Wild herbs promote wine disease
Common wild plants in California vineyards cause and promote the spread of the bacterium Xylella fastidiosa, which causes Pierce's disease on affected vines - one of the most destructive plagues in viticulture.
The pathogen is transmitted by various species of insects such as cicadas and bedbugs, but it actually comes from sunflowers, bindweed, cocklebur and other plants without causing any major damage there, as scientists led by Christina Wistrom from the University of California in Berkeley found out from field and greenhouse experiments. The animals eat and lay their eggs on these herbs that grow between the vines and especially on the edges of the crops. They pick up the bacteria and carry them to the vines.
When they also suck on the vines, they infect the xylem with the microbes: within one to three years, this leads to the water supply being cut off and the plants withering. The plague has so far been limited to North and South America, but it can also affect European varieties, so accidental introduction can also cause major damage here.
Since there is still no suitable antidote, the researchers recommend, in addition to controlling insect populations, the regular removal of wild herbs in irrigation and drainage ditches and on roadsides.