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(1) "Block" means a contiguous grouping of registered plants separated by at least 10 feet from other contiguous groupings of registered plants. Exemptions for closer spacing of registered plants may be granted by the department when risks of infection from targeted pests is low and plant spacing is consistent with current industry standards.
(2) "Clean cultivation" means the site is bare earth or is planted with a grass (Gramineae) or another crop approved in writing by the department in which broad-leaved weeds are actively controlled.
(3) "Department" means the Washington state department of agriculture.
(4) "Diagnostic assays" means those tests used to detect viruses and virus-like pathogens and may include use of herbaceous or woody indicator plants, serological tests, polymerase chain reaction assays, high throughput sequencing, canine detection, and/or other scientifically validated means.
(5) "G1" refers to the original plants (nuclear materials) plant line, variety, or cultivar that has been:
(a) Tested for, and found free of, economically important and/or harmful plant viruses and virus-like organisms; and
(b) Been maintained under controlled conditions to prevent reinfection.
Production and maintenance of G1 material must be in within the NCPN-FT system or equivalent program as approved by the department director.
(6) "G2" means plant material that is propagated from G1 stock and maintained by the certified nursery under the specific conditions outlined in this chapter to prevent (re)infection.
(7) "G3" means plant material that is propagated from G1 or G2 stock to increase the amount of source material available for producing virus-tested certified nursery stock. G3 plants must be maintained under the specific conditions outlined in this chapter to prevent (re)infection.
(8) "G4" means plant material that is propagated from G1, G2, or G3 stock that will be commercially distributed.
(9) "Index" means to determine virus infection by means of inoculation from the plant to be tested to an indicator plant or by any other scientifically acceptable means of detection.
(10) "Indicator plant" means any herbaceous or woody plant used to index or determine virus infection.
(11) "NCPN-FT" means the United States Department of Agriculture National Clean Plant Network for Fruit Trees.
(12) "Off-type" means different from the cultivar as stated on the application for certification.
(13) "Registered tree" means a tree or clonal planting that has a registration number assigned to it by the department, and that has been inspected and tested in accordance with the provisions of this chapter.
(14) "Scion block" means a planting of registered G2 or G3 trees, which serves as a source of scionwood for the propagation of Washington certified nursery stock.
(15) "Seed block" means a planting of registered G2 or G3 seed trees, which serves as a source of seed for producing rootstock used in the propagation of Washington certified nursery stock.
(16) "Stool bed" means a clonal planting of self-rooted registered G2 or G3 trees for the specific purpose of producing vegetatively propagated rootstock used in the propagation of Washington certified nursery stock.
(17) "Targeted" refers to harmful viruses and virus-like agents that cause diseases of commercial pome and stone fruit trees (plant genera Amelanchier, Chaenomeles, Cydonia, Crataegus, Malus, Prunus, Pyrus, and Sorbus) and that may be tested for as a condition of participation in the certification program.
(18) "Tested" means having been subjected to an official examination, other than visual, to determine if pests are present or to identify pests.
(19) "Tissue culture" means a general term for the cultivation of plants (cells, tissues, or organs) under aseptic conditions in a synthetic medium in vitro. It also refers to the cultures themselves.
(20) "Topworking" means the propagation by budding or grafting of scionwood onto a rootstock or established tree.
(21) "Virus" means virus and other graft-transmissible virus-like entities such as phytoplasma and viroids.
(22) "Virus infected" means the presence of a targeted virus in a plant or plant part.
(23) "Washington certified nursery stock" means G4 plant materials including nursery-grown seedlings, clonal root-stocks originating from registered G2 or G3 trees, nursery-grown trees propagated by using top-stock from registered G2 or G3 trees, and rootstock originating from registered G2 or G3 trees of the plant genera Amelanchier, Chaenomeles, Cydonia, Crataegus, Malus, Prunus, Pyrus, and Sorbus.
(24) "Washington certified seed" means seed produced on registered G1, G2, or G3 seed trees. It could also pertain to virus-tested seed from other sources approved by the department for production of G4 trees.
[Statutory Authority: RCW 15.14.015. WSR 26-10-008, s 16-350-015, filed 4/27/26, effective 5/28/26. Statutory Authority: Chapter 15.14 RCW. WSR 00-19-036, § 16-350-015, filed 9/12/00, effective 10/13/00; WSR 90-23-006 (Order 2058), § 16-350-015, filed 11/9/90, effective 12/10/90; Order 1331, § 16-350-015, filed 1/15/74; Order 1300, § 16-350-015, filed 3/26/73; Order 951, Regulation 1, filed 7/2/64; Order 890, Regulation 1, effective 9/17/62.]