Detection and distribution of seed-borne viruses on commercial cowpea (Vigna unguiculata (L.) Walp) cultivars in Ado-odo Ota, Ogun Sate, Nigeria

Cowpea is a major source of dietary protein in the nutrition of people in sub-Saharan Africa. Many viruses have been reported to cause economic reduction in cowpea productivity in Nigeria. However, their current distribution is not well documented while most farmers source their seeds from local markets. This study investigated the detection and distribution of seed-transmitted viruses on commercial cowpea cultivars in Ado-odo Ota Local Government area (LGA) of Ogun State. Cowpea seed samples were collected from eleven markets in the LGA. Coordinates of the locations were recorded with Geographical Positioning System (GPS). Thirty cowpea seeds from each market were sowed in planting pots under screenhouse conditions and seedlings were observed weekly for visible virus symptoms. Four-week old seedlings were tested for viruses using Antigen Coated Plate-Enzyme-Linked Immunosorbent Assay (ACP-ELISA) and Reverse Transcription Polymerase Chain Reaction (RT-PCR). Samples were tested for seven seed-transmitted viruses namely Blackeye cowpea mosaic virus (BlCMV), Cowpea aphidborne mosaic virus (CABMV), Cucumber mosaic virus (CMV), Southern bean mosaic virus (SBMV), Cowpea mottle virus (CMeV), Cowpea yellow mosaic virus (CYMV) and Cowpea mild mottle virus (CPMMV). Seed germination rates ranged from 63.3±15.3% of seeds from Joju to 96.7 ±5.8% for Atan and Iju markets. All samples tested negative to ELISA and were confirmed negative by RT-PCR. These findings suggest absence of seedtransmitted cowpea viruses in the study area as at the time of sampling. Periodic detection survey is recommended to assure the virus-free status of the area.Keywords: ACP-ELISA, Cowpea viruses, Diagnostics, RT-PCR, Seed transmissio

Incidence of leaf blight disease of Egusi melon in South-west Nigeria

Egusi melon ( Citrullus lanatus (Thumb) Mansf.) is an important vegetable crop grown for edible seeds and oil in West Africa. Leaf Blight Disease (LBD) is one of the major constraints to its production, with potential to cause economic damage. The objective of this study was to investigate the incidence and distribution of leaf blight on Egusi melon in Southwestern Nigeria. A survey of LBD of Egusi melon was conducted in 2015 and 2016, in five southwestern States of Nigeria (Ogun, Oyo, Osun, Ekiti and Ondo States). Twenty plants each, were randomly sampled from 150 farms comprising 30 farms each, from each State. The distribution of different Egusi melon varieties planted was recorded. \u201cBara\u201d cv. was the most cultivated variety (51.6%); followed by \u201cBojuri\u201d (30.4%) and \u201cSerewe\u201d (18%). Leaf blight was observed in most farms in the five States, from 73% in Osun and Oyo states to 83% in Ondo State. Disease incidence and severity varied with locations and cultivars, and ranged from 0.0-87.5\ub118% and 1.0\ub10-4.5\ub10.8 in Osun State to 20.0\ub119 - 95.0\ub14.5% and 2.3\ub11.5 - 5.0\ub10 in Ondo State. Out of the twelve fungal pathogens from ten genera isolated from infected plants, only Colletotrichum truncatum , C. gloeosporioides and Lasiodiplodia theobromae caused Leaf blight on Egusi melon.Le melon Egusi ( Citrullus lanatus (Thumb) Mansf.) Est une importante culture l\ue9gumi\ue8re cultiv\ue9e pour les graines et l\u2019huile comestibles en Afrique de l\u2019Ouest. La maladie de br\ufblure foliaire (LBD) est l\u2019une des principales contraintes \ue0 sa production, avec le potentiel de causer des dommages \ue9conomiques. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9tudier l\u2019incidence et la distribution de la br\ufblure foliaire du melon Egusi dans le Sud-ouest du Nig\ue9ria. Une enqu\ueate sur la LBD du melon Egusi a \ue9t\ue9 faite en 2015 et 2016, dans cinq \uc9tats du sud-ouest du Nig\ue9ria (\uc9tats d\u2019Ogun, Oyo, Osun, Ekiti et Ondo). Vingt plantes dans chaque \uc9tat ont \ue9t\ue9 \ue9chantillonn\ue9es au hasard dans 150 fermes comprenant 30 fermes chacune, de chaque \uc9tat. La distribution des diff\ue9rentes vari\ue9t\ue9s de melons Egusi plant\ue9es a \ue9t\ue9 enregistr\ue9e. \uabBara\ubb cv. \ue9tait la vari\ue9t\ue9 la plus cultiv\ue9e (51,6%); suivi de \uabBojuri\ubb (30,4%) et \uabSerewe\ubb (18%). La br\ufblure foliaire a \ue9t\ue9 observ\ue9e dans la plupart des exploitations agricoles des cinq \uc9tats, passant de 73% dans les \uc9tats d\u2019Osun et d\u2019Oyo \ue0 83% dans l\u2019\uc9tat d\u2019Ondo. L\u2019incidence et la gravit\ue9 de la maladie variaient selon les emplacements et les cultivars, et allaient de 0,0-87,5 \ub1 18% et 1,0 \ub1 0-4,5 \ub1 0,8 dans l\u2019\uc9tat d\u2019Osun \ue0 20,0 \ub1 19 - 95,0 \ub1 4,5% et 2,3 \ub1 1,5 - 5,0 \ub1 0 dans l\u2019\uc9tat d\u2019Ondo . Sur les douze agents pathog\ue8nes fongiques de dix genres isol\ue9s de plantes infect\ue9es, seuls Colletotrichum truncatum , C. gloeosporioides et Lasiodiplodia theobromae ont caus\ue9 la br\ufblure foliaire du melon Egusi