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Title: Growth measurements and disease severity metrics of citrus identifies resistance and tolerance to Huanglongbing (HLB) in a Florida field planting

Author
item Miles, Godfrey
item Stover, Eddie
item Keremane, Manjunath
item RAMADUGU, CHANDRIKA - University Of California
item Lee, Richard

Submitted to: Florida State Horticultural Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2016
Publication Date: 6/13/2016
Citation: Miles, G.P., Stover, E.W., Ramadugu, C., Keremane, M.L., Lee, R.F. 2016. Growth measurements and disease severity metrics of citrus identifies resistance and tolerance to Huanglongbing (HLB) in a Florida field planting [abstract]. 129th Annual Meeting of the Florida State Horticultural Society. June 12-14, 2016, Stuart, Florida. Abstract number G11.

Interpretive Summary:

Technical Abstract: In a Ft. Pierce, Florida field planting, growth and Huanglongbing (HLB) severity were assessed as indicators of HLB-tolerance on progenies of 83 seed-source genotypes (henceforth “parent genotypes”) of citrus and citrus-relatives from the Riverside, California genebank. Trees were exposed to infected Asian citrus psyllid for six years before metrics (leaf mottle, percent canopy mottle, chlorosis, overall health, canopy density, canopy width, canopy height, trunk diameter, and number of fruit) were collected in October - November, 2015. Across all metrics, the healthiest trees with low or absent HLB symptoms were distant citrus-relatives: Balsamocitrus daweii, Bergera koenigii, Casimiroa edulis, Clausena excavata, Glycosmis pentaphylla, Murraya paniculata and one accession of Severinia buxifolia. Within citrus most of the healthiest trees with densest canopies, little leaf loss, and greater growth, were those with pedigrees that included C. medica. These included progenies of C. hybrid (‘Limon Real’), C. limetta, C. limettioides, C. limonia, C. medica, C. volkameriana, and some C. limon accessions. Trees in this category exhibited severe mottle, but maintained dense canopies and exhibited good growth. Trees from parent genotypes without citron in their background were generally the least healthy overall with less dense canopies, greater leaf loss, and little to no fruit. The exception was progenies of one Citrus aurantium accession which were markedly healthier than progenies of other non-citron-related citrus parent genotypes. Although no commercial citrus genotypes yielded progenies with strong HLB resistance, in this field experiment several progenies maintained dense canopies and good growth, and may be useful in breeding HLB tolerant cultivars.