In Cameroon, oil palm ( Elaeis guineensis Jacq.) is of economic importance. However, it is affected by vascular wilt presumed to be caused by Fusarium oxysporum f. sp. elaeidis (FOE). Accurate species identification requires molecular-based comparisons. The aim of this work was to molecularly identify Fusarium species associated with diseased oil palms and to determine the pathogenicity of selected isolates. Fungal samples of diseased palms were collected from the canopies and the soil of five oil palm estates of the Cameroon Development Corporation and characterized by sequencing and comparing the translation elongation factor 1a gene. The results revealed the presence of FOE from approximately 80% of the isolates. Cameroonian isolate within FOE clade 1 exhibited the greatest variability grouping with isolates from Suriname, Brazil and Democratic Republic of Congo. Other isolates found in FOE clade 2 formed a unique group which was comprised solely of isolates originating from Cameroon. Twenty-two isolates were chosen for pathogenicity tests. After a short time, 14 isolates were found to be pathogenic to oil palm seedlings. This study revealed the pathogenicity of FOE isolates from Cameroon and demonstrated that FOE in Africa is more diverse than previously reported, including a lineage not previously observed outside of Cameroon. Comparisons between all isolates will ultimately aid to devise appropriate control mechanisms and better pathogen detection methods.

Spectroscopy has become one of the most used non-invasive methods to detect plant diseases before symptoms are visible. In this study it was possible to characterize the spectral variation in leaves of Solanum lycopersicum L. infected with Fusarium oxysporum during the incubation period. It was also possible to identify the relevant specific wavelengths in the range of 380–1000 nm that can be used as spectral signatures for the detection and discrimination of vascular wilt in S. lycopersicum. It was observed that inoculated tomato plants increased their reflectance in the visible range (Vis) and decreased slowly in the near infrared range (NIR) measured during incubation, showing marked differences with plants subjected to water stress in the Vis/NIR. Additionally, three ranges were found in the spectrum related to infection by F. oxysporum (510–520 nm, 650–670 nm, 700–750 nm). Linear discriminant models on spectral reflectance data were able to differentiate between tomato varieties inoculated with F. oxysporum from healthy ones with accuracies higher than 70% 9 days after inoculation. The results showed the potential of reflectance spectroscopy to discriminate plants inoculated with F. oxysporum from healthy ones as well as those subjected to water stress in the incubation period of the disease.