Biological control of perennial pepperweed in the United States
Weeds like perennial pepperweed that have creeping root systems and prolific seed production are among the most difficult to control. This Eurasian mustard plant was accidentally introduced into North America with crop seed. One reason why it has become an invasive weed could be the absence of natural enemies that attack it in its area of origin. CABI is seeking to identify specialist natural enemies from Eurasia that can be introduced into North America as biological control agents.
Biological control of oxeye daisy
Although closely related, Oxeye daisy is an invasive weed in places like North America and Australia, while Shasta daisy remains a garden favourite, especially in North America. CABI is investigating whether specialist natural enemies from oxeye daisy’s area of origin in Eurasia could be introduced in North America and Australia as biological control agents. In North America the popularity of Shasta daisy makes this a challenge because any introduced agent must damage oxeye daisy but not Shasta daisy.
Hope for biological control of houndstongue in the USA?
An invasive weed with close relatives among native species is a challenge for biological control. Houndstongue was introduced accidentally to North America from Eurasia in the mid-19th century. It has since invaded most Canadian provinces and adjacent US states. There are many native plants in the USA in the same family as houndstongue. CABI staff in Switzerland are investigating specialized natural enemies in the area of origin of the weed that could be introduced as biological control agents.
Controlling hoary cress in North America
Trade in seed brought crops to new regions, but many weeds were spread by this route too. Whitetops, also known as hoary cresses, arrived in the USA as contaminants of seed from Eurasia. They are now aggressive invaders of crops, rangeland and riverbanks. One reason for this is the absence of the natural enemies that keep them in check in their area of origin. CABI staff in Switzerland are looking into the prospects for biological control of these invasive plants.