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Photo elnudomolesto
Downy mildew, which has all but wiped out impatiens as a bedding plant in the USA and several other countries, is now spreading to other ornamental species, such as the popular Gynura aurantiaca (purple velvet plant), as well as many basil varieties.
The findings, reported in a recent issue of the online journal Plant Disease, show that downy mildew (Plasmopara halstedii (Farl.) Berl. & De Toni) is a very aggressive fungal disease, and that it is evolving, probably in response to intensive greenhouse growing conditions in the ornamental plant industry.
Gynura aurantiaca Photo TANAKA Juuyoh (田中十洋)
Once established, downy mildew can quickly kill its host plant and its spores spread rapidly to surrounding plants. Growers will need to be vigilant in applying preventative fungicides early in the plant’s growth cycle.
The study looked at ornamental plants in a Florida nursery and found that around 30% of Gynura plants were affected. Gynura, originally from Indonesia, has beautiful soft, hairy, purple foliage and is a popular house plant and foliage plant in tropical and subtropical zones. Downy mildew will probably make it uneconomical to grow Gynura, as has happened with most impatiens varieties, other than the downy-mildew resistant New Guinea impatiens cultivars.
Citation:
First Report of Downy Mildew on Gynura aurantiaca Caused by Plasmopara halstedii sensu lato in Florida
A. J. Palmateer, Tropical Research and Education Center, University of Florida, Homestead, 33031; R. A. Cating, Hermiston Agricultural Research and Extension Center, Oregon State University, Hermiston, OR 97838; and P. Lopez, Tropical Research and Education Center, University of Florida, Homestead, 33031.
