Many of the ranchers I've spoken with over the last year and a half have said that tumbleweed, also known as Russian thistle (Salsola sp.), is a big problem in both San Benito and Monterey counties.
Local ranchers have said that tumbleweed is

• a much bigger problem in drought years and doesn't come up as much in wet years
• eaten by cattle when it is young
• a summer annual and is likely to be more wide-spread in areas that are not grazed in summer (because cattle aren't there to control it when it starts growing more quickly)
• more widespread in steep areas or other areas that are inaccessible to cattle

Since limited research has been conducted on control methods for tumbleweed, I partnered with Elise Gornish (UCCE Restoration Ecology Specialist at UC Davis),

Richard Smith (UCCE Vegetable Crops & Weed Science Farm Advisor in Monterey County), and more recently with Josh Davy (Livestock, Range & Natural Resources Advisor in Tehama County) to look at control options on the Central Coast. So far we have installed 9 plots on 2 ranches in south San Benito County. Our three tumbleweed control treatments are herbicide (a combination of telar & 2, 4-D), seeding, and grazing. The herbicide treatment was done on 3/22 & 4/4/2016. We will seed our plots this fall with native and forage species.

We also installed a set of 3 plots to look at later-season herbicide spraying. This later herbicide treatment was done 5/27/2016, about 2 months after

spraying the first set of plots. On 8/19/2016 we went to the late-seasons spray plots to see how they were doing. Many of the tumbleweed plants were not entirely dead, but they were drying up quite a bit. What's interesting is that so far, they have not gone to seed, whereas the nearby tumbleweed plants that were not sprayed are going to seed. The vast majority of tumbleweed seeds germinate or decompose in the soil during the first year. So, effective management for 2-3 years may significantly control the population.

Reference: Orloff, S. B.; D. W. Cudney; C. L. Elmore; and J. M. DiTomaso. Pest Notes: Russian Thistle UC ANR Publication 7486. UC Statewide IPM Program, University of California, Davis, CA 95616