Viral diseases constitute obstacles to pepper production in the world. In Nigeria, pepper plants are primarily affected by pepper veinal mottle virus (PVMV), Cucumber mosaic virus (CMV), Pepper leaf curl Virus (TLCV), Tobacco mosaic virus (TMV), Pepper mottle virus (PMV) and a host of other viruses. The experiment was carried out with a diagnostic survey on the experimental field of the National Horticultural Research Institute, Ibadan, Nigeria and on pepper farms in six local government areas within Ibadan Oyo State, Nigeria, forty samples were collected from each of the farms. Diseased samples were obtained from the field and taken to the laboratory for indexing. In ELISA test some of the samples from the pepper farms showed positive reaction to single infection with PVMV (36.79%), CMV (22.14%) while some others showed positive reaction to mixed infection of the two viruses (10%) but some also negative reaction to PVMV and CMV antisera (31.07).

Cucumber mosaic virus (CMV) occurs worldwide and is a harmful pathogen for pepper (Capsicum spp.). Transmission of the virus is normally by insect. The possibility of transmission by seed is less clear. Accessions collected from eight states in Nigeria were evaluated to determine seed transmissibility of CMV in Capsicum species. Ten percent of the accessions were seed infected with CMV. Eight plants from each of 22 accessions were artificially inoculated with sap prepared from CMV-infected pepper plants and seed from resulting fruit from the inoculated plants were extracted, planted, and the resulting seedlings tested after 8 weeks. The CMV was detected in all four accessions selected randomly from plants that fruited in which accessions NHCrB/09/059, NCr/AA/MAY/09/015, NCr/SA/01/09/050, and NCr/AA/MAY/09/051 had CMV transmission percentage of 73.33%, 66.67%, 66.67%, or 16.67%, respectively. In another experiment, 100 seed of the pepper cvs. Tatase, Rodo, and Sombo extracted from fresh fruit obtained from local markets were randomly selected and sown in a plastic tray. Germinating seed, and developing plants, were maintained in screenhouse and assayed for symptom development. Three young leaf samples were randomly selected from each stand at 7 weeks after planting and subjected to antigen-coated plate enzyme-linked immunosorbent assay (ACP-ELISA). To evaluate the detection capacity of ELISA, and to prove its reliability, a reverse transcription polymerase chain reaction assay was performed for comparison. Natural seed transmission incidence of 57%, 86%, and 71% were determined for cvs. Tatase, Rodo, and Sombo, respectively. This implies that the ability to be transmitted by seed, and the rate of seed transmission of CMV, is cultivar dependent.

Morphological and microsatellites (SSR) markers are efficient tools for determining genetic relatedness among mango cultivars. Seventeen mango cultivars were used for this study. Eight fruit quantitative traits were collected and subjected to mean separation using One-Way ANOVA and correlation using Principal Component Analysis (PCA). Also, molecular analysis was done using PCR-based SSR markers. The resulting binary matrix was analyzed using Numerical Taxonomy and Multivariate Analysis System (NTSYSpc). Significant variation (p ≤ .05) among all the 17 mango cultivars was observed for the eight quantitative traits studied. The PCA showed that the fruits length, width, thickness weights, %pulp and %stone contributed to 98.73% of the variation observed in all the mango cultivars. A total of 21 alleles were detected from the seven polymorphic primers ranging from two to five alleles per locus with an average of 3.0 alleles per locus. The polymorphic information content (PIC) ranged from 0.52 to 0.80 with an average of 0.66. Both the morphological and molecular markers showed that the mango cultivars were diverse except for ‘Saigon’ and ‘Julie’ as well as ‘Harden’ and ‘Lipen’ which though appear morphologically distinct based on the understudied traits but showed strong similarity to each other through molecular analysis. Dendrogram constructed using the Unweighted Pair Group Method with Arithmetic mean (UPGMA) based on SSR markers revealed a similarity coefficient of 48–93% indicating high level of variability and the presence of outbreeding. Results of the morphological and microsatellite (SSR) analyses showed wide diversity among the mango cultivar used in this study.

Increasing outbreaks of virus species infecting pepper (Capsicum spp.) is a major problem for growers in Africa due to a combination of factors, including expansion of pepper cultivation, abundance of insect vectors and climate change. More than 45 viruses have been identified to infect pepper crops causing economic loss in terms of reduced quality and marketable yield, sometimes up to 100%. The Pepper veinal mottle virus (PVMV), Potato virus Y (PVY) and Cucumber mosaic virus (CMV) are endemic in many countries including Uganda, Mali, Cameroon, Morocco and Nigeria. Current management options for virus infection in Capsicum spp. is by the integration of several approaches. More importantly, eradication of infected plants, cultivation of disease resistant varieties, improved cultural practices and judicious use of insecticides especially when plants are young and easily colonized by vectors. In recent years, eco-friendly control measures are needful to reduce occurrence of virus diseases in Capsicum spp.

The place of cucumber (Cucumis sativus L.) in Africa was considered insignificant for years due to its previously assumed limited uses. However, it has now gained recognition as one of the important market vegetables in the tropics because of the continued awareness of the numerous health benefits attached to its consumption. This has progressively affected its cultivation and thereby, increased outbreak of diseases and insect pests of the crop. High incidence of insect and disease infestations occur in Cucumis sativus L. due to extreme temperatures, heavy rainfall and high humid condition resulting there from, causing huge losses through reduction in yield, lowered quality of harvested produce and increased cost of production. More than 30 pests and diseases are known to contribute to the losses recorded on the crop in Africa, some of which will be discussed in this chapter.

The study was carried out to determine the comparative pathogenic response of six cultivars of soybean; TGx 1844-18E, TGx 1448-2E, TGx 1910-8F, TGx 1019-2EN, TGx 1910-8F and TGx 1876-4E to single and mixed infections with cowpea mottle virus and cucumber mosaic virus. The experiment was conducted in the screenhouse at the crop production pavilion, Faculty of Agriculture, University of Ilorin, Ilorin, Kwara state Nigeria. The results of the experiment revealed that all soybean cultivars were susceptible to single and mixed infection of the two viruses but to seemingly different extent. The single infection with cowpea mottle virus (CMeV), however, caused the most severe symptoms on the soybean cultivars. Cucumber mosaic virus (CMV) alone was not as severe as the CMeV. The mixed infection of CMeV and CMV did not cause higher severity than CMeV alone indicating that there was little or no synergistic effect between the two viruses on soybean.