A study was conducted in Sierra Leone to identify cassava plants that are asymptomatic and symptomatic to cassava mosaic disease (CMD) and collect planting materials for field trial establishment; determine the prevalence of CMD caused by African cassava mosaic virus (ACMV) and East African cassava mosaic virus (EACMV) using the Nuru App and virus indexing techniques; and assess selected agronomic traits in cassava. A total of 80 cassava farms spanning four provinces (Southern, Eastern, Northern, and North-West) were surveyed in April 2022. Findings showed that the cassava variants of the experiment and locations significantly (p < 0.001) affected CMD incidence, severity, growth, and fresh storage root yield traits. The CMD incidence (87.0%) and whitefly abundance (144.8) were highest, and the CMD severity was moderate (4.0) for the plants derived from cuttings obtained from symptomatic Cocoa mother plants, while plants derived from cuttings of improved mother plants exhibited no visible symptoms of the disease and the lowest population (45.1) of whiteflies. The Nuru app is inefficient for phenotypically detecting CMD at 3 months after planting (MAP), while at 6, 9 and 12 MAP, the app efficiently detected the disease using a molecular analysis technique. Resistant, non-diseased plants derived from cuttings obtained from SLICASS 4 mother plants produced the highest fresh storage root yield (54.9 t ha⁻¹). The highest storage root yield loss was recorded in the plants obtained from cuttings of symptomatic variety Cocoa mother plants harvested at Matotoka grassland ecology, Bombali District (90.2%), while those harvested from cuttings of asymptomatic variety Cocoa mother plants grown at the four test environments had a similar storage root yield loss ranging from 40.3 to 46.2%. Findings suggest the importance of genetic variability, environmental adaptation, utilization of diseased-free materials, and phytosanitation as disease management strategies for increased production. These findings provide important insights into the distribution, impact, and spread of CMD and whitefly abundance in the studied areas in Sierra Leone that could be exploited for cassava production, productivity, conservation, and population improvement.

Field and storage trials were conducted to assess the response of exotic and local yam genotypes to major diseases (anthracnose, yam mosaic virus (YMV) and dry rot) and pests (i.e., mealy bug and nematodes) for the identification of parents with desired complementary traits for crossing. The experiment was conducted at the Njala Agricultural Research Centre (NARC) experimental site in Sierra Leone during two cropping seasons, 2020 and 2021. A total of 113 genotypes of yam comprising 15 D. rotundata, 4 D. prahensilis, 7 D. esculenta, 74 D. alata, 7 D. bulbifera, and 4 D. cayenensis were assessed. Results showed a significant (p < 0.001) linear relationship between yield and disease severity among yam genotypes. In-field disease (anthracnose and yam mosaic virus) infection accounted for 38% of the total variation observed in the fresh tuber yield. Findings on fresh tuber yield revealed that for every ton increase in yield of yams, anthracnose and YMV severities at five months after planting (MAP) decreased by 0.5 and 3.1 units, respectively. About 30 genotypes had low infection of disease, of which two belonged to D. rotundata (TDr 205 and TDr 96/00587), two belonged to D. prahensilis (PSLY074-13 and BMSLY085-13), three belonged to D. bulbifera (MOSLY022-12, MOSLY024-12 and KESLY09-12), and one belonged to D. esculenta (WRSLY083-13), while the remaining were D. alata. About 27 genotypes had intermediate infection, and 14 had high disease susceptibility, all of which belonged to D. alata. Storage disease infection had a highly significant (p < 0.002) linear relationship among yam genotypes. Dry rot, mealy bug, and nematode infection accounted for 15.1% of the total variation in fresh tuber weight loss. The findings were relevant for selecting parents with complementary traits of interest targeted at yam population improvement.

A diagnostic survey was conducted in the rainy and dry seasons from 2014 to 2015 to determine the incidence and severity of major diseases of cassava in Sierra Leone. At least three chiefdoms and five villages per district were targeted. The survey was carried out in fourteen districts of the country with geo references using a GPS. On the spot assessment was conducted in all fields. Prevalence, severity and incidence were calculated. The most dominant diseases included the cassava mosaic disease and the cassava bacterial blight. The prevalence of cassava mosaic disease was high with 69.1% and 61.5% in the rainy season and dry season, respectively. The prevalence of cassava bacterial blight was 100% and 92% in the rainy season and dry season, respectively. Diseases of less importance included white spot and brown spot diseases as well as cassava anthracnose disease. The study provides bases for the deployment of improved varieties and provides information on the seasonal prevalence, incidence and severity of cassava diseases in Sierra Leone.

A dearth of knowledge exists on identifying the begomoviruses and distributing cassava mosaic viruses across key cassava-growing regions of Sierra Leone. The study aimed to identify and map the distribution of cassava mosaic disease (CMD)-associated viruses in farmers’ fields in Sierra Leone. Cassava (Manihot esculenta Crantz) leaf samples were collected in 109 smallholder farms during a geo-referenced survey conducted from 10th May to 5th June 2024. Molecular diagnostics were carried out to identify the viral strains associated with CMD. Findings revealed that infection by stem cutting was more predominant in the south, east, north, and northwest regions than in the west region. In contrast, infection by whitefly was predominant in the west, north, and northwest regions. PCR screening of 426 samples coupled with sequence analysis revealed the presence of African cassava mosaic-like (ACMV-like) viruses, and East African cassava mosaic-like (EACMV-like) viruses as single infections at 78.1% and 1.3%, respectively. Co-infections of ACMV-like and EACMV-like viruses were detected in 20.6% of the tested samples. In addition, 70.6% of the samples positive for EACMV-like virus (single and mixed infections) were found to be positive for East African cassava mosaic Cameroon virus (EACMCMV). The ACMV and co-infection of ACMV and EACMV viruses were present in all regions, while EACMCV was detected in all regions except the western area. The results indicate more prevalence of the EACMCMV variant in Sierra Leone. This study suggests utilization of participatory surveillance and good agronomic practices to manage CMD in Sierra Leone.

Tomato (Solanum lycopersicum L.) is one of the most important vegetables in the world. However, dearth of knowledge exists on cultivation technology that contributes to increased production of the crop. Meanwhile, low yielding varieties, high pests and diseases attacks, climate variability and poor soil fertility are among key production constraints that limit the increased production and productivity of tomato in Sierra Leone. A two-year field experiment was conducted at the School of Agriculture and Food Sciences experimental site during 2022 and 2023 to evaluate the effects of variety and cultivation technology (CT) on pests, diseases, growth, yield and productivity of tomato. The experiment was laid in a 2 × 4 factorial (i.e. two varieties of tomato, and four treatments: CT 1, CT 2, CT 3 and CT 4 known as control) arranged in a randomized complete block design (RCBD) with three replications. Results showed that organic (CT 1 and CT 2) and inorganic (CT 3) treatments had a positive impact on growth parameters of tomato. The CT 1 (chicken dung, mulching, and neem extract biopesticide) was most effective in promoting vegetative growth and higher fruit yield, while CT 2 (NPK 15:15:15, urea, promethrin herbicide, and chlorpyrifos pesticide) exhibited highest potency in reducing population and damage caused by diseases and pests. Findings demonstrate that improved variety and cultivation technology boost tomato tolerance to pests and diseases, as well as its growth and yield performances that could be exploited for increased production and fruit quality of the crop. The CT1 was the most effective, followed by CT 2, while CT 4 or control plots had the lowest performance. The outperformance of the organic treatments relative to the inorganic and control is suggested to be attributable to its nitrogen-rich components. Weed control was also established to be effective in both inorganic and CT 2 treatments. The findings suggest that the CT 1 should be promoted for sustainable tomato cultivation, prioritizing environmentally friendly methods for long-term success.

Dearth of knowledge exists on identification of the begomoviruses and distribution of cassava mosaic viruses across key cassava growing regions of Sierra Leone. The objective of the study was to identify and map the distribution of cassava mosaic disease (CMD)-associated viruses in farmers' fields of Sierra Leone. Cassava leaf samples were collected in 109 smallholder farms during a geo-referenced survey conducted from 10th May to 5th June, 2024. Molecular diagnostics were carried out to identify the viral strains associated with CMD. Findings revealed that infection by stem cutting was more predominant in the south, east, north and northwest regions than the west region; whereas infection by whitefly was predominant in the west, north and north-west regions. The PCR screening of 426 samples coupled with sequence analysis revealed the presence of African cassava mosaic-like (ACMV-like) viruses, and East African cassava mosaic-like (EACMV-like) viruses as single infections at 78.1% and 1.3%, respectively. Co-infections of ACMV-like and EACMV-like viruses were detected in 20.6% of the tested samples. In addition, 70.6% of the samples positive for EACMV-like virus (single and mixed infections) were found to be positive for East African cassava mosaic Cameroon virus (EACMCMV). The ACMV and co-infection of ACMV and EACMV viruses were present in all regions, while EACMCV was detected in all regions except the western area. The results indicate that EACMCMV variant occurrence may be more prevalent in Sierra Leone than previously thought. This study suggests use of good agricultural practices and participatory surveillance as a strategy for managing CMD in Sierra Leone.