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...

Recently I was a participant on an educational noxious weed tour in Sierra Valley. It is a beautiful mountain valley where most agricultural production is devoted to grazing and hay production. The tour was set up by the Plumas Weeds group, to show land managers and ranchers various noxious weeds which are invading Sierra Valley. We discussed identification, biology, and control options for a variety of weed species. One of the questions which was inevitably brought up for each species was: “How long is the soil seed life of this weed?” This question led to interesting conversations.

When we stopped to look at hoary cress (Lepidium Draba) we had a relatively optimistic conversation. Hoary cress is a B list...

Here are a few articles from California Ag Today

Mechanical Weeding Saves Labor
http://californiaagtoday.com/mechanical-weeding-vegetables/

Tracking Herbicide Resistance in Weed Evolution 
http://californiaagtoday.com/herbicide-resistance-weed-evolution/

The Economist reports that Hungarian biologists have trained rabbits to preferentially eat common milkweed (Asclepias syriaca), an invasive plant (and a native to North America).

http://www.economist.com/news/science-and-technology/21705297-milkweed-toxic-and-hard-get-rid-answer-train-rabbits-it-now