The plant Tansy Ragwort is making a comeback in Oregon because of the La Nina weather pattern. The plant is fatal to cattle that eat it. Entomologist Eric Coombs says they battle it naturally, with insects such as the flea beetle and cinnabar moth, but it takes time. Tansy Ragwort is part of the sunflower family and was introduced in Oregon in the 1920's. Within three decades it became a major problem, killing thousands of cattle and horses.