LIBRO-CONGRESO-CITRUS

S18O01
Reflections on a career in citrus rootstock evaluation and commercialization
Castle W.S.
University of Florida, Institute of Food & Agricultural Sciences (UF/IFAS), Citrus Research and Education Center, U.S.A.
bcastle@ufl.edu
The author undertook a 35-year career involved in the development and evaluation of new citrus rootstocks
and commercialization of the most promising candidates. It was apparent at the close of that journey
that rootstocks remained critical to successful citriculture, but improvements were still needed. Insights
were gained along the way about the process starting with creating new rootstocks and ending with their
adoption by growers. Many of the traditional objectives in creating new rootstocks remain in place, but new
objectives related to tree size and disease have emerged. Thus, the history of rootstock development, use
and importance in relation to other fruit crops is considered along with a particular interest of the author:
the social component of rootstock research and commercialization and its consequences regarding the time
course of evaluation and adoption of new rootstocks. Eventually, new rootstocks are released and the next
step is commercialization. Evaluation of research data and the grower selection process are the ultimate
human experience in the realm of rootstocks. Thus, because choosing rootstocks is a human endeavor, it is
influenced by many factors. Among the selection criteria is the expected use of a new rootstock. Lastly, our
reliance in Florida on cooperative research is emphasized.
S18O02
Citrus rootstocks in Morocco: Present situation and future prospects
El Guilli M. 1 , Belmahdi I. 2 and Zemzami M. 3
1 Institut National de la Recherche Agronomique (INRA), Phytopathology, Morroco; 2 Office National de la Sécurité Sanitaire des
Produits Alimentaires (ONSSA), Phytopathology, Morroco; and 3 Domaines Agricoles (DA), Virology, Morroco. mguilli@yahoo.com
Until the last decade, the Moroccan citrus industry has relied exclusively on sour orange as a rootstock.
However, rootstock trials were initiated in the 1960’s at the experimental farms of INRA. The major selection
traits targeted at that time included yield and fruit quality, compatibility with clementine varieties and
tolerance to Phytophthora Gummosis, salt and limestone soils. In spite of the outstanding results of some
rootstocks revealed by these trials, sour orange continued to be the main rootstock of choice of citrus farmers.
Not until year 2000, after a long and intense debate among citrus industry stockholders, was a real action
initiated to diversify citrus rootstocks in new plantings. While sour orange remained in use, trifoliate hybrids
(‘Carrizo’, ‘Troyer’, ‘C-35’), Citrus volkameriana, and Citrus macrophylla started to increase in percentage,
especially in large nurseries. In 2008, during a sanitary survey in the Loukous region in the North of Morocco,
CTV was detected at high incidence in many orchards. A big effort is actually being done to promote the use
of CTV tolerant rootstocks. Figures of how each of these rootstocks has developed during the last 6 years are
presented. A preliminary assessment of the impact of the rootstock shift on yield, quality and market reaction
is discussed.
S18O03
Seven hybrid citrus rootstocks released by USDA: comparison of characteristics and use
Bowman K.D. and Albrecht U.
United States Department of Agriculture, Agricultural Research Service (USDA, ARS), United States Horticultural Research Laboratory,
USA. kim.bowman@ars.usda.gov
The USDA-ARS has supported a long-term citrus rootstock breeding program in Florida, and in the past two
decades the Florida citrus industry has also provided strong financial support for USDA rootstock development.
The result of this effort has been the development and release of seven hybrid citrus rootstocks that, to
varying degrees, have achieved commercial success in Florida and in other citrus production areas around
the world. During the 2010 propagation cycle, about 62 percent of all Florida nursery trees, or 1,855,798
trees, were propagated on the seven USDA rootstocks in Florida. These rootstocks, ‘Carrizo’ citrange (Citrus
XII INTERNATIONAL CITRUS CONGRESS 2012 - 323
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