09/29/06 Fighting Canada thistle

Canada thistle has a bad reputation and rightly so. This noxious weed, one of dozens of weed species that have invaded Idaho, can be found in pastures and fields, on ditches, next to the road, just about anywhere. There are chemical controls. Some people burn the plant, others hand pull it. But now researchers at the USDA lab in suburban Washington DC may have stumbled onto a biological control agent. Entomologist Ron Ochoa says a colleague noticed that some of the thistle was dying and he couldn't figure out why. OCHOA "After he took some of the leaf and put it under the microscope that he saw some tiny little white things moving around." What were moving around were mites but how do you get them from the laboratory onto the thousands of acres invaded by Canada thistle? OCHOA "And we are looking everywhere to find a virus that can be carried with this mite because the mite is host specific. Usually the wind will spread and go over the Canada thistle and only feeds and likes to eat Canada thistle." Purple loosestrife grows along mile after mile of Idaho waterways. An insect that feeds only on loosestrife has been used to clear away that invasive weed. Insect populations die off as the plants succumb and die. Voice of Idaho Agriculture Bill Scott