INCIDENCE, SEVERITY AND DISTRIBUTION OF YELLOW LEAF CURL DISEASE OF TOMATO IN KENYA

Tomato ( Solanum lycopersicum L.) is an important fruiting vegetable grown in Kenya because of its commercial and high nutritional value. Viruses are a major constraint to tomato production in tropics and sub tropics, eliciting symptoms like stunting, leaf mosaic, distortion, chlorosis, mottling, and vein clearing similar to those caused by abiotic factors. Although begomoviruses are known to cause tomato yellow leaf curl disease (TYLCD) in Kenya, there is limited knowledge on the disease status in tomato fields. The objective of this study was to determine the incidence and distribution of TYLCD in Kenya using the double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) technique. A survey was carried out in eight major tomato growing regions (259 fields) in Kenya during September to December, 2018. Presence of tomato yellow leaf curl virus was further confirmed using DAS\u2013ELISA. The disease was present across all the counties surveyed and its prevalence, incidences and severity varied across the counties and among the fields. The mean TYLCD prevalence ranged from 19.5% in Bungoma County, to 64% in Kwale County. There was significant difference (P<0.05) in disease incidences among the varieties sampled and the incidence was lower in plants grown from hybrids seed compared to conventional varieties. Mean disease severity was significant (P<0.05) and ranged from 0.18 to 2.20. Most farmers planted non-hybrid seeds. There is need for further determination of the diversity of begomoviruses infecting tomato using other techniques to provide more information towards breeding TYLCD-resistant tomato varieties.La tomate ( Solanum lycopersicum L.) est un important l\ue9gume-fruit cultiv\ue9 au Kenya en raison de sa valeur commercial et nutritionnelle \ue9lev\ue9e. Les virus sont une contrainte majeure \ue0 la production de tomates dans les r\ue9gions tropicales et subtropicales, provoquant des sympt\uf4mes tels que le rabougrissement, la mosa\uefque foliaire, la distorsion, la chlorose, la marbrure, le d\ue9gagement des veines similaires \ue0 ceux caus\ue9s par des facteurs abiotiques. Bien que les Begomovirus soient connus pour causer la maladie de l\u2019enroulement des feuilles jaunes de la tomate (TYLCD) au Kenya, les connaissances sur l\u2019\ue9tat de la maladie dans les champs de tomates sont limit\ue9es. L\u2019objectif de cette \ue9tude \ue9tait de d\ue9terminer l\u2019incidence et la distribution de TYLCD au Kenya en utilisant la technique de dosage immuno-enzymatique en sandwich \ue0 double anticorps (DAS-ELISA). Une enqu\ueate a \ue9t\ue9 men\ue9e dans huit grandes r\ue9gions productrices de tomates (259 champs) au Kenya de Septembre \ue0 D\ue9cembre 2018. La pr\ue9sence du virus de l\u2019enroulement des feuilles jaunes de la tomate a \ue9t\ue9 confirm\ue9e par DAS-ELISA. La maladie \ue9tait pr\ue9sente dans tous les comt\ue9s \ue9tudi\ue9s et sa pr\ue9valence, son incidence et sa gravit\ue9 variaient d\u2019un comt\ue9 \ue0 l\u2019autre et d\u2019une parcelle \ue0 l\u2019autre. La pr\ue9valence moyenne du TYLCD variait de 19,5 % dans le comt\ue9 de Bungoma \ue0 64 % dans le comt\ue9 de Kwale. Il y avait une diff\ue9rence significative (P<0,05) dans l\u2019incidence des maladies parmi les vari\ue9t\ue9s \ue9chantillonn\ue9es et l\u2019incidence \ue9tait plus faible chez les plantes cultiv\ue9es \ue0 partir de semences hybrides par rapport aux vari\ue9t\ue9s conventionnelles. La gravit\ue9 moyenne de la maladie \ue9tait statistiquement significative (P<0,05) et variait de 0,18 \ue0 2,20. La plupart des agriculteurs ont plant\ue9 des semences non hybrides. Il est n\ue9cessaire de d\ue9terminer davantage la diversit\ue9 des Begomovirus infectant la tomate en utilisant d\u2019autres techniques pour fournir plus d\u2019informations sur la s\ue9lection de vari\ue9t\ue9s de tomates r\ue9sistantes au TYLCD

Susceptibility of common weeds and cultivated crops in major maize growing agroecological zones of Uganda to viruses causing maize lethal necrosis disease

Maize lethal necrosis (MLN) disease is caused when maize plants become co-infected with Maize chlorotic mottle virus (MCMV) and potyviruses notably Sugarcane Mosaic Virus (SCMV). Apart from maize, little is known about susceptibility of weed species and cultivated crop species usually growing in proximity with maize to MLN viruses in Uganda. The common weeds and crop plants were mechanically inoculated with combined sap from MCMV and SCMV infected maize plants. Samples were tested for MLN causing viruses by Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS-ELISA) and Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). The weeds that were susceptible to MCMV were Digitaria abyssinica, Eleusine africana and Roetboellia cochinchinensis; while those susceptible to SCMV were Pennisetum purpureum, Panicum maximum and Roetboellia cochinchinensis. The cultivated crops were susceptible only to MCMV and included cassava (Manihot esculenta), groundnut (Arachis hypogaea) and bean (Phaseolus vulgaris). Common weeds and cultivated crops growing close to maize in Uganda have differential susceptibility to MLN causing viruses and can act as reservoirs of MLN causing viruses. It is critical to identify non-MLN hosts in cultivated crops for crop rotation and early weeding to reduce on MLN virus inoculum in cropping syste

A study of storage bruchids (Coleoptera: Bruchidae) infesting cowpeas (Vigna unguiculata (L.) Walp.) in Kenya and their control

SIGLEAvailable from British Library Document Supply Centre- DSC:DX183477 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Occurrence and Distribution of Potato Pests and Diseases in Kenya

Potato plays an important role in food security in Kenya but yields are low