We tend to think of viruses as nasty germs that we try desperately to get rid of, whether they’re in our bodies, or in our gardens.

However, only a small percentage of the many viruses are pathogens, said Marilyn Roossinck, professor of plant pathology and environmental microbiology, and biology. Roossinck recently gave a talk about plant viruses at the Millennium Café, a weekly coffee break and science chat at Penn State’s Millennium Science Complex.
In fact, most viruses can work with a plant, as well as fungi, to improve plant health. They can boost heat and drought tolerance of certain plants, for example. Viruses can give plants beauty makeovers, too, that — by the way — can lead to economic bubbles. It was this type of viral artistry that helped create Tulip Mania in Holland during the 1630s.