Cowpea (Vigna unguiculata) is the third most important crop in Botswana. A virus survey conducted in 2022 revealed that in 47 of 51 cowpea fields visited (92.2

Coffee senna (Senna occidentalis L.) plants exhibiting mosaic, vein clearing and leaf distortion symptoms were observed in the roadsides in Palapye town, Central District of Botswana since 2022. Electron microscopic examination of a representative symptomatic sample showed the presence of flexuous filamentous particles resembling a potyvirus which could be trapped and decorated with antibodies raised against wisteria vein mosaic virus. Similar symptoms were observed in some locations in roadsides in northern towns of Letlhakane, Kavira, Kazungula and Nata in 2025. Upon mechanical inoculation of the Palapye isolate to several potential host species, only Nicotiana benthamiana, N. clevelandi and the original host (S. occidentalis) showed symptoms while the other non-legume and legume hosts did not, indicating a narrow host range of the putative virus. There was no evidence of seed transmission in S. occidentalis. High-throughput sequencing allowed the reconstruction of the almost complete genome sequence (9622 nt) of an unknown potyvirus encoding a predicted polyprotein of 3083 aa. Pairwise comparison of the polyprotein region sequences showed the highest identity ( 73

ABSTRACT The partial nucleotide sequence of the coat protein (CP) gene of Ethiopian isolates of chickpea chlorotic stunt virus (CpCSV, genus Polerovirus), beet western yellows virus (BWYV, genus Polerovirus), and soybean dwarf virus (SbDV, genus Luteovirus) was determined from lentil and chickpea plants showing yellowing, stunting, and reddening symptoms. Comparative sequence analysis of CpCSV isolates obtained from five chickpea and five lentil isolates showed 94.9%–100% and 91.9%–98.7% nucleotide sequence identity with each other and with the reference isolates, respectively. One CpCSV isolate from chickpea (MZ043728) showed a close relationship with isolates of the serotype II while the remaining nine isolates were closely related to isolates belonging to serotype I. Sequence identities of three chickpea BWYV isolates varied from 93.3% to 100% with the reference isolates, and one of them (MZ043727) displayed 100% nucleotide identity with previously reported lentil stunt virus (LStV, genus Polerovirus). The chickpea isolates MZ043725 and MZ043726 appear to be identical to each other, whereas the other isolate (MZ043727) was identical to previously identified LStV isolate. The nucleotide sequence of three Ethiopian SbDV isolates had a lower identity with GenBank isolates and their phylogenetic analysis showed that they are clustered separately from the rest of the reference isolates indicating that they are the most divergent. This result generates essential information for further research on legume viruses in Ethiopia. In addition, a detailed study should be conducted in the future to understand the prevalence of LStV and determine the potential yield losses associated with the virus in Ethiopia.

Pea seed-borne mosaic virus (PSbMV) is a significant pathogen affecting the yield and quality of lentil and chickpea crops in Ethiopia's major legume-producing regions, Amhara and Oromia. This study focuses on characterizing PSbMV and its seed transmission rates, including mixed infections under field conditions. Tissue blot immunoassay (TBIA) analysis revealed that 56.2% of tested lentil and chickpea samples were infected with PSbMV, often in mixed infections. PSbMV seed transmission rates varied widely among tested lentil genotypes, with the widely grown improved lentil cultivar Alemaya (FLIP 89-63 L) showing a transmission rate as high as 13.5%. To characterize the isolates, the partial polyprotein gene was amplified and sequenced. Analysis of these sequences showed nucleotide identities ranging from 90.5% to 100%. Phylogenetic analysis classified Ethiopian PSbMV isolates (from lentil and chickpea) into four major clades and four subclades. Five lentil isolates (EthLe204-18, EthLe547-18, EthLe12-19, EthLe84-19, and EthLe214-33-19) and one chickpea isolate (EthCp115-19) clustered in subgroup BI, while isolate EthLe343-18 clustered into subgroup BII with an American pathotype-2 isolate (AJ252242). Isolates EthLe7-21 and EthLe381-21 clustered with an Australian P-2 isolate (HQ185579) into group D. Further analysis using RDP indicates intraspecific recombination only in isolate EthLe214-19, with fragments derived from EthLe343-18 and EthLe204-18 as major and minor parents, respectively. No recombination events were detected in the other isolates. This study suggests that variations in lentil genotype resistance to seed infection could be leveraged for resistance breeding, and the impacts of mixed infections on lentil crops warrant further investigation.

Virus diseases are among the major constraints in the production of food legumes in Africa, causing substantial crop losses. Common bean mosaic and black root, cowpea mosaic, chickpea stunt, faba bean necrotic yellows and stunt, groundnut rosette, and soybean mosaic are the six diseases considered economically significant in Africa. Past research enabled the description of the main characteristics of the causal viruses, including particle and genome properties, modes of transmission, host range, and virus–vector relationships. Such information in many cases assisted in developing effective diagnostics and disease management methods such as host resistance, chemical vector control, and cultural practices. Integrating two or more of these approaches is usually more effective. The major challenge, however, remains ensuring the adoption of such recommendations at a sufficiently large scale by many farmers to have an impact over wider geographical areas. Future work should focus on scaling up the adoption of available control technologies and generating new information, including epidemiological data, to support future management decisions. Furthermore, since the occurrence and significance of viruses on food legumes in many African countries are still not studied, large-scale surveys to identify viruses, establish their distribution and impact, and working out suitable control measures are required.

A virus discovery investigation using high-throughput sequencing in sugarcane samples from Ethiopia revealed the presence of sugarcane mild mosaic virus (SCMMV, genus Ampelovirus) and sugarcane umbra-like virus (SULV, genus Umbravirus). The genome sequences of two isolates of SCMMV and one SULV were determined. The sequences of the two SCMMV isolates were 13,005 nucleotides in length and showed similar to 73.5% nucleotide identity along the genome and similar to 90.2, 96.8, and 90.4% amino acid sequence identity among each other in the RdRp, CP, and HSP70h, respectively. Isolate SCMMV ET2 showed a close relationship to group A isolates from Colombia, the USA, and the Philippines, with amino acid sequence identity of the predicted virus proteins in the range of 94-98.9%. Conversely, SCMMV ET1 shared a closer relationship with group B isolates from Colombia, Ivory Coast, and Argentina, exhibiting a 93-99% amino acid sequence identity. The complete genome sequence of SULV, comprising 3041 nucleotides, exhibited the highest identity with its counterpart from South Africa (MN868593). These findings contribute to expanding our understanding of the viral diversity within the sugarcane crop in Ethiopia.

Yam (Dioscorea spp.) is a staple food crop with cultural, nutritional and economic significance for millions of small-scale farmers in sub-Saharan Africa. While various virus-like symptoms such as mosaic and chlorosis are frequently observed in yam fields in Ethiopia, little information is available on the prevalence, distribution, and molecular characteristics of viruses causing these symptoms. The aim of this study was to investigate the incidence and distribution of yam viruses and determine the primary cause of yam mosaic diseases (YMD) in Ethiopia. Both symptomatic (n = 280) and asymptomatic (n = 110) yam leaf samples were collected and tested for potyviruses using ACP‐ELISA. In addition, the symptomatic leaf samples were screened for yam mosaic virus (YMV), yam mild mosaic virus (YMMV), and cucumber mosaic virus (CMV) by DAS-ELISA. Subsequently, total RNA was extracted from 130 leaf samples comprising 94 symptomatic and 36 asymptomatic samples representing the different study areas. The representative RT-PCR amplicons (n = 6) were Sanger sequenced. The ACP-ELISA and DAS-ELISA results showed 9.2%, and 12.9% YMV infection, respectively, while the RT-PCR analysis showed 28.5% YMV positivity rate. Both CMV and YMMV were not detected in any of the samples tested. Thus, YMV is confirmed as the primary cause of YMD in Ethiopia. YMV isolates from Ethiopia shared 92–93% nucleotide identity among themselves and 85–99% with other YMV isolates from the GenBank. Phylogenetic analysis revealed that YMV isolates from Ethiopia, South America, and west-central Africa have the most recent common ancestor, while isolates from China and Japan are clustered as sister groups. This study enhances our understanding of YMV's genetic diversity and provides valuable information regarding the first report of YMV in Ethiopia.

White yam (Dioscorea rotundata) plants collected from farmers’ fields and planted at the Areka Agricultural Research Center, Southern Ethiopia, displayed mosaic, mottling, and chlorosis symptoms. To determine the presence of viral pathogens, an investigation for virome characterization was conducted by Illumina high-throughput sequencing. The bioinformatics analysis allowed the assembly of five viral genomes, which according to the ICTV criteria were assigned to a novel potyvirus (3 genome sequences) and a novel crinivirus (2 genome sequences). The potyvirus showed 66

Maize lethal necrosis (MLN) is a viral disease caused by co-infection of Maize chlorotic mottle virus (MCMV) and a potyvirus mostly Sugarcane mosaic virus (SCMV). MLN is one of the most important maize production constraints in East Africa including Ethiopia. In this study molecular characterization was used to determine potential insect vectors that transmit MLN causing viruses in Ethiopia. Suspected insect vectors of MLN causing viruses collected from maize fields were initially identified to a genus/species level based on the morphological features. Further taxonomic determination was carried out using DNA sequencing from cytochrome oxidase primers. Pre-identified insect vectors of MLN-causing viruses were separately tested in the greenhouse for potential transmission of MCMV and SCMV. Accordingly, maize thrips, Franklinella sp. (Thysanoptera: Thripidae) and cereal leaf beetle, Oulema sp. (Coleoptera: Chrysomelidae) transmitted MCMV, whereas corn leaf aphids, Rhopalosiphum maidis Fich (Hemiptera: Aphididae) transmitted SCMV. Out of 86 maize fields surveyed, Franklinella sp. were widely distributed in 22 (25.6%) fields, mostly in Arsi and West Shewa zones of Oromia region. R. maidis was abundant in all the areas assessed, suggesting that this insect spp. is a vector for SCMV in Ethiopia. The presence of insects as vectors of MLN causing viruses on maize plants is believed to contribute to the widespread of MLN viruses from plant to plant, field to field and to new geographical areas. Thus, managing these vectors through appropriate control measures can reduce maize yield losses caused by MLN disease.

Vegetatively propagated plants like yam are prone to yield losses by viruses as infection tends to build up in successive cycles of propagation. This study aimed to eliminate yam mosaic virus (YMV) from yam using an optimized combination of thermotherapy and meristem culture. A protocol was optimized for shoot initiation, multiplication, and rooting from shoots of four yam varieties using Murashige and Skoog (MS) medium with growth regulators. A control at 26 ℃ and a thermo-treatment at 36, and 40 ℃ followed by meristem culture was used to eliminate YMV and verified using double antibody sandwich ELISA (DAS-ELISA) and reverse transcription (RT)-PCR. Results showed that the highest explant initiation rate of 87.5

Many plant virus diseases of major economic importance in sub-Saharan Africa are caused by disease complexes resulting from synergistic interaction of two or more viral agents known to enhance disease severity inflicting heavier crop losses. The most destructive of these are maize lethal necrosis disease (MLND), sweet potato virus disease (SPVD), cassava mosaic disease (CMD), cowpea mosaic disease (CPMD), groundnut rosette disease (GRD) and tobacco bushy top disease (TBTD). MLND, SPVD, CMD and CPMD are caused by synergistic interaction of two independent viruses in mixed infection, whereas GRD and TBTD represent helper-dependent synergism in which the multiple agents involved in the disease complexes which include an umbravirus, a polerovirus and a satellite RNA synergistically interact with each other for their survival and spread. Mixed virus infections can cause disease synergism due to viral suppression of RNA silencing of host defense, an increase in viral replication, enhanced viral movement or any combination of these. Each disease complex has its own characteristics, and a variety of factors affecting its epidemiology must be considered when devising diagnostic tools and management options. All the causal viruses are transmitted by insect vectors such as aphids, whiteflies, thrips, or beetles while some are transmitted by seeds or vegetative propagation. Although the diagnosis of the multiple agents is more complicated than those with single infections, multiplex methods primarily based on serology, PCR and next generation sequencing are available and widely used. This paper briefly addresses the etiology, symptoms, economic importance, synergistic mechanisms, diagnosis, field spread and management practices of these disease complexes and discusses future research needs.

Diseases caused by viruses belonging to different taxonomic groups result in substantial yield losses to chickpea and lentil production worldwide. Among the dozens of viruses infecting the two crops, phloem-restricted viruses such as bean leafroll virus, beet western yellows virus, chickpea chlorotic stunt virus, chickpea chlorotic dwarf virus, and faba bean necrotic yellows virus, which cause yellowing, stunting, and leafroll diseases, are economically the most important worldwide. Viruses such as pea seed-borne mosaic virus, alfalfa mosaic virus, cucumber mosaic virus, and pea enation mosaic virus complex, which generally cause mosaic and mottle diseases, also cause economically significant damage depending on symptom severity and incidence. Serological and PCR-based methods are available for the specific diagnosis of most of the viruses. The main approaches used to control these diseases are host resistance, chemical control of vectors, and cultural practices, preferably in an integrated manner.

A virus discovery investigation using high-throughput sequencing in sugarcane samples from Ethiopia revealed the presence of sugarcane mild mosaic virus (SCMMV, genus Ampelovirus ) and sugarcane umbra-like virus (SULV, genus Umbravirus ). The genome sequences of two isolates of SCMMV and one SULV were determined. The sequences of the two SCMMV isolates were 13,005 nucleotides in length and showed ~73.5% nucleotide identity along the genome and ~90.2, 96.8, and 90.4% amino acid sequence identity among each other in the RdRp, CP, and HSP70h, respectively. Isolate SCMMV ET2 showed a close relationship to group A isolates from Colombia, the USA, and the Philippines, with amino acid sequence identity of the predicted virus proteins in the range of 94–98.9%. Conversely, SCMMV ET1 shared a closer relationship with group B isolates from Colombia, Ivory Coast, and Argentina, exhibiting a 93–99% amino acid sequence identity. The complete genome sequence of SULV, comprising 3041 nucleotides, exhibited the highest identity with its counterpart from South Africa (MN868593). These findings contribute to expanding our understanding of the viral diversity within the sugarcane crop in Ethiopia.

Yam is a widely consumed food in the tropics and subtropics. Determination of pests (pathogens and insects) and diseases (developed pest invasions and symptoms) and the appropriate management practices are critical in existing crop production systems. This study aimed to document farmers' knowledge about yam pests and diseases and their management practices in southern Ethiopia. Data were collected from 342 systematically selected farmers and 96 yam fields in 5 major yam-growing zones (Dawuro, Gofa, Gamo, Kembata-Tembaro, and Wolaita) in southern Ethiopia using a semi-structured interview guide. The results showed that 54.1% of the farmers saved their planting materials for the next growing season, while 39.2% of the farmers purchased the planting materials from the local market every year. Most farmers (63.5%) reported that the cultivation of yam has been declining annually due to pests and diseases. White yam (Dioscorea rotundata) (Poir, Dioscoreales, Dioscoreaceae) and water yam (Dioscorea alata) are severely damaged by pests and diseases, as perceived by 33.9% and 24.9% of farmers, respectively. Farmers use healthy-looking pest- and disease-free tubers (39.5%), remove infected plants (24.0%), practice crop rotations (17.3%), and use animal manure (7.0%) to manage yam pests and diseases. Farmers' knowledge can be a starting point for seeking solutions to yam pests and disease risks. This study could play an important role in improving yam cultivation by identifying strategies to improve the recent decline in yam production to meet future food needs for a rapidly growing population.

Grass pea (Lathyrus sativus L.) is a popular legume in Ethiopia that serves as a protein source to replace chickpeas and field peas. It is a great way to address nutrition and food security in the growing population. However, one of the major issues is that it produces Oxalyl diaminopropionic acid (ODAP), which causes neurological disorders in humans and animals. The study aimed to measure the ODAP, heritability, and genetic advance of quantitative traits in northwest Ethiopian grass pea accessions. The field experiment was carried out during the 2019 rainy season, utilizing a 5x5 lattice design to assess the ODAP and non-yield quantitative traits of grass pea accessions at Ebonyi State University, Nigeria. This study showed a highly significant difference between accessions for all traits except petiole length. This finding discovered high heritability, genetic advance, genotypic and phenotypic coefficients of variation for ODAP, branch bearing length, number of secondary branches, days to flowering, plant height, and primary branch length. The average ODAP value was 0.44 percent, with values ranging from 0.17 to 0.90 percent. Only two of the 25 accessions 26627 and 238945 displayed safe ODAP values of <0.2. These findings may be important for the development of low-ODAP grass-pea cultivars.

Edible aroids are predominantly cultivated and utilized in Asia, Americas, Central and West Africa, and South Pacific Island countries. So far, 26 different virus species from 10 different families and 13 different genera have been reported infecting aroids. Of these, Dasheen mosaic virus, Taro bacilliform virus, Colocasia bobone disease–associated Cytorhabdovirus, and Calla lily chlorotic spot Orthotospovirus are among the most economically important. Alomae is a lethal disease, which can cause up to 100% production loss in taro. However, it has so far only been reported from Papua New Guinea and the Solomon Islands. Due to the vegetative propagation of aroids, managing viral diseases can be challenging. Integrated disease management efforts combining plant pathology, entomology, agronomy, plant biotechnology, and breeding should be considered to control viral diseases in aroids.

Most of the overwhelming plant diseases caused by viruses including maize lethal necrosis (MLN) are attributed to viruses transmitted by vectors. The transmission of MLN from plant to plant by vectors provides the main means of spread in the field and that cause severe economic loss. Methods to control the vectors of plant virus diseases are intended at eliminating or altering one or more of the primary contributors (vector, virus, and host plant) in the transmission process or at preventing their coming together. The current experiments were conducted to evaluate seed-treatment insecticides for their efficacy on early season control of insect vectors of MLN causing viruses. The study on the effects of insecticide treatments on germination revealed that it does not significantly influence the germination of maize seed even up to 6 months storage before planting. Among the tested seed treatment insecticides, thiamethoxam 25% at 2.0 g/kg seed and imidacloprid + thiram at rate 1.5 showed superior control efficacy against maize thrips (Frankliniella sp.) with 96.06% and 95% population reduction, respectively, and maize leaf aphid (Rhopalosiphum maidis) with 97.37% and 96.67% reduction percentage, respectively. Hence, dressing of maize seeds before planting with such insecticides can be used for early-stage protection against potential vectors of the MLN causing viruses.