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Pre-planting analyses were performed to determine soil pH, particle size, organic matter, K, Na, P and S. Eight weeks after planting, maize parts above the soil level were harvested, oven-dried and dry-matter yield were computed and recorded. Application of S fertilizer appears not to be critical to maize production in the study areas since singly added S did not produce significant increase in biomass yield. In contrast, applied P significantly increased MDY in all the soils except Obantoko II, which already contained high amount of P sufficient for maize yield. Both synergism (Alabata II and III) and antagonistic (Alabata I) interactions were observed between P and S on MDY without any interactive effect in Obantoko I soil. Application rate of 30-45 kg P ha -1 with or without 10 or 20 kg S ha -1 resulted in significant effects on the MDY in the study areas. Field studies on effects of P and S on maize grain yield are recommended.

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. “Bara” cv. was the most cultivated variety (51.6%); followed by “Bojuri” (30.4%) and “Serewe” (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±18% and 1.0±0-4.5±0.8 in Osun State to 20.0±19 - 95.0±4.5% and 2.3±1.5 - 5.0±0 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. Key words: Colletotrichum gloeosporioides, Colletotrichum truncatum, Lasiodiplodia theobromae

Cowpea is an important source of dietary proteins in the semi-arid regions of sub-Saharan Africa. Its productivity is constrained by several viral diseases and there are limited updates on the incidence and distribution of these diseases in Nigeria. This study assessed the distribution and prevalence of cowpea viruses in Southwest Nigeria. Field surveys were conducted in 2017 and 2018, in which a total of 600 leaf samples were randomly collected from 60 cowpea fields in four (Oyo, Ogun, Ondo and Osun) states at 15 fields per state and 10 samples per field. Disease incidence and severity were recorded while virus infections were confirmed by enzyme-linked immunosorbent assay or reverse transcription polymerase chain reaction. Viral disease symptoms of systemic mosaic, mottling, puckering, vein-banding, leaf deformation and stunted growth were observed. Highest virus incidence and severity (100% and 4.8 ± 0.4) were observed at Adeosun Avenue, Ondo state, whereas Boredun, Osun state had the least (80% and 3.8 ± 0.7), with some symptomless fields found among the states. Seven viruses, viz.: cowpea aphid-borne mosaic virus (CABMV), cowpea mild mottle virus (CPMMV), bean common mosaic virus-blackeye cowpea mosaic strain (BCMV-BlCM), cucumber mosaic virus (CMV), southern bean mosaic virus (SBMV), cowpea mottle virus (CMoV) and cowpea yellow mosaic virus (CYMV) were detected from 173 (28.8%) samples collected from 32 (53.3%) fields across the states. CPMMV was prevalent, detected from 30.0% of surveyed fields, whereas CYMV was the least prevalent (3.3%). Multiple infections of two to four viruses were observed among 12.5% of samples from 51.7% of fields. Highest incidence of single and multiple virus infections were observed in Ondo state. This updates on virus distributions in Southwest Nigeria will be useful for multiple virus resistance-breeding programs and other viral disease management strategies for improved cowpea productivity. Supplementary Information The online version contains supplementary material available at 10.1007/s42360-022-00576-8.

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Pests including nematodes have been reported as a limiting factor to the production of roselle worldwide.A survey of rosellefarmsinsix Northern Sates of Nigeria was conductedin 2013 to identify the diverse nematode species associated with the soils and roots of the plant and determine their population densities on farmers' fields.Eightsoil and ten plant samples were randomly collected from each of twenty farms from which nematodes were extracted and identified. Four genera of plantparasitic nematodes (Meloidogyne spp.,Helicotylenchus spp., Rotylenchulus spp.and Tylenchus spp.) were found in association with roots and rhizosphere of roselle plants. Meloidogyne were most populous (62.29%) on the roots while Tylenchuswas least (1.68%). Helicotylenchus spp appeared in highest density (50.05%) in plant rhizosphere, but not identified from the roots. The highest percentage of nematode population (22.7 %) wasfrom Katsina, followed by Sokoto (21.6%), Jigawa (17.4%), Zamfara (16.5%), Kano (15.1%) and Kaduna states (6.7%).The generally low nematode density observed might be due to low precipitation and high soil temperature of the six states.Occurrence of varied species of nematodes demands effective control measures for improved roselle productivity. Kano, Zamfara and Jigawawith low nematode population densities can be considered for further research towards the establishment of pest-free areas or area of low pest prevalence for roselle nematodes in Nigeria, useful in the agricultural export trade. Further studies are required on the determination of density economic threshold and the definitive roles of nematodes in causing low productivity of roselle.

Soyabean is an important source of protein for millions of people in developing countries. However, infection by Cucumber mosaic virus (CMV) causes devastating losses. Cultivation of resistant varieties has been identified as the best management strategy in many crops. The present study was, therefore, conducted to identify soyabean genotypes with high stability for growth and seed weight under CMV and disease-free conditions. Thus, eight soyabean genotypes were evaluated as CMV-infected and uninfected, using completely randomised design replicated five times and set up in the screenhouse at the School of Agriculture and Agricultural Technology, Federal University of Minna, (lat.9°40֬ N;long 6°30֬ E at an altitude of 220 m.a.s.l), Nigeria in 2018. Soyabean seedlings were infected with the virus by sap transmission at 10 days after sowing (DAS). Additive Main Effects and Multiplicative (AMMI) analyses of the evaluated parameters for growth and seed weight of the test genotypes showed that environments’ effects -infected and uninfected- were significant (p<0.05). They accounted for 100% Genotype × Environment (G×E) interaction. Disease-free soyabean plants enhanced significantly higher growth and seed weight than the CMV-infected plants. The AMMI and Genotype main effects (G) plus Genotype×Environment (GGE) analyses showed that TGX 1993-4FN was the genotype with the greatest stability for leaf diameter, leaf length, number of leaves per plant, number of days to flowering and seed weight. It is recommended that, the soyabean genotype TGX 1993-4FN, can be exploited for breeding purposes and strategies that will prevent CMV infection in soyabean fields should so be adopted by farmers.