by Devii Rao , University of California Cooperative Extension
Yellow starthistle is an invasive rangeland weed that takes over pastures, reducing quality and quantity of livestock forage. Ranchers continue to struggle with controlling this species. Weed Control in Natural Areas in the Western United States (DiTomasso, Kyser, et al. 2013) is an excellent book with information on how to control yellow starthistle and many other invasive species that occur in California. The yellow starthistle chapter is available at:
http://wric.ucdavis.edu/information/natural%20areas/wr_C/Centaurea_solstitialis.pdf

This article summarizes the yellow starthistle chapter from this book.

Three of the main yellow starthistle control strategies are herbicide, grazing, and mowing.

Herbicides:

Seedling stageRosette stage

Several herbicides are effective on yellow starthistle, but two of the best options are Aminopyralid (Milestone) and Clopyralid (Transline). The best time to spray Aminopyralid is from the seedling stage to the rosette stage. The best time to spray Clopyralid is when the plant is in the late rosette stage. Grasses are not harmed by either herbicide.

Bolting is a stage if vigorous growth during the time of greatest list availability.Grazing: Cattle, sheep, and goats can all be used to graze yellow starthistle. The best time to graze is from the bolting stage to right before the spiny heads emerge. Bolting is the stage after the stem comes up out of the rosette, but before the flower head begins to emerge. Protein content during this stage is relatively high: 8% to 14%. Once the spines come out yellow starthistle becomes less attractive to cattle and sheep and they start avoiding it. Goats, on the other hand, are not dissuaded by the spines so they are often used in yellow starthistle targeted grazing programs. Short-duration, high-intensity grazing is the most effective grazing strategy to control yellow starthistle.

Spiny stage.Mowing: Mowing can be an effective control option if you have an area that’s flat enough for a mower to be safe and not tip over and doesn’t have too many big rocks to get in the way of the mower. It will take several years of mowing to control yellow starthistle. Control will be even better if mowing is used in conjunction with other control methods. The best time to mow is when 2%-5% of all the yellow starthistle plants are in bloom. Timing of mowing is critical. If you mow too early, yellow starthistle can grow back and produce even more seed than if you had not mowed. Mowing too early will also eliminate grasses and other existing plants that were competing with yellow starthistle. Yellow starthistle doesn’t do as well if there’s a thick mat of other vegetation to compete with. So, removing these plants releases yellow starthistle from competition, allowing it to grow better. If you mow too late, you’ll spread the seed. Researchers found that they got the best results when they mowed twice: once during the early flowering stage and then a second time 4-6 weeks later after the plants had regrown and had produced flower buds.

Blooming stagesEffectiveness of mowing also depends on how your yellow starthistle plants are growing. If you have plants that are tall, and the branches are high up on the plants, you may only have to mow once during the early flowering stage. But, if you have plants that are spread out at the base and the branches are lower on the plant, you may not be able to control it very well because the mower can’t get low enough to cut the branches.

References
DiTomaso, J.M., G.B. Kyser et al. 2013. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center, University of California. 544 pp.

Vegetation that was removed as part of a shaded fuel break project in 2017.The Resource Conservation District (RCD), working with Cal Fire and California State Parks, has scheduled Phase 3 of the Wildfire Fuel Load Reduction project along Graham Hill Road. On Monday, October 8, 2018, crews will begin the removal of invasive Acacia and French broom on approximately 1.4 acres of road front property between Rollingwoods Drive and Lockewood Lane. The work is part of a local ongoing effort to prevent wildfire and improve safety along the Graham Hill corridor. Designated as a high priority by Cal Fire, the project will help to ensure safe ingress and egress along this critical access route in the case of wildfire.

Phase 2 was completed last year when crews created a shaded fuel break involving the removal of low tree branches and dense vegetation. The selective clearing can also have a positive impact on sensitive species by improving critical habitat and reducing the risk of catastrophic fire.

The RCD and Cal Fire are working closely with the current contractor to ensure that best practices are employed to reduce the likelihood of Acacia regrowth. A plan is underway to address the resprouts that are appearing in some of the areas treated in 2016.

Funding for this project was awarded to the RCD through a grant from Cal Fire.

For more information contact Angie Gruys at the RCD at OR 831-464-2950 x22

The RCD works with local fire agencies, fire protection districts and fire safe councils to implement recommendations in the Community Wildfire Protection Plan (CWPP), print and provide a variety of brochures and resource materials and conduct a multitude of public outreach, workshops and educational efforts emphasizing fire safe awareness and prevention. For more information on how residents can prepare for wildfire visit:

Fire Safe Santa Cruz County

Do you know the water level in your private well?  Observing the level over time can provide insight into the longevity of your well and water supply. In addition to knowing your well’s condition, practicing water conservation is a cost-effective way to increase your well’s lifetime. These efforts also help ensure that we have a long-term water supply in the Mid-County Groundwater Basin. The basin provides drinking water to the residents of Capitola, Live Oak, Soquel and Aptos from the mountains to coast.

For well level tests, the well heads should have an access port of 5/8 inch (16 mm) or larger.The Resource Conservation District, in a partnership with the Santa Cruz Mid-County Groundwater Agency, is offering free water level and conservation evaluations for well owners in the Mid-county area.  You can enter your address at www.midcountygroundwater.org to determine if you are in the Mid-County Basin boundaries. Water levels are measured by using equipment that sends sound waves down the well through the access port to estimate water depth. It’s best to take the measurement twice per year – once in the spring when water levels are usually at their peak, and once in the fall when they are at their lowest. This range of water levels can be compared with measurements taken in subsequent years to establish trends. Landowners can receive no-cost water level services every year through the County of Santa Cruz.

Gerry Spinelli of the Resource Conservation District checking the flow rate of a sink.A water conservation evaluation will be completed in conjunction with the water level tests. The assessment will look at indoor fixtures to determine what upgrades, if any, will promote the greatest water use reduction. A simple outdoor irrigation audit will also be conducted with the option for more thorough evaluation for properties with large landscapes or agricultural crops. Armed with this information, landowners can take actions to improve conservation efforts and extend the useful life of their well. 

Data collected will be compiled on an anonymous basis to help the Agency better characterize water use in the Basin. The evaluations will also help drive possible services, such as rebates for low water use fixture or efficient irrigation equipment that could benefit well owners. In Santa Cruz County, rebates for low-flow toilets, washing machines, and other fixtures are currently only available to municipal water customers.

If you are interested in scheduling an appointment or want more information on this service, please contact Angie Gruys at or call (831) 464-2950 X 22.