Assessment of Field-Grown Cucurbit Crops and Weeds within Farms in South-West Nigeria for Viral Diseases

Abstract


 Cucurbits are economic crops in Nigeria which serve as additional nutritional supplements and also good sources of income for farmers. Viral diseases are a worldwide problem of cucurbits and a major limiting factor for cucurbit production. A survey of farmer’s fields where cucurbit crops were grown was carried out to assess the incidence and severity of virus symptoms and viruses associated with the crops and weeds in selected locations in Ogun and Osun, in southwest Nigeria, in June, 2012. In all, 38 leaf samples were collected in Ogun state and 52 in Osun state from cucurbit crops and weeds. Leaf samples were tested against Cucumber mosaic virus (CMV), Melon necrotic spot virus (MNSV), Papaya ringspot virus (PRSV), Watermelon mosaic virus (WMV),Zucchini yellow mosaic virus (ZYMV) and Cucumber green mottle mosaic virus (CGMMV) using Double Antibody Sandwich (DAS) enzyme-linked immunosorbent assay (ELISA). All the fields surveyed had virus symptom incidences of 100% except for melon fields in Osun state with incidences of between 10 and 30%. In Ogun state, the occurrence of CMV was 5/31 (16.1%) while MNSV was detected in Lagenaria siceraria and T. occidentalis and it occurred in 6.5% of the leaf samples. In Osun state, CMV was detected in watermelon, melon and weeds found in all locations surveyed. The occurrence of CMV was 9/38 (23.7%) in the cucurbit crops and in 78.6% (11/14) of the weeds. PRSV and WMV also occurred in mixed infection with CMV in 7.1% respectively. CMV was the most widespread and prevalent virus infecting cucurbit crops and weeds.Cucurbits are economic crops in Nigeria which serve as additional nutritional supplements and also good sources of income for farmers. Viral diseases are a worldwide problem of cucurbits and a major limiting factor for cucurbit production. A survey of farmer’s fields where cucurbit crops were grown was carried out to assess the incidence and severity of virus symptoms and viruses associated with the crops and weeds in selected locations in Ogun and Osun, in southwest Nigeria, in June, 2012. In all, 38 leaf samples were collected in Ogun state and 52 in Osun state from cucurbit crops and weeds. Leaf samples were tested against Cucumber mosaic virus (CMV), Melon necrotic spot virus (MNSV), Papaya ringspot virus (PRSV), Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV) and Cucumber green mottle mosaic virus (CGMMV) using Double Antibody Sandwich (DAS) enzyme-linked immunosorbent assay (ELISA). All the fields surveyed had virus symptom incidences of 100% except for melon fields in Osun state with incidences of between 10 and 30%. In Ogun state, the occurrence of CMV was 5/31 (16.1%) while MNSV was detected in Lagenaria siceraria and T. occidentalis and it occurred in 6.5% of the leaf samples. In Osun state, CMV was detected in watermelon, melon and weeds found in all locations surveyed. The occurrence of CMV was 9/38 (23.7%) in the cucurbit crops and in 78.6% (11/14) of the weeds. PRSV and WMV also occurred in mixed infection with CMV in 7.1% respectively. CMV was the most widespread and prevalent virus infecting cucurbit crops and weeds.

Biological, Serological and Molecular Characterization of Cucumber mosaic virus (CMV) Infecting Cucurbita moschata (Duchene ex. Poir) (Summer Squash) in Itu and Uyo Local Governments Areas, Akwa Ibom State, Nigeria

“…If the virus could infect other cucurbits beside the one studied, this is a pointer to how economically important the virus could be. With regards to insect transmission, all the isolates were transmitted mechanically by A. spiraecola in fore-gut manner corroborating previous report on transmission of the CMV by the aphid species [22,23]. The ubiquity of the A. spiraecola and the ability of the aphid to transmit the virus isolates could have been responsible for their widespread in Akwa Ibom.…”

“…Cuccumber mosaic virus (CMV) is reported to have a host range of more than 1,200 species in 521 genera from 100 families [31]. Previous reports by Arogundade et al [24] and Ayo-John et al [22,23] on the same virus also confirm this. If the virus could infect other cucurbits beside the one studied, this is a pointer to how economically important the virus could be.…”

“…Eyong et al [20] have also reported what they considered a new species of virus called Telfairia severe mosaic virus from Telfairia occidental is in Calabar with a sequence identity of 75% with Moroccan watermelon mosaic virus (MWMV). Cucumber green mottle virus (CGMMV), Melon necrotic spotvirus (MNSV), PRSV and CMV have also been reported infecting cucumber, watermelon, Lagenaria siceraria and T. occidentalis in Ogun and Oyo States and derived savannah agro-ecology in Nigeria [21][22][23][24].…”

Rapid defense mechanism suppression during viral- oomycete disease complex formation

“…CGMMV is easily spread by mechanical contact, and seeds (Reingold et al, 2016). Observations in commercial trellised cucumber greenhouses that documented CGMMV spread revealed extensive collapse and growth inhibition of plants 3 to 6 weeks post-planting (Antignus et al, 2001;Ayo-John et al, 2014) due to combined infection of CGMMV with the soilborne pathogen Pythium spinosum (Philosoph et al, 2018). This oomycete pathogen infects several hosts, including cucumbers (Al-Sa'di et al, 2007;Toporek and Keinath, 2020) resulting in damping-off and root rot in very young seedlings, but rarely causes apparent damage in mature plants (Hendricks and Roberts, 2015;Sigillo et al, 2020).…”