Bear Valley Community Services District

Help Control the Spread of Yellow Starthistle

Yellow Starthistle poses a threat to land values and livestock

Published on:
February 24, 2020
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ellow Starthistle is considered one of the most serious rangeland weeds in the western U.S. It is a noxious, invasive plant that reduces the value of land by forming dense, impenetrable stands that interfere with land use, choke out native vegetation, reduce habitat for our wild neighbors, and are toxic to horses. A single plant can produce over 100,000 seeds, 95% of which are viable soon after dispersal. These seeds can live in the soil for up to 3 years.

Dense, impenetrable stands of Yellow Starthistle reduce land value by choking out native vegetation, ruining habitat for wildlife, and poses a deadly risk for livestock.

Dense stands have formed at lower elevations in the valley on public and private property alike, and it is quickly spreading. These stands can double exponentially each year when left undisturbed, and they are already choking out areas of Sycamore Canyon and the meadow.

Bear Valley CSD is Taking the Intiative

A team has been formed including interested residents, BVCSD personnel and BVSA staff to tackle this issue in our valley.

BVCSD personnel will soon begin spraying roadsides and drainage easements with an herbicide called Transline (clopyralid) to help control the spread of Yellow Starthistle throughout the valley. This herbicide was chosen because it has both pre-emergent and post-emergent effects on Yellow Starthistle and is considered safe enough to use on food crops and pastures.

Landowner Responsibilities

Eradication of this weed requires community-wide compliance. The tiny seeds are carried all over the valley when they attach to wild animals, livestock, shoes and even stroller wheels.

The District has a weed abatement policy in its code that states: “It shall be the duty of every owner of property located in the district to remove or destroy…weed and debris accumulating on the owner’s property. It shall be unlawful for an owner of property located within the district to cause or permit such accumulations of weeds or debris to remain on the property”.

Lifecycle and Management

The rosette stage of Yellow Starthistle looks very similar to a dandelion

December - March: Seeds are germinating below ground during the rainy season.

March - June: Seedlings emerge and the plant lives in the rosette stage, sending a tap root 6+ feet into the ground to sustain itself during the dry season.

June - December: Flowering continues throughout summer and fall.

The plants may bolt sooner in the year depending on temperature and rainfall.

Abatement Methods

Mechanical Control (pulling, cutting, disking)

Hand removal, when used to prevent seed production for 3 or more years, can significantly reduce or eliminate an infestation. Seeds can lie dormant in the ground for 2-3 years, so this method must be continued each spring until all seeds have germinated and plants have been eliminated.

To ensure that the plants do not recover, it is important to remove all above-ground stem material. The best time for manual removal is after the plants have bolted, but before they produce viable seed (early flowering stage). These plants should be taken to the Transfer Station and placed in the burn pit provided for Yellow Starthistle.

Chemical Control
UC Davis study of Milestone effectiveness on yellow starthistle

Where large stands exist on uneven ground, chemical control is often the only viable method. Attached to this article are some informative documents about herbicides used for Yellow Starthistle. They give a breakdown of each chemical, application specs and the life-stages of effectiveness.

We are each responsible for our properties, but this noxious plant has an effect on the entire community – reducing property values, limiting access to public areas, and posing a threat to our livestock. If you have any questions or need advice on treating your property, please contact the Bear Valley Community Services District at 661-821-4428 or Laurie Rude Betts at 661-821-1904.