were significant differences in days to healing of C. papaya fruits infected with anthracnose. Pawpaw infected fruits healed fastest (3.5 days) when treated with the methanolic leaf extracts of F. africana; while A. chiliensis ethanolic leaf extracts resulted in the longest healing time of over 7 days. Although these botanical fungicides present high potentials or controlling anthracnose pathogens of pawpaw fruits, their suitability for application within the socio-economic framework of Kenyan small-scale producers still remains a matter for further investigation.La papaye ( Carica papaya L.) est une culture fruiti\ue8re d\u2019importance \ue9conomique au Kenya, o\uf9 les petits agriculteurs sont les principaux producteurs. Un facteur limitant de la production de papayes est la maladie de l\u2019anthracnose caus\ue9e par Colletotrichum gloeosporoides , dont la gestion au champ reste encore un d\ue9fi majeur. L\u2019objectif de cette \ue9tude \ue9tait de d\ue9terminer l\u2019efficacit\ue9 des extraits de plantes et des agents d\u2019extraction pour contr\uf4ler la maladie de l\u2019anthracnose sur les fruits de papaye. La germination des spores in vitro et des tests in vivo ont \ue9t\ue9 r\ue9alis\ue9s en utilisant des extraits de cinq plantes; Aloe chiliensis, Azadiracta indica , Carissa edulis , Fuerstia africana et Solanum incanum ; et les agents d\u2019extraction m\ue9thanol, chloroforme et \ue9thanol contre le champignon. Un mod\ue8le de r\ue9gression logistique a \ue9t\ue9 utilis\ue9 pour estimer les rang\ue9es de traitement dose-r\ue9ponse des plantes. L\u2019efficacit\ue9 des extraits bruts \ue9tait la plus \ue9lev\ue9e lorsque le m\ue9thanol \ue9tait utilis\ue9 pour l\u2019extraction. L\u2019inhibition la plus \ue9lev\ue9e a \ue9t\ue9 enregistr\ue9e dans les fruits de papaye trait\ue9s avec des extraits de feuilles de F. africana. Il y avait des diff\ue9rences significatives dans les effets entre les traitements par extraits m\ue9thanoliques des cinq plantes sur le pourcentage de germination des spores conidiennes. Aloe chilensis (Aloe) a montr\ue9 une germination des spores plus \ue9lev\ue9e de 35,7%; tandis qu\u2019Azadirachta indica (Neem) a entra\ueen\ue9 la plus faible germination des spores de 1,2%. Il y avait des diff\ue9rences significatives dans les jours de gu\ue9rison des fruits de C. papaya infect\ue9s par l\u2019anthracnose. Les fruits de papaye infect\ue9s gu\ue9rissaient le plus rapidement (3,5 jours) lorsqu\u2019ils \ue9taient trait\ue9s avec les extraits de feuilles m\ue9thanoliques de F. africana; tandis que les extraits de feuilles \ue9thanoliques d\u2019A. chiliensis ont donn\ue9 le temps de gu\ue9rison le plus long de plus de 7 jours. Bien que ces fongicides botaniques pr\ue9sentent des potentiels \ue9lev\ue9s ou contr\uf4lent les agents pathog\ue8nes de l\u2019anthracnose des fruits de papaye, leur aptitude \ue0 \ueatre appliqu\ue9e dans le cadre socio-\ue9conomique des petits producteurs de Kenya reste encore \ue0 \ue9tudier

Genetic Variability Among Fusarium udum Isolates From Pigeonpea

Thirty-eight isolates of Fusarium udum obtained from pigeonpea ( Cajanus cajan ) plants showing wilt symptoms were collected from various districts in Kenya and tested for variability in vegetative compatibility groups (VCG) and amplified fragment length polymorphism (AFLP). Nitrate non-utilising mutants were generated from F.udum isolates by selecting chlorate-resistant sectors on minimal medium amended with 15gl -1 potassium chlorate. All the isolates of F. udum were grouped into a single VCG (VCG 1) with two subgroups VCG1 I and VCG 1 II. The DNA of the fungal isolates was extracted using CTAB method. The AFLP analysis of 38 isolates using seven primer combinations generated a total of 318 fragments with 102 being polymorphic (32% polymorphism). The isolates could be grouped into one AFLP group with more than ten subgroups based on the analysis of the banding patterns, although most of these subgroups were not significantly distant (<50% confidence interval) genetically. Based on VCG and AFLP, the isolates could have originated from a single lineage. The VCG and AFLP of F. udum were independent of geographical origin of the isolates

Diversidade fenotípica e patogênica de Colletotrichum, agente causal da antracnose em mangueira, e identificação de espécie

O presente trabalho teve como objetivo estudar a diversidade fenotípica e patogênica de 40 isolados de Colletotrichum obtidos de mangueira no Nordeste do Brasil e identificar diferentes espécies desse fitopatógeno, agente causal de antracnose, através da análise da seqüência da região ITS do rDNA. Quanto à caracterização morfológica e cultural, as colônias dos isolados apresentaram diversidade em relação à cor e aspecto, sendo mais comum à cor branco-cinza, característica de Colletotrichum gloeosporioides. Não foram observadas variações expressivas na morfologia dos 40 isolados. Os conídios apresentaram-se, predominantemente, hialinos e unicelulares, com formato variando de bastonete para cilíndrico. Todos os isolados produziram apressórios variados em formato e quantidade e apenas 10 isolados apresentaram setas. Para efeito do crescimento micelial e taxa de crescimento foi possível classificar os isolados em sete grupos. Vinte e dois isolados exibiram taxa de crescimento >10mm/dia, considerada típica da espécie C. gloeosporioides. Os isolados foram patogênicos em folhas destacadas de mangueira, induzindo sintomas de antracnose, na forma de manchas escuras levemente deprimidas, e apresentando variações quanto à agressividade. Na identificação específica, baseada na análise da seqüência ITS do DNA ribossomal, 36 isolados amplificaram com o oligonucleotídeos CgInt, específico para C. gloeosporioides e o ITS4, Os isolados CM1, CM4, CM5 e CM10, não amplificaram produtos para nenhum dos oligonucleotídeos específicos, sendo identificados como Colletotrichum spp. Os resultados desse trabalho demonstraram que isolados de Colletotrichum, obtidos de mangueira, apresentam ampla variabilidade morfofisiológica e patogênica. E que, possivelmente, existe mais de uma espécie de Colletotrichum que causa antracnose em mangueira no Nordeste do Brasil

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

Background: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. Methods: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. Results: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. Conclusions: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Medical Research Council of South Africa gran