MANAGEMENT OF INVASIVE PLANTS IN THE WESTERN USA
  • Defining the Problem
    • What is a Weed? >
      • Federal Definitions of Noxious Weeds
    • Costs of invasive plants
    • Human Factor
    • Challenges of Invasive Plants
    • Wildfires in the Western USA >
      • Forest Fires: Structure
      • Bark Beetles & Forest Ecosystems
      • Rangeland Fires
    • Climate Change Impacts on Plants >
      • Climate Change: CO2, NO, UV, Ozone Impacts on Plants
      • Climate Change Impacts on Crops
      • Climate Change Impacts on C4 Plants
      • Climate Change Impacts on Rangeland
    • What are we doing?
  • Focus of this Project
    • Why Western States? >
      • Audience for these reports
    • History: Are we doomed to repeat it? >
      • Dust Bowl Re-visited >
        • China: Past & Present
        • UN Biodiversity Report
    • Policy vs. Practice
    • Ecosystems & Economics >
      • Reductionist Approach to science
      • Ecology & Feminism
      • Systems View of Life
      • Ecosystems Health
      • Economic Growth
      • Impact of the Petrochemical Industry
      • Interrelation of Economics & Ecology
    • Federal Agencies >
      • Federal Agencies and Invasive Species
      • History of Coordination with States
      • Challenges of Coordination between Federal Agencies
      • Collaboration or Confusion
    • Organizations to assist landowners
    • Federal Legislation on Invasive Species >
      • 1930s Federal Laws on Invasive Species
      • Federal Seed Act 1939
      • 1940s-1960s Federal Laws on Invasive Species
      • 1970s Federal Laws on Invasive Species
      • 1980s Federal Laws on Invasive Species
      • 1990s Federal Laws on Invasive Species
      • 2000-2010 Federal Laws on Invasive Species
      • 2011-2022 Federal Laws on Invasive Species
      • Federal Bills on Invasive Species not passed
      • Executive Orders on Invasive Species
      • Federal Excise Taxes
    • State Laws and Lists of Noxious Weeds
    • My Inspirations
  • Why we need plants
    • Native Plants
    • Plant Resources
  • Invasive Success Hypotheses
    • Unified Framework
    • Role of Diversity >
      • How Ecosystems Maintain Diversity
      • Fluctuation Dependent Mechanisms
      • Competition-based coexistence mechanisms
      • Niche Differences
      • Species Richness
    • Enemy Release Hypothesis
    • Constitutive Defense Mechanisms
    • Evolution of Increased Competitive Ability
    • Role of Microbes
    • Indirect Defense Mechanisms
    • Novel weapons hypothesis
    • Evolutionary Shifts
    • Resource Allocation
    • Evolutionary Dynamics >
      • Pre-introduction evolutionary history
      • Sampling Effect
      • Founder Effect
      • Admixture, hybridization and polyploidization
      • Rapid Evolution
      • Epigenetics
      • Second Genomes
    • Role of Hybridization
    • Role of Native Plant Neighbors
    • Species Performance
    • Role of Herbivory
    • Evolutionary Reduced Competitive Ability
    • Summary Thoughts on Research
  • Historical Record
    • Regional Conferences
    • Timeline
  • Innovative Solutions
    • Agricultural Best Practices >
      • Ecologically based Successional Management
      • Perennial Crops, Intercropping, beneficial insects
      • Soil Solarization
      • Natural Farming
      • Permaculture
      • Organic Farming
      • Embedding Natural Habitats
      • Conservation Tillage
      • Crop Rotation
      • Water Use Practices
      • Tree Planting: Pros & Cons
    • Grazing Solutions >
      • Sheep and Goat Grazing
      • Cattle & Sheep Grazing
      • Cattle and Bison Grazing
      • Grazing and Revegetation
    • Rangeland Restoration >
      • Federal Goals for Rangelands
      • Novel Ecosystems
      • Prairie Restoration >
        • Prairie Restoration Workshop
        • Weed Prevention Areas
        • California grassland restoration
        • Selah: Bamberger Ranch Preserve
      • Sagebrush Steppe Restoration >
        • Low Nitrogen in Sagebrush Steppe
      • Revegetation with Native Plants
      • Dogs as detectors of noxious weeds
    • Nudges
  • Biological Control
    • Insects as Biocontrol >
      • Impacts of Biocontrol Agents on Non-Target Species
      • Indirect Impact of Biocontrol on Native Species
    • Challenges of Using Biocontrols >
      • DNA studies on Biocontrol Insects
      • Biocontrol takes time
    • Prioritization process for Biocontrol Programs
    • Evolutionary changes impact Biocontrol
    • Vertebrates as Biocontrol Agents
  • Herbicides: History and Impacts
    • Effectiveness of Herbicides in Agricultural Lands
    • Effectiveness of Herbicides in Rangelands
    • History of Use of Herbicides and Pesticides Prior to and During WWII
    • Herbicide use during and post-World War II >
      • 2,4-D Herbicide Use
      • 2,4-D and 2,4,5-T, post-World War II
    • Modern use of Herbicides >
      • Atrazine Herbicide
      • Dicamba Herbicide
      • Glyphosate Herbicide
      • Paraquat Dichloride
      • Picolinic acid family of herbicides >
        • Picloram (Tordon 22K) Herbicide
        • Triclopyr Herbicide
    • Herbicide Resistance in Invasive Plants >
      • Herbicide Resistant Crops
      • Controlling herbicide-resistant weeds in herbicide-resistant crops
      • Best Management Practices
    • Myth of the Silver Bullet
    • Myth of Eradication
    • Merging of Agrochemical Companies
    • Impacts of Pesticides on Environment and Human Health >
      • Pesticide Drift
      • Impacts of Pesticides on Biological Diversity
      • Impacts of Herbicides on Native Plants
      • Pesticide Impacts on Insects >
        • Butterflies: The Impacts of Herbicides
        • Monarch Butterflies: Impacts of Herbicides
      • Impacts of Pesticides on Wildlife >
        • Reptiles & Amphibians: Pesticide Impacts
      • Pesticide Residue in Foods
    • Funding for Research on Pesticides
    • Commentary on Herbicide Use
  • Interviews
    • Interviews Biocontrol >
      • Biocontrol Wyoming
      • Montana Biocontrol Interview Maggio
      • Montana Biocontrol Interview Breitenfeldt
    • California Interviews >
      • Robert Price
      • Doug Johnson
    • Colorado Interviews >
      • George Beck Interview
      • Scott Nissen Interview
    • Idaho Interviews >
      • Purple Sage Organic Farms in Idaho
    • Montana Interviews >
      • Jasmine Reimer Interview Montana
      • Organic Farms Montana Interviews
    • Texas Interviews
    • Washington Interviews >
      • Ray Willard
    • Wyoming Interviews >
      • Slade Franklin Interview
      • John Samson Interview
    • Wyoming Weed and Pest Districts >
      • Josh Shorb Interview
      • Slade Franklin Interview 2
      • Lars Baker Interview
      • Steve Brill Interview
      • George Hittle Interview
      • Peter Illoway Interview
      • Robert Jenn Interview
      • Sharon Johnson Interview
      • Larry Justesen Interview
      • Gale Lamb Interview
      • Stephen McNamee Interview
      • Allen Mooney Interview
      • Rob Orchard Interview
      • Robert Parsons Interview
      • Dick Sackett Interview
      • Comments by Delena
    • NRCS Interviews: Wyoming
  • Western Weed Control Conference 1940s Minutes
    • 1942 Conference
    • 1945 Conference
    • 1946 Conference
  • Who am I?
    • My Work
    • My Adventures
    • Contact Page
  • Road Logs
    • Colorado Road Logs
    • Idaho Road Logs
    • Montana Road Logs
    • New Mexico Road Logs
    • Texas Road Logs
    • Wyoming Road Logs
  • Bibliography

Interview: Dr. Robert Price

Photo: Cheatgrass in southwest Montana.© 2020 Delena Norris-Tull
​
Interview with Dr. Robert Price, California Department of Food and Agriculture
​

Email: robert.price@cdfa.ca.gov  Work phone: 916-738-6700
 
Interview by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western

(Interview reviewed & approved Sept. 29, 2020)
 
I had a telephone interview with Dr. Robert Price in September, 2020. Dr. Price works for the Plant Pest Diagnostics Branch of the California Department of Food and Agriculture (CDFA) as a Senior Seed Botanist/Specialist. He is also the CDFA Primary State Botanist. He is a certified seed analyst and a plant taxonomist.
 
Dr. Price provided information to assist me in sorting out the various lists of noxious weeds and invasive plants in California. There is an official State list of “noxious weeds” listed in the California Code of Regulations (CCR 4500).
 
Many of the plants on that the official list have also been classified, using the State’s official Pest Risk Proposal rating system. Each species subject to analysis as a possible noxious weed species is rated based on a set of criteria given in state regulation. The species are assigned numeric risk scores of one to fifteen, which can be summarized as low (1-8), medium (9-12), or high (13-15), and a proposed letter rating of A, B, C, or D. Those ratings then go through an internal and public review process. If approved, the plants are then classified using the official letter ratings, with a rating of C implying that the species is of limited concern or very widespread and D implying that the species is considered beneficial rather than harmful. The rating system is fairly recent, and new species continue to be introduced into the state, so not all species that could be considered noxious weeds in the state have been rated and only a portion of the species that have been rated are officially listed as California noxious weeds.  The ratings assist land managers and County Agriculture Commissions in making decisions about those species that may pose a problem in their locations.
 
Noxious weed seeds are classified by regulation as either Prohibited, meaning they cannot be sold or used in the State, or as Restricted, with tolerances limits set for the amount of seed allowed in agricultural seed offered for sale in the state, following the provisions of the Federal Seed Act.  Vegetable seeds offered for sale are not currently subject to the same labeling requirements as agricultural seeds such as those from grasses, forages, and oilseeds, but vegetable seed lots of more than 1 pound in interstate commerce are now subject to noxious weed labeling in the 2020 update of the Federal Seed Act.
 
Refer to my interview with Doug Johnson for an explanation of the separate list of invasive plants developed by the California Invasive Plant Council (Cal-IPC). That list, which emphasizes invasive plant species in natural habitats, includes a number of plants not on the official State list of noxious weeds.
 
I asked Bob about the fact that some species on the California list are native plants. By current State regulations, native species can be included, but current practice is only to list native plant species as noxious under unusual circumstances.  For example, native species of dodder (Cuscuta) are included on the California noxious weed list and rated C because certain of these species are economically significant stem parasites that attack crop species and garden plants and these species can be subject to various forms of control. Native species that are not on the State noxious weed list are normally considered beneficial/native, meaning that no official control actions are applied. California regulations recommend that the designation of species as noxious weeds should not be detrimental to the agriculture of the state, as broadly defined to include forestry and horticulture, but some introduced horticultural plants can be invasive in the state and then are subject to rating and possible listing as noxious weeds.  The Cal-IPC list does also includes some horticultural and some agricultural species that have become invasive.
 
I also asked Bob which online database is best to use, for the latest information on the distribution and the most accurate authority on scientific names for plant species. The advent of inexpensive and easy to use DNA analysis in coordination with traditional taxonomic studies has resulted in significant numbers of changes to species classifications in recent years. He said that the most up-to-date database for scientific names is the USDA National Plant Germplasm System, Germplasm Resources Information Network (USDA GRIN) database.
 
The GRIN database is used by official seed analysts in the United States and Canada (and the USDA APHIS) as the official source for taxonomy and nomenclature of scientific names and their authorities (and placement in families). The database includes many agricultural and horticultural and weedy plants and some native plants from around the world. It is not an official source for common names, but does provide some common names along with synonymous scientific names, geographic distributional information at the whole state level, and literature references. 
 
A number of databases provide useful information on geographic distribution of weedy plants in North America. The USDA PLANTS database provides detailed distribution maps usually resolved to the county level, widely used common names, and photographic images, but for seed analysts it isn’t the official source of scientific names.  The distribution maps from the EDDMapS database from the University of Georgia Center for Invasive Species and Ecosystem Health are also particularly useful across the United States, and the Calflora database and Consortium of California Herbaria provide detailed distributional information for weeds and native plants within California.
 
He also said that the USDA maintains an online All-States Noxious Weed Seed List that provides information on noxious weed seed species designated in each of the States. That list is managed by the UDSA Agricultural Marketing Service in Gastonia, North Carolina. They update the scientific names in that list regularly.
 
I asked Bob, via email, about the classification of three closely related knapweed species: Are Centaurea nigra & C. nigrescens now considered subspecies of C. jacea?
 
His answer is enlightening as it helps us understand the complexities of identifying closely related invasive species that, in their new environment, have come into close contact and are now regularly hybridizing.
 
Bob wrote: “Depending on how broadly or narrowly one wants to delimit the species in this complex group, different floras have treated these Eurasian species more narrowly or more broadly.  The Flora of North America treatment (Keil and Ochsmann, 2006, 19: 181-194) recognizes C. jacea L. (brown-ray knapweed), C. nigra L. (black knapweed), and C. nigrescens Willd. (Tyrol knapweed) as separate species, as is also done by the 2nd edition of the Flora of the Pacific Northwest (Giblin et al., eds., 2018), and the earlier treatment in the Flora Europaea (Tutin et al., eds., 1976).  The treatment in the Jepson Manual of the Flora of California (Keil, 2012) treats C. nigra as a subspecies of C. jacea [C. jacea subsp. nigra (L.) Bonnier & Layens]] reflecting the observation that very variable populations in northern California [C. x moncktonii C. E. Britton, etc.] are apparently derived from hybridization between C. jacea and C. nigra. The 2012 Jepson Manual treatment indicated that as of that time C. nigrescens was not considered to be naturalized in California.
 
“So, wearing my hat as a seed analyst, I would personally follow USDA GRIN and recognize three species, but realize that a lot of plants in the field in California may not easily fit into C. nigra and C. jacea because they are apparent hybrid derivatives. The treatment used for the California noxious weed list (CCR 4500) more or less follows from the treatment in the Jepson Manual and by its synonymy indicates that all of these taxa [C. jacea L., C. nigra L., C. nigrescens Willd., and by extension any hybrids thereof] are treated as noxious weeds in California.  We may eventually update our various official lists in regulation to reflect the USDA/GRIN taxonomy, but in practice we would rate all of them as noxious weeds, particularly given that many individual plants in California will only be able to be identified as belonging to the complex species group.”

More California Interviews:
  • Doug Johnson​​
Interviews from other states
Copyright: Dr. Delena Norris-Tull, July 2020. Management of Invasive Plants in the Western USA.

These webpages are always under construction. I welcome corrections and additions to any page.
​Send me an email, and I can send you the original Word format version of any page you wish to correct.
contact Dr. Norris-Tull
Bibliography
who am i?
My work
my inspirations
my adventures
  • Defining the Problem
    • What is a Weed? >
      • Federal Definitions of Noxious Weeds
    • Costs of invasive plants
    • Human Factor
    • Challenges of Invasive Plants
    • Wildfires in the Western USA >
      • Forest Fires: Structure
      • Bark Beetles & Forest Ecosystems
      • Rangeland Fires
    • Climate Change Impacts on Plants >
      • Climate Change: CO2, NO, UV, Ozone Impacts on Plants
      • Climate Change Impacts on Crops
      • Climate Change Impacts on C4 Plants
      • Climate Change Impacts on Rangeland
    • What are we doing?
  • Focus of this Project
    • Why Western States? >
      • Audience for these reports
    • History: Are we doomed to repeat it? >
      • Dust Bowl Re-visited >
        • China: Past & Present
        • UN Biodiversity Report
    • Policy vs. Practice
    • Ecosystems & Economics >
      • Reductionist Approach to science
      • Ecology & Feminism
      • Systems View of Life
      • Ecosystems Health
      • Economic Growth
      • Impact of the Petrochemical Industry
      • Interrelation of Economics & Ecology
    • Federal Agencies >
      • Federal Agencies and Invasive Species
      • History of Coordination with States
      • Challenges of Coordination between Federal Agencies
      • Collaboration or Confusion
    • Organizations to assist landowners
    • Federal Legislation on Invasive Species >
      • 1930s Federal Laws on Invasive Species
      • Federal Seed Act 1939
      • 1940s-1960s Federal Laws on Invasive Species
      • 1970s Federal Laws on Invasive Species
      • 1980s Federal Laws on Invasive Species
      • 1990s Federal Laws on Invasive Species
      • 2000-2010 Federal Laws on Invasive Species
      • 2011-2022 Federal Laws on Invasive Species
      • Federal Bills on Invasive Species not passed
      • Executive Orders on Invasive Species
      • Federal Excise Taxes
    • State Laws and Lists of Noxious Weeds
    • My Inspirations
  • Why we need plants
    • Native Plants
    • Plant Resources
  • Invasive Success Hypotheses
    • Unified Framework
    • Role of Diversity >
      • How Ecosystems Maintain Diversity
      • Fluctuation Dependent Mechanisms
      • Competition-based coexistence mechanisms
      • Niche Differences
      • Species Richness
    • Enemy Release Hypothesis
    • Constitutive Defense Mechanisms
    • Evolution of Increased Competitive Ability
    • Role of Microbes
    • Indirect Defense Mechanisms
    • Novel weapons hypothesis
    • Evolutionary Shifts
    • Resource Allocation
    • Evolutionary Dynamics >
      • Pre-introduction evolutionary history
      • Sampling Effect
      • Founder Effect
      • Admixture, hybridization and polyploidization
      • Rapid Evolution
      • Epigenetics
      • Second Genomes
    • Role of Hybridization
    • Role of Native Plant Neighbors
    • Species Performance
    • Role of Herbivory
    • Evolutionary Reduced Competitive Ability
    • Summary Thoughts on Research
  • Historical Record
    • Regional Conferences
    • Timeline
  • Innovative Solutions
    • Agricultural Best Practices >
      • Ecologically based Successional Management
      • Perennial Crops, Intercropping, beneficial insects
      • Soil Solarization
      • Natural Farming
      • Permaculture
      • Organic Farming
      • Embedding Natural Habitats
      • Conservation Tillage
      • Crop Rotation
      • Water Use Practices
      • Tree Planting: Pros & Cons
    • Grazing Solutions >
      • Sheep and Goat Grazing
      • Cattle & Sheep Grazing
      • Cattle and Bison Grazing
      • Grazing and Revegetation
    • Rangeland Restoration >
      • Federal Goals for Rangelands
      • Novel Ecosystems
      • Prairie Restoration >
        • Prairie Restoration Workshop
        • Weed Prevention Areas
        • California grassland restoration
        • Selah: Bamberger Ranch Preserve
      • Sagebrush Steppe Restoration >
        • Low Nitrogen in Sagebrush Steppe
      • Revegetation with Native Plants
      • Dogs as detectors of noxious weeds
    • Nudges
  • Biological Control
    • Insects as Biocontrol >
      • Impacts of Biocontrol Agents on Non-Target Species
      • Indirect Impact of Biocontrol on Native Species
    • Challenges of Using Biocontrols >
      • DNA studies on Biocontrol Insects
      • Biocontrol takes time
    • Prioritization process for Biocontrol Programs
    • Evolutionary changes impact Biocontrol
    • Vertebrates as Biocontrol Agents
  • Herbicides: History and Impacts
    • Effectiveness of Herbicides in Agricultural Lands
    • Effectiveness of Herbicides in Rangelands
    • History of Use of Herbicides and Pesticides Prior to and During WWII
    • Herbicide use during and post-World War II >
      • 2,4-D Herbicide Use
      • 2,4-D and 2,4,5-T, post-World War II
    • Modern use of Herbicides >
      • Atrazine Herbicide
      • Dicamba Herbicide
      • Glyphosate Herbicide
      • Paraquat Dichloride
      • Picolinic acid family of herbicides >
        • Picloram (Tordon 22K) Herbicide
        • Triclopyr Herbicide
    • Herbicide Resistance in Invasive Plants >
      • Herbicide Resistant Crops
      • Controlling herbicide-resistant weeds in herbicide-resistant crops
      • Best Management Practices
    • Myth of the Silver Bullet
    • Myth of Eradication
    • Merging of Agrochemical Companies
    • Impacts of Pesticides on Environment and Human Health >
      • Pesticide Drift
      • Impacts of Pesticides on Biological Diversity
      • Impacts of Herbicides on Native Plants
      • Pesticide Impacts on Insects >
        • Butterflies: The Impacts of Herbicides
        • Monarch Butterflies: Impacts of Herbicides
      • Impacts of Pesticides on Wildlife >
        • Reptiles & Amphibians: Pesticide Impacts
      • Pesticide Residue in Foods
    • Funding for Research on Pesticides
    • Commentary on Herbicide Use
  • Interviews
    • Interviews Biocontrol >
      • Biocontrol Wyoming
      • Montana Biocontrol Interview Maggio
      • Montana Biocontrol Interview Breitenfeldt
    • California Interviews >
      • Robert Price
      • Doug Johnson
    • Colorado Interviews >
      • George Beck Interview
      • Scott Nissen Interview
    • Idaho Interviews >
      • Purple Sage Organic Farms in Idaho
    • Montana Interviews >
      • Jasmine Reimer Interview Montana
      • Organic Farms Montana Interviews
    • Texas Interviews
    • Washington Interviews >
      • Ray Willard
    • Wyoming Interviews >
      • Slade Franklin Interview
      • John Samson Interview
    • Wyoming Weed and Pest Districts >
      • Josh Shorb Interview
      • Slade Franklin Interview 2
      • Lars Baker Interview
      • Steve Brill Interview
      • George Hittle Interview
      • Peter Illoway Interview
      • Robert Jenn Interview
      • Sharon Johnson Interview
      • Larry Justesen Interview
      • Gale Lamb Interview
      • Stephen McNamee Interview
      • Allen Mooney Interview
      • Rob Orchard Interview
      • Robert Parsons Interview
      • Dick Sackett Interview
      • Comments by Delena
    • NRCS Interviews: Wyoming
  • Western Weed Control Conference 1940s Minutes
    • 1942 Conference
    • 1945 Conference
    • 1946 Conference
  • Who am I?
    • My Work
    • My Adventures
    • Contact Page
  • Road Logs
    • Colorado Road Logs
    • Idaho Road Logs
    • Montana Road Logs
    • New Mexico Road Logs
    • Texas Road Logs
    • Wyoming Road Logs
  • Bibliography