(a) The trees in a foundation block shall be established using:
  (1) Certified budwood or budwood from a certified source tree that has been tested by a certified laboratory no more than 90 days prior to the date budwood is cut and found to be free of tristeza virus, citrus greening disease, exocortis viroid, cachexia viroid, psorosis virus, citrus tatterleaf virus, concave gum, and any other pests of regulatory concern; or
  (2) Budwood imported directly from the California Citrus Clonal Protection Program, the Bureau of Citrus Budwood Registration of the Florida Department of Agriculture and Consumer Services or the USDA-ARS National Clonal Germplasm Repository for Citrus, when accompanied by documentation certifying that the budwood is free of the diseases listed in paragraph (1) of this subsection.
(b) Budwood used to establish a foundation block shall originate from trees that exhibit desirable horticultural true-to-type characteristics for the specified varieties:
  (1) in accordance with the Citrus Industry Volume I, edited by Reuther, Webber and Batchelor, published by the University of California Division of Agricultural Sciences in 1967;
  (2) that were developed since publication of The Citrus Industry in accordance with other recognized scientific reviewed publications containing variety release articles; or
  (3) as determined by review of specific variety information by the director of the Texas A&M University-Kingsville Citrus Center.
(c) Each tree planted in a foundation block, shall be assigned a unique source tree identification number consisting of block abbreviation, variety abbreviation, block number, row number, and tree number. A sign, stake, tag or other permanent and waterproof marker shall be used to associate each tree with its unique number.
(d) Foundation block trees shall be examined during first fruiting and annually thereafter by a panel of experts designated by the department to verify horticultural characteristics. Any tree not exhibiting desirable horticultural characteristics for the specified variety shall be immediately removed from use as a budwood source.

Source Note: The provisions of this §21.31 adopted to be effective December 31, 2015, 40 TexReg 9626; amended to be effective March 22, 2018, 43 TexReg 1629