Project Number: 2036-21000-010-14
Start Date: Oct 01, 2011
End Date: Sep 30, 2014
While the evaluation of the block for huanglongbing (HLB) will continue for another year, the preliminary findings suggest that P. trifoliata and its hybrids are largely still negative based on testing results for three years. Additionally, most of the sour orange type and kumquat genotypes have tested negative for HLB. We have received an evaluation grant from the USDA ARS National Germplasm Programs to fund for testing the block for HLB in Oct 2011, so additional information will be obtained. Similar observations were made from testing plants in the arboretum in Winter Haven, although the challenge pressure is not as severe in Central Florida as it is in the Ft. Pierce area. Barkley, et al (2006) summarized her research on the genetic diversity and population structure of 370 citrus hybrids maintained at the citrus variety collection, UCR, which she analyzed using SSR markers. Using her data, we have a total of 80 genotypes in the citrus variety collection which have either sour orange, P. trifoliata, or kumquat as part of their population structure. In addition from holdings at the Repository and in the citrus variety collection, we have selected 8 kumquat accessions, 17 sour orange types, and 40 P. trifoliata and P. trifoliata hybrids not included in the 80 genotypes identified from Barkley’s work mentioned earlier. From the targeted list of about 145 genotypes with potential tolerance to HLB, only five have been tested in the first germplasm screening experiment. Seed will be collected, sent to Florida where seedlings will be grown out, half of the seedlings to be planted will be inoculated with HLB before planting so differentiation may be made between free choice by the psyllid and inherent genetic tolerance to HLB from the plant. Replicated, randomized, single tree plots will be planted in the field, and evaluations made twice a year for growth, colonization by psyllids, incidence of citrus canker, and samples collected for testing for presence of Candidatus Liberibacter asiaticus.