UC Riverside Journal of Citrus Pathology Title IRCHLB-IV-Abstracts of Presentations at the 4th International Research Conference on Huanglongbing Permalink https://escholarship.org/uc/item/9jw2w985 Journal Journal of Citrus Pathology, 2(1) Authors Graham, Jim Stelinski, Lukasz Publication Date 2015 DOI 10.5070/C421030222 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California 4th International Research Conference on Huanglongbing, Florida, 2015 Abstracts of Presentations ______________________________________________________________________________________________________________________________ Abstracts presented at the 4th International Research Conference on Huanglongbing in Orlando, Florida, USA, February 9–13, 2015. The abstracts are arranged alphabetically by the first author’s name. The abstracts are published as submitted. They were formatted but not edited by the Journal of Citrus Pathology. Recommended format for citing abstracts, using the first abstract below as an example, is as follows: Alabi OJ, Kunta M, Dale J, Sétamou M. 2015. Survey and detection of ‘Candidatus Liberibacter asiaticus’ in a citrus nursery facility in South Texas [abstract]. J Cit Pathol. iocv_journalcitruspathology_30222. ______________________________________________________________________________________________________________________________ Survey and detection of ‘Candidatus Liberibacter asiaticus’ in a Attraction of dispersing psyllids is the foundation for the use of colored citrus nursery facility in South Texas sticky traps surveillance by sticky traps. Conversely, the use of UV- OJ ALABI1, M Kunta2, J Dale3, and M Sétamou2 reflecting mulch provides protection of young trees from infestation. 1Department of Plant Pathology and Microbiology, Texas A&M Detailed knowledge of the visual system of these insects can provide the AgriLife Research and Extension Center, Weslaco, 78596 TX; 2Texas basis for enhanced sensitivity by surveillance traps and a better A&M University, Kingsville Citrus Center, Weslaco, 78599 TX; 3Texas understanding of the potential for visual cues as repellents. Using Citrus Mutual, 901 Business Park Dr #400, Mission, 78572 TX. electroretinograms, the spectral sensitivities of male and female citrus Huanglongbing (HLB) disease, associated with ‘Candidatus Liberibacter psyllids were determined. Regions of maximal sensitivity were matched asiaticus’ (CLas), is primarily spread via infected citrus nursery trees by theoretical pigment absorption curves to determine the composition and by infective Asian citrus psyllid, the insect vector. Recently, the of photopigments present and related to behavioral responses of psyllids. Texas Department of Agriculture initiated regulations requiring This information can be used to enhance visual surveillance traps’ commercial and retail citrus nurseries in Texas to transition from effectiveness and optimize use of visual deterrents. traditional open-field to enclosed facilities with insect-resistant screens to mitigate the risk of nurseries serving as sources of CLas. Although Strategies for monitoring of plant epidemics in trade networks V ALONSO CHAVEZ1, F Van Den Bosch1, and S Parnell1 several nursery production facilities have adopted this regulation, 1 non-enclosed nurseries continue to exist and pose a significant threat to Department of Computational and Systems Biology, Rothamsted Research, Harpenden, AL5 2JQ, UK. the citrus industry as potential sources of CLas during this transition period. A systematic survey for HLB was embarked on in a semi-open The global movement of plants and plant products across the globe has nursery facility in South Texas in April 2014. Leaf tissue samples taken increased in recent years, triggering an increase of introduced plant from 94 trees representing 5% of the total number of potted trees in that pathogens. Tree nurseries importing material from abroad may play a nursery were tested for CLas by quantitative and conventional PCR role in the introduction and spread of tree diseases. One example is the assays. Of 94 trees tested, 3.2% (3 trees) tested positive for CLas using spread of sudden oak death in North America and Europe. A more recent both assays. The presence of CLas in the PCR-positive samples was example suggests that ash dieback could have been introduced into the confirmed by multi-locus sequence analyses. The results represent the UK through nursery trade, as well as through aerial spread. first report of HLB in a nursery facility in Texas and underscore the need Huanglongbing disease is also believed to be the direct result of human for more intensive surveillance for HLB in citrus nursery stocks as an movement of plant material. The economic, environmental, and social integral component of HLB mitigation efforts in Texas. cost associated with the spread of invasive pathogens become considerably larger as the incidence of the pathogen increases. To HLB-infected citrus tree physiology and plant growth regulator control the movement of pathogens across the plant trade network, it is effects on preharvest fruit drop crucial to develop efficient sampling and monitoring programmes at key G ALBRIGO points of the network. By detecting the introduction of invasive University of Florida, IFAS/CREC, 700 Experiment Station Road, Lake pathogens at low incidence, the control and eradication of an epidemic is Alfred, 33850 FL. more likely to be successful. Here, we develop a simple epidemiological Since HLB has become widely spread through most Florida citrus trees, model to detect and trace the dynamics of an invasive plant pathogen in preharvest fruit drop has become a major problem for the past two a plant nursery. Using statistical methods, we can predict the epidemic harvest seasons. Trees declining from HLB have greater drought stress incidence given that a detection of the pathogen has occurred for the first and higher percentage fruit drop than healthier trees even though they time. Equally, we trace forward the probability of pathogen movement have fewer leaves. Declining trees had 8 to 12 bars more water stress into another part of the trade network. We explore the effect of these and 10 to 14% more fruit drop than healthier, full canopy trees. In the results on data for Ash dieback in the UK and Huanglongbing disease in 2013‐14 harvest season GA3, Citrus Fix (2, 4‐D), ProMaxa (NAA), Florida. These results provide new insight for the design of monitoring Retain (AVG), 1‐MCP, and s‐ABA were evaluated for their ability to strategies at key points of the trade network. reduce preharvest fruit drop. No treatment significantly reduced fruit drop from the Control level, although GA3 plus 2, 4‐D often had Assessment of the supply of metal micronutrients on HLB-infected numerically less drop than the Control, usually 5 to 7% less. In the 2014‐ trees 1 1 2 1 15 season, larger plots of GA3 plus 2, 4‐D were applied as well as plots FV de Alvarenga , HD Coletta Filho , JRS Lopes , RM Boaretto , JA 3 1* of the strobilurin Headline. Results are reported. Quaggio , and D MATTOS JR 1 Centro de Citricultura “Sylvio Moreira” (IAC), Cordeirópolis-SP, 2 Spectral sensitivity of the Asian citrus psyllid, Diaphorina citri Brazil; Escola Superior de Agricultura “Luiz de Queiroz” (USP), 3 SA ALLAN Piracicaba-SP, Brazil; Centro de Solos e Recursos Agrombientais * USDA/ARS Insect Behavior and Biocontrol Research Unit, Gainesville, (IAC), Campinas-SP, Brazil; with CNPq research grant. FL. The occurrence of the Huanglongbing (HLB) in citrus has caused significant fruit losses because of the severity of the disease and the lack The Asian Citrus psyllid, Diaphorina citri, as a vector of the bacteria of effective control. Spray of nutrients to the leaves and more recently causing citrus greening, is considered one of the most important citrus the application to the soil have been employed in an attempt to mitigate pests globally. Movement of infected psyllids onto uninfected young the effects of the disease on citrus groves. In this context, this study citrus remains a key concern for the maintenance of citrus production. evaluated the growth of young sweet orange trees infected with iocv_journalcitruspathology_30222 1/49 IRCHLB IV / Abstracts of Presentations / Journal of Citrus Pathology ‘Candidatus Liberibacter asiaticus’ (Las) by over-grafting and healthy compared to that on Troyer-1459. In our present study, using ACP adults ones. Plants were supplied either with foliar applications or via substrate caged on the central leaflet, fewer stylet sheaths were formed in the (check non-fertilized, Cu, Mn, Zn or Cu + Zn + Mn) with copper midrib and fewer stylet sheath termini reached the vascular bundle hydroxide, manganese sulphate, and/or zinc sulphate solutions. The (phloem and/or xylem) in UN-3881 compared to Troyer-1459 plants. nutrient applications were at intervals of 30 days in a period of 12 Furthermore, in midribs of UN-3881, the fibrous ring (sclerenchyma) months, and the treatments effects were evaluated at 180, 270, and around the phloem was significantly wider (thicker) compared to that in 360 days after inoculation (DAI) with Las. The nutritional status of Troyer-1459. Our data indicate that feeding and/or probing by ACP plants was evaluated, also the production of dry matter of leaves, adults into the vascular bundle is less frequent in the more resistant (UN- branches and roots, leaf area, specific leaf weight, starch, chlorophyll 3881) than