As you drive along your hometown roads and gaze out your window, you might notice clusters of small white flowers. This persistent perennial, known as whitetop, or hoary cresses (Lepidium drabae), is not welcome in the state of Montana, and it is categorized as a noxious weed in 23 other states as well.
Brought here from Eurasia in the 19th century, whitetop continues to infiltrate crop lands, open fields, and heavily irrigated areas. It is deep rooted and aggressive, making it the perfect disaster amid your nicely designed gardens. As it increases in prevalence, we encourage you to explore an interesting method of whitetop control.
That would be the whitetop gall mite (Aceria drabae). This elusive, almost microscopic arachnid specializes in whitetop, making it a safe critter to have on your land. It survives the winter within the dormant root buds, located at the base of the whitetop stem. As spring approaches, the mites migrate out of the base and up throughout the growing plant tissue. This is where they feed and lay their eggs. Their feedings create galls, a swelling often seen along the developing stem and the flower buds. This turns the pristine white flower clusters into a green clustered mess, closely resembling broccoli. Most of the damaged flowers will not produce seeds. This also weakens the plant.
