Bidens mottle virus, an emerging pest of sunflower in South Africa
In South Africa, during a study on optimal planting date for sunflower (Helianthus annuus) conducted in the 2020/2021 and 2021/2022 growing seasons in Gauteng Province and North West Province unusual leaf and floral symptoms typical of viral infection were observed. Symptoms included leaf chlorosis, curl, mottle, rugosity, plant stunting, flower abortion, and significantly reduced yield. RNA sequencing and RT-PCR determined the presence of bidens mottle virus (Potyvirus bidenstessellati, BiMoV) in symptomatic plants. This is the first record of BiMoV in South Africa and the second report of natural infection of BiMoV in H. annuus. BiMoV has a wide host range and Mapfumo et al. (2025) suggest that weeds near fields, including blackjack (Bidens pilosa) could be reservoirs for crop infection.
BiMoV has previously only been reported in the USA, Taiwan and Brazil. It has a wide host range, affecting many members of the Asteraceae, Brassicaceae and Fabaceae families. BiMoV is a widespread potyvirus that is vectored by aphids.BiMoV has been reported to cause significant losses for some ornamental and horticultural crops including lettuce (Lactuca sativa) and endive (Cichorium endivia).
Sources
Mapfumo P, Archer E, Swanevelder DZ, Wilken M, Creux NM, Read D (2025) Genomic characterisation of Bidens mottle virus in South Africa and an assessment of the impact on Helianthus annuus (sunflower) in an open field setting. Plant Pathology 74(5), 1266-1276 https://doi.org/10.1111/ppa.14089