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Nigeria is the main yam-growing country of the world. In the country, various plant-parasitic nematodes have been reported constraining yam production and the storability of tubers. This study established the damage level of nematodes on white yam tubers (Dioscorea rotundata) across the major production areas in the country for management purposes. Incidence and severity of symptoms (cracking, dry rot, and galling) associated with nematodes were assessed on 1,114 yam heaps (181 vendors) from 23 markets and on 2,502 tubers from 26 farmer storage areas (yam barns) in the Humid Forest (HF), Derived Savanna (DS) and Southern Guinea Savanna (SGS) agro-ecological zones (AEZ). On yam heaps, the symptom incidence averaged 55%, 35%, and 6% for galls, dry rot, and for cracks, respectively. Only the incidence of dry rot was significantly different (P

The yam nematode, Scutellonema bradys, is a major threat to yam (Dioscorea spp.) production across yam-growing regions. In West Africa, this species cohabits with many morphologically similar congeners and, consequently, its accurate diagnosis is essential for control and for monitoring its movement. In the present study, 46 Scutellonema populations collected from yam rhizosphere and yam tubers in different agro-ecological zones in Ghana and Nigeria were characterised by their morphological features and by sequencing of the D2-D3 region of the 28S rDNA gene and the mitochondrial COI genes. Molecular phylogeny, molecular species delimitation and morphology revealed S. bradys, S. cavenessi, S. clathricaudatum and three undescribed species from yam rhizosphere. Only S. bradys was identified from yam tuber tissue, however. For barcoding and identifying Scutellonema spp., the most suitable marker used was the COI gene. Additionally, 99 new Scutellonema sequences were generated using populations obtained also from banana, carrot, maize and tomato, including the first for S. paralabiatum and S. clathricaudatum, enabling the development of a dichotomous key for identification of Scutellonema spp. The implications of these results are discussed.

A survey was conducted in north-eastern Syria to assess the distribution of the cereal cyst nematodes (CCN). The study revealed that 62% of the fields were infested with three Heterodera species: H. latipons (76%), H. avenae (31%), and H. filipjevi (9%). Molecular identification and quantification is an accurate, rapid and sensitive method. Therefore, the actin-1 gene was successfully used to develop a species-specific PCR assay to detect H. latipons; and the mitochondrial cytochrome oxidase subunit 1 (COI) gene was used to develop two species-specific PCR assays for the identification of H. avenae and H. filipjevi. Also, the COI gene was used to develop two qPCR assays for the identification and quantification of H. avenae and H. latipons. The use of resistant hosts for nematode management is considered cost-efficient and environmentally friendly. Hence, a total of 217 synthetic winter wheat lines were screened (phenotyped) for resistance to H. filipjevi in the growth chamber. The same lines were genotyped using the Amplified Fragment Length Polymorphism (AFLP) technique. Phenotyping showed that some lines are promising because of a low number of newly developed cysts; those lines are considered resistant and moderate resistant and can be used for further breeding of resistant cultivars against cereal cyst nematodes.