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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #352067
Title: HLB-related responses of Valencia on eight diverse rootstocks in greenhouse trials

Author
item Stover, Eddie
item Hall, David
item GROSSER, J - University Of Florida
item GRUBER, B - University Of Florida
item MOORE, G - University Of Florida

Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2018
Publication Date: 6/25/2018
Citation: Stover, E.W., Hall, D.G., Grosser, J., Gruber, B., Moore, G. 2018. HLB-related responses of Valencia on eight diverse rootstocks in greenhouse trials[abstract], Florida State Horticultural Society Meeting, June 10-12, 2018, Ft. Lauderdale, Florida.

Interpretive Summary:

Technical Abstract: The primary purpose of this experiment was to see if selection of rootstock affects the development of huanglongbing (HLB)-related decline. ‘Valencia’ was budded February 2013 onto 40+ rootstocks each of Carrizo, Cleopatra, Green-7 from UF, Orange-4 from University of Florida, Orange-19 from University of Florida, Rough Lemon, Sour Orange and US-897. In Sept. 2013 twenty+ ‘Valencia’ trees on each rootstock trees were graft inoculated with Candidatus Liberibacter asiaticus (CLas). In a separate experiment similar numbers of trees were CLas+ Asian citrus psyllid (ACP)-inoculated in no-choice inoculations. Trees were maintained in an ACP-free greenhouse using fertilization and irrigation typical for nursery production. Data were collected periodically on trunk diameter and tree height, with tree health assessed on a five point subjective scale. Leaf and root samples were collected annually for quantification of CLas using quantitative polymerase chain reaction (qPCR). For the bud-inoculated trees: only Rough Lemon and Sour Orange consistently displayed diameters greater than Carrizo (and Green-7); after three years, trees on Orange-19 displayed greater overall health than trees on Carrizo (and Green-7, Sour Orange and US-897); trees on Orange-19 displayed a higher percentage of plants with leaf Ct for CLas greater than 36 compared to trees on Carrizo (82% and 50% respectively). For the ACP-inoculated trees: only Rough Lemon, Sour Orange, and US-897 consistently displayed diameters greater than Carrizo (and Green-7, and Orange-4); after three years, trees on Orange-19 displayed greater overall health than trees on other rootstocks except Orange-4 and and Sour Orange; trees on Orange-4 and Carrizo displayed a higher percentage of plants with leaf Ct for CLas greater than 36 compared to trees on all other rootstocks except Green-7 and Orange-19. In both experiments, there was no difference between rootstocks on growth rate and Valencia on Orange-19 showed a statistically significantly better health score than trees on most other rootstocks by Dec 2016. With assessment of CLas titer at only one year (leaf Dec 2014 and roots Dec 2015), there is no evidence that trees on any other rootstock suppresses titers compared to Carrizo. Less than 9% of plants showed CLas Ct <36.