Why some plant diseases thrive in urban environments

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Rachel Penczykowski, an assistant professor of biology in Arts & Sciences at Washington University in St. Louis, and five WashU graduate and undergraduate students tracked infestations of powdery mildew on common broadleaf weeds. Their study, published in the journal Ecology, covered 22 sites in the St. Louis area ranging from the rural environment of Shaw Nature Reserve near Gray Summit to Forest Park in the heart of the city.

Penczykowski and her team found a strong and surprising pattern: Weeds in the city had significantly more mildew than the weeds in the suburbs or countryside. “Now we need to figure out what’s driving those patterns,” she said.

While the particular fungus the team studied is harmless to other plants or animals, different species of powdery mildew can be a major threat to vegetable gardens, flowers and vineyards, said Quinn Fox, a 2023 Ph.D. graduate and the study’s lead author. “It’s a big concern in different agricultural industries,” Fox said.

At any given location, mildew did best in places where trees or buildings provided a bit of shade. This observation was backed up by experiments that made use of solar array panels at Tyson Research Center, Washington University’s environmental field station. Potted plants placed in the shade of the panels had more mildew than those exposed to full sun.

Read more at phys.org

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