I'm John Roncoroni the Weed Science Farm Advisor for Napa County with responsibilty for weed issues in Marin, Sonoma, Lake and Mendocino Counties. My program's major focus is Weed Control and Vegetation Mangement in Perennial Crops. Before coming to Napa County I worked at UC Davis for over 20 years in the Weed Science program.
I am currently working on weed control issues in vineyards of the North Coast region. These include timing of herbicide applications for better weed control, and the use of herbicides that are or may become registered for organic use.
If you have a question or concern related to Weed Management or Vineyard or Orchard Floor management or need assistance in the identification of a weed species please call my office at (707) 253-4221. You can also reach me by e-mail at jaroncoroni@ucdavis.edu. Residents in the upvalley Napa area and American Canyon can call toll free at (877) 279-3065.
If you are a homeowner with weed problems please see the Master Gardener site at http://cenapa.ucdavis.edu. UCCE Napa County Master Gardeners are well trained in pest issues for small gardens. If they are unable to answer your weed related question they will bring those issues to me on a case by case basis.
The University of California Davis Weed Research and Information Center Web site is full of weed related material including a weed/herbicide susceptablity chart.