Reporter Carol Brodsky of the Ukiah Daily Journal suggests most readers are familiar with yellow starthistle, a noxious weed thought to have been introduced from Chile more than 100 years ago. Though yellow starthistle is controlled by a variety of insects and competitive weeds in its natural habitat, in California people are its primary enemy.
And yellow starthistle is a formidable foe. It can grow six feet tall and as much around. The flowers are beautiful, but surrounded by sharp, one-inch-long spikes.
John Harper, the UC Cooperative Extension livestock and natural resources advisor in Mendocino County, told the reporter that the plant has features that make it especially hard to eradicate.
"Starthistle has two seeds. One is hard coated and the other is soft coated. The soft coated seeds sprout instantly, and the hard coated seeds wait for the late-season rains," Harper was quoted.
The plant contains a neurotoxin which can be deadly to horses. Fortunately, most horses find starthistle unpalatable. However, other animals are unaffected. Harper suggests the best method to eradicate the weed is running sheep and goats on the property.
There is a silver lining to the weed's introduction to California: Yellow starthistle is considered an important source of the state's honey.