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Encycloweedia: Weed Ratings
A noxious weed is a plant that has been defined as a pest by law or regulation. Both California and the U.S government maintain lists of plants that are considered threats to the well being of the state or the country. The two lists differ significantly.
In California, biologists of the California Department of Food and Agriculture recommend plants for listing, after consultation with outside experts and the Agricultural Commissioners of California's counties (CACs). If a plant is found to probably be "troublesome, aggressive, intrusive, detrimental, or destructive to agriculture, silviculture, or important native species, and difficult to control or eradicate", the Department will designate the plant as a noxious weed.
At the time that CDFA lists a species, it also receives a rating of A, B, C, D, or Q. These ratings reflect CDFA's view of the statewide importance of the pest, the likelihood that eradication or control efforts would be successful, and the present distribution of the pest within the state. The ratings are not laws, but are policy guidelines that indicate the most appropriate action to take against a pest under general circumstances. Local conditions may dictate more stringent actions at the discretion of the CAC, and the rating may change as circumstances change.
The precise policy language is given below. This system has been in place since at least 1977, without revision of the language. The term "commissioners" refers to the County Agricultural Commissioners.
ACTION ORIENTED RATING SYSTEM PURPOSE
To advise commissioners as to the Department's policy regarding any pest action.
DEFINITIONS
"A"
An organism of known economic importance subject to state (or commissioner when acting as a state agent) enforced action involving: eradication, quarantine, containment, rejection, or other holding action.
"B"
An organism of known economic importance subject to: eradication, containment, control or other holding action at the discretion of the individual county agricultural commissioner.
OR
An organism of known economic importance subject to state endorsed holding action and eradication only when found in a nursery.
"C"
An organism subject to no state enforced action outside of nurseries except to retard spread. At the discretion of the commissioner.
OR
An organism subject to no state enforced action except to provide for pest cleanliness in nurseries.
"Q"
An organism or disorder requiring temporary "A" action pending determination of a permanent rating. The organism is suspected to be of economic importance but its status is uncertain because of incomplete identification or inadequate information.
In the case of an established infestation, at the discretion of the Assistant Director for Plant Industry, the Department will conduct surveys and will convene the Division Pest Study Team to determine a permanent rating.
"D"
No action. (Parasites, predators, and organisms of little or no economic importance).