While visiting a wine region like the Oltrepò Pavese south of Milan, you may notice that at some vineyards there are rose bushes planted in front of each row of grapevines. Why, you probably wonder?
Tradition has it that wine farmers knew from experience that roses function as an early warning alarm for diseases that affect the vines. The roses become ill just a bit earlier than the vines and so, noticing the illness in time, the farmers could treat the vines in time to avoid losses. The roses are just like the canaries that are used in mines to signal dangerous gasses. It is not quite clear whether this really worked well, although it was later confirmed that the powdery mildew (oidium) fungus that affects the roses is related to the one that attacks the vines.
Nowadays vines are resistent to many diseases and are treated in advance. The roses are there for mere historical reasons and because it’s just beautiful.