Progress 09/15/06 to 09/14/09
Outputs
OUTPUTS: 1)Potential for bacterial survival in infected citrus fruit lesions and as surface contaminants on symptom-free fruit was investigated. Experiments demonstrated that harvested and packinghouse-disinfested citrus fruit are extremely unlikely to be a pathway for Xanthomonas citri subsp. citri to reach and infect susceptible citrus and become established in canker-free areas. 2)Copper-based bactericides are necessary to protect fruit as they grow from 2 cm in diameter to full expansion. To control disease on fruit, copper must be applied every 21 days which can require 10 or more spray applications per season for grapefruit. Effectiveness of copper is overcome by wind-blown rain in excess of 8 m/sec that occurs frequently during the tropical weather season in Florida. Copper has other possible disadvantages including phytotoxicity to the peel, the development of resistance in xanthomonad populations and the accumulation of copper in soils with potential environmental impacts. Streptomycin is an alternative contact bactericide found to be effective, but the risk of development of antibiotic resistance in bacterial populations will limit its use in spray programs. Soil applications of systemic insecticides and other chemical inducers of systemic aquired resitance produce season-long control of citrus canker in non-bearing young trees. The activity of chemical SAR inducers does no always match that of copper and will not be feasible for use on fruiting trees. 3)Alternatively, SAR expression in susceptible citrus varierties may be altered by genetic manipulation of NPR1, a regulator of SAR responses. Arabidopsis NPR1 is highly effective for reduction of bacterial multiplication and lesion severity for several transgenic lines of Duncan grapefruit and Hamlin orange. As a non transgenic approach to introduction of canker reisitance somatic cybridization has been used to combine cell culture protoplasts of the maternal Meiwa kumquat (Fortunella, resistant to canker) with leaf protoplasts of rough lemon (susceptible to canker). The phenotype of resistance in kumquat has been identified as a hypersensitive response and in the rough lemon cybrid resembles that of a high level of resistance. To work with limited amounts of leaf tissue from tissue culture derived plants an in vitro detached leaf assay has been developed to conduct experiments under quarantine conditions in a growth chamber. 4) Prior to the widespread distribution of canker in FL, growers and researchers traveled to canker endemic areas of Brazil and Argentina to learn about canker management in groves and packinghouses. Since 2005, the canker education program has employed one full-time coordinator to work with citrus county agents in educational programs that are delivered at statewide grower meetings. PARTICIPANTS: Collaborators: Univdrsity of Florida, Depts. of plant Pathology and Micobiology and Cell Science, Gainesville, FL; USDA-ARS, US Horticultural Research Laboratory,Fort Pierce, FL; Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL; USDA-ARS, San Joaquin Valley Agricultural Sciences Center, Parlier, CA; Southern Gardens Citrus, US Sugar Corporation, Clewiston, FL; IAPAR, Londrina, Brazil; USDA-APHIS, Plant Health Science and Technology, Edinburg, TX; EEAOC, Las Talitas, Tucuman, Argentina; USDA-APHIS, Citrus Health Response Program, Orlando, FL; Fundecitrus, Araraquara, Sao Paulo, Brazil; Training: 4 postdocs at Citrus Research and Education Center, Lake Alfred, FL 3 graduate students at Citrus Research and Education Center TARGET AUDIENCES: USDA-APHIS, Plant Protection and Quarantine; Florida, Brazilian and Argentine citrus industry protocols for mananging citrus canker pre- and postharvest PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
1)In 2009 APHIS modified the rules to allow shipping of canker exposed and symptomatic fruit to citrus-producing states under the standard protocols for fruit disinfection. 2)Currently, the results from field trials in Florida of chemical applications for canker control are being utilized to refine recommendations for canker management and that information is being disseminated in citrus grower publications and the Florida Citrus Pest Management Guide. Streptomycin as an alternative to copper for chemical control for use on grapefruit to reduce risk of phytotoxicity to fruit rind and to augement control during late season tropical weather. Streptomycin is currently under evaluation of fruit residues for the EPA section 18 registation process. 3)NPR1 transgenic lines of grapefruit and Hamlin orange are being propagated for planting in an approved location in Florida for field evaluation of canker resistance. 4)The UF/IFAS Citrus Canker Education Program has employed one full-time coordinator to distribute information on the latest developments in canker management in the form of presentations to the Florida Citrus Production Managers Association, annual citrus grower seminars, and updates for the Florida Citrus Pest Management Guide, citrus industry magazines and in UF Extension bulletins, as well as, handouts and displays. Other activities carried out by the coordinator are updated on the website http://canker.ifas.ufl.edu hosted by CREC.
Publications
- Behlau, F., Belasque J., Jr., Graham, J.H., Leite Jr. R.P. 2009. Effect of frequency of copper applications on control of citrus canker and the yield of young bearing sweet orange trees. Crop Protection 28 (accepted).
- Francis, M. I., Redondo, A., Burns, J. K., & Graham, J. H. 2009 Soil application of imidacloprid and related SAR-inducing compounds produces effective and persistent control of citrus canker. Europ. J. Plant Path. 124:283-292
- Gottwald T., Graham, J., Bock, C., Bonn, G., Civerolo, E., Irey, M.,. Leite, R. Lopez, M, McCollum, G., Parker, P., Ramallo, J., Riley, T., Schubert, T., Stein B., Taylor, E. 2009. The epidemiological significance of post-packinghouse survival of Xanthomonas citri ssp. citri for dissemination of Asiatic citrus canker via infected fruit. Crop Protection 28:508-524.
- Dewdney, M. M. and J. H. Graham. 2009. Citrus Canker. Citrus Pest Management Guide, SP-43. IFAS, Univ. Florida. M.E. Rogers, M. M. Dewdney, and T. M. Spann (eds.). p. 115-119. PP-182.
- Behlau, F., J. H. Graham, and J. B. Jones. 2009. Monitoring resistant populations of Xanthomonas citri subsp. citri and epiphytic bacteria on young citrus trees treated with copper or streptomycin. Phytopathology 99: S10.
- Dewdney, M. M., Roberts, P. D., Graham, J. H., Chung, K.-R. and Zekri, M. 2009. Homeowner fact sheet: Citrus canker (PP194). Gainesville: IFAS, Univ. Florida. (In press).
- Graham, J. and Dewdney, M. 2009. Management recommendations for citrus canker in 2009. Citrus Industry 90(2): 22-25, 31.
- Bock, C. H., P. E. Parker, A. Z. Cook, J. H. Graham, and T. R.Gottwald. 2009. Efficacy of Cankerguard sprays for effective decontamination of citrus canker. Phytopathology 99: S13.
- Dutt, M., G. Barthe, M. Francis, J. Graham, and J. Grosser. 2009. Resistance to bacterial spot can be correlated with resistance to canker in transgenic citrus. Phytopathology 99: S30.
- Francis, M. I., A. Pena, I. Kostenyuk, J. Burns, and J. H. Graham. 2009. HR-like resistance of kumquat (Fortunella spp.) to citrus canker caused by Xanthomonas citri sbsp. citri. Phytopathology 99: S36.
- Graham, J. and M. Myers. 2009. Soil drenches of imidacloprid, thiamethoxam and acibenzolar-S-methyl for induction of SAR to control citrus canker in young citrus trees. Phytopathology 99: S46.
- Guo, Y., U. S. Sagaram and N. Wang 2009. The galU gene is required for survival of Xanthomonas axonopodis pv. citri in planta and its pathogenicity. Phytopathology 99:S48
- Figueiredo J., G. Minsavage, F. White, J. Graham, and J. Jones. 2009. An unknown type three secretion independent HR-elicitor from Xanthomonas citri subsp. citri. XIV Int. Cong. on Molecular Plant-Microbe Interactions. Quebec, Canada July 2009. http://www.ismpminet.org/meetings/abstracts/2009/p09ma166.asp
- Figueiredo J., T. Lahaye, P. Roemer, G. Minsavage, F. White, J. Graham, and J. Jones. 2009. Transient expression of avrGf1 in citrus. XIV Int. Cong. on Molecular Plant-Microbe Interactions. Quebec, Canada July 2009. http://www.ismpminet.org/meetings/abstracts/2009/p09ma165.asp
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Progress 09/15/07 to 09/14/08
Outputs
OUTPUTS: In commercial packing lines in Florida and northwest Argentina, pre-washing canker exposed fruit to remove dirt and debris reduced surface populations of Xanthomonas citri subsp. citri (Xcc). Bioassay demonstrated that the highest incidence of Xcc from fruit after the packing line antimicrobial treatment occurred with symptomatic fruit and was zero to very low levels for fruit from apparently healthy trees. As fruit senesced and lesions aged, the ability of fruit to generate Xcc bacteria was increasingly compromised. Discarded canker-infected fruit in cull piles was ineffective as a source of inoculum for dispersal. Transmission from cull piles of packing line processed fruit to surrounding trap plants, even less than 1 m away, did not occur under natural conditions. The systemic insecticide, imidacloprid (Admire, Bayer Crop Science) is a neo-nicotinoid that breaks down in planta into 6-chloronicotinic acid, a compound closely related to the systemic acquired resistance (SAR) inducer isonicotinic acid. Soil drenches of imidacloprid, isonicotinic acid, and acibenzolar-s-methyl induced a high and persistent up-regulation of PR-2 (β-1,3 glucanase) gene expression and reduced the number of canker lesions for up to 24 weeks compared to 4 weeks for foliar acibenzolar-s-methyl. Soil applied inducers of systemic acquired resistance reduced canker lesions up to 70% compared with the untreated inoculated plants. Field trials in Brazil demonstrated that sprays of reduced rates of copper hydroxide (CH) applied a 14 day interval were as effective as the full rate of CH for controlling canker on fruit and reduced canker-induced fruit drop of moderately susceptible sweet orange cultivars. Streptomycin sulphate (SS) was as effective as intermediate rates of CH, whereas oxytetracycline (OT, Mycoshield) was ineffective. At 21-day interval of application, SS combined with reduced rates of CH reduced fruit disease incidence and SS combined or alternated with CH significantly reduced fruit drop. In Florida on white grapefruit, CH and copper sulphate (CS) applied at 14- or 21-day intervals controlled canker on fruit, but caused considerable copper burn to the fruit rind. Alternation of SS with a reduced rate of CS provided a similar reduction in diseased fruit with less copper burn than the full rate of CH or CS. A Xac 306 mutant library was constructed with EZ-Tn5 Tnp Transposome Kit (Epicentre). This mutant library contains 21,000 mutants which is roughly four times coverage of the Xac genes. Currently, screening and identification of virulence related mutants are under way. The genome of Xac Aw was sequenced at ICBR of UF at Gainesville using 454/FLX sequencing. The micro-bead sequence data collected totaled 55,616,480 bp of genomic sequence (average size 222 bp) which is about 10 time coverage of the Aw genome. The draft sequence is 5,227,263 bp and encodes 4745 genes. Microarray analysis of virulence factors of citrus canker strains is under way. Currently, the following mutants were made: rpfF, rpfC, rpfG, and hrpG. A Nimblegen array for Xac A strain was designed and is ready for use. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Florida and international citrus industries. Transfer of information through extension workshops, grower meetings and national/international society meetings PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The risk of introduction of Xanthomonas citri subsp. citri (Xcc) to new, unaffected citrus producing areas is a major concern for those citrus industries attempting to remain free of citrus canker. The potential of Xcc survival in citrus fruit lesions and as surface contaminants on symptom-free fruit as a viable inoculum source was investigated. As anticipated, recovery of Xcc from fruit surfaces increased when active citrus canker lesions were present but total bacterial recovery decreased after packingline processing, and bioassays demonstrated that the quantity of viable Xcc declined as fruit remained in cold storage, or as fruit aged on the trees. Taken as a group, these experiments demonstrate that harvested and packinghouse-disinfested citrus fruit are extremely unlikely to be a pathway for Xcc to reach and infect susceptible citrus and become established in canker-free areas. Soil application of the systemic insecticide imidacloprid (Admire, Bayer Crop Science) produced season-long control of canker caused due the induction of systemic acquired resistance (SAR) over a period of months. Hence, soil application of neonicotinoids insecticides on young trees has a secondary benefit in terms of canker control on foliage and reduction in disease-induced defoliation. Control of canker on fruiting trees can be achieved with the antibiotic streptomycin in combination with reduced rates of copper to minimize risk of phytotoxicity (burn) to the fruit rind, development of bacterial resistance to copper, and to reduce copper accumulation in the soil environment.
Publications
- Behlau, F., Belasque Jr., J., Bergamin-Filho, A., Graham, J.H., Leite Jr., R.P., and Gottwald, T.R. 2008. Copper sprays and windbreaks for control of citrus canker on young orange trees in southern Brazil. Crop Protection 27:807-813.
- Behlau, F., Belasque Jr., J.,Leite Jr., R.P., and Graham, J.H. 2008. Effect of copper spray interval on control of citrus canker for young sweet orange trees. Proc. Intern. Soc. Citriculture. Wuhan, China. P. 89.
- Behlau, F., Jones, J. B. and Graham, J. H. 2008. A semiselective medium for isolation of copper and streptomycin resistant strains of Xanthomonas citri sbsp. citri from plant material. Phytopathology 98:S20.
- Figueiredo, J. F., Jones J. B., Graham J. H., F. F. White. 2008. hrpW a virulence factor from Xanthomonas citri sbsp. citri. Phytopathology 98:S53.
- Figueiredo, J. F., Jones J. B., Graham J. H., F. F. White. 2008. Genes of Xanthomonas citri sbsp. citri involved in disease development. Phytopathology 98:S53.
- Francis, M. I.; Graham, J. H. 2008. In vitro inoculation of citrus germplasm for rapid screening of resistance to citrus canker. Phytopathology 98 (6), S55.
- Francis, M. I.; Redondo, A.; Burns, J. K.; Graham, J. H. 2008. Soil application of imidacloprid and related SAR-inducing compounds produces effective and persistent control of citrus canker. Phytopathology 98 (6), S55.
- Francis, M. I., Redondo, A., Burns, J. K., & Graham, J. H. 2009. Soil application of imidacloprid and related SAR-inducing compounds produces effective and persistent control of citrus canker. Europ. J. Plant Path.(in press)
- Gottwald T., Graham, J., Bock, C., Bonn, G., Civerolo, E., Irey, M.,. Leite, McCollum, G., Parker, P., Ramallo, J., Riley, T., Schubert, T., Stein B., Taylor, E. 2009. The epidemiological significance of post-packinghouse survival of Xanthomonas citri sbsp. citri for dissemination of Asiatic citrus canker via infected fruit. Crop Protection (accepted).
- Graham, J. 2008. Best management practices post canker eradication. Phytopathology 98:S196.
- Graham, J. 2008 Management challenges posed by canker for production of highly susceptible grapefruit in Florida. Proc. Intern. Soc. Citriculture. Wuhan, China. P. 94.
- Graham, J., Castle, B. and Spann, T. 2008. Management recommendations for citrus canker and windbreaks. Citrus Ind. 89(4):16-18.
- Graham, J. H., Leite, Jr., R. P., Yonce, H. D., and Myers, M. 2008. Streptomycin controls citrus canker on sweet orange in Brazil and reduces risk of copper burn on grapefruit in Florida. Proc. Fla. State Hort. Soc. 121:(in press).
- Grosser, J.W., M. Francis and J.H. Graham. 2008. Transfer of Canker Resistance from Kumquat to Susceptible Citrus via Somatic Cybridization. HortScience 43:1117.
- Grosser, J. W.; Gmitter, F. G., Jr.; Orbovic, V.; Moore, G. A.; Graham, J. H.; Soneji, J.; Kayim, M.; Gonzalez-Ramos, J.; Mirkov, T. E. 2008. Genetic Transformation of Grapefruit. In A Compendium of Transgenic Crop Plants, Kole, C.; Hall, T. C., Eds. Blackwell Publishing: Oxford, UK; Vol. Volume 5: Tropical and Subtropical Fruits and Nuts, pp 63-76.
- Omar, A. A., Dekkers, M. G. H., Graham, J. H., and Grosser, J. W. 2008. Estimation of transgene copy number in transformed citrus plants by quantitative real-time PCR. Biotechnol. Prog. 24:1241-1248.
- Omar, A. A., Redondo A., Graham, J. H. and Grosser, J. W. 2008. Screening Transgenic Hamlin sweet orange [Citrus sinensis (L.) Osbeck] for Resistance to Citrus Canker.Proc. Intern. Soc. Citriculture. Wuhan, China. P. 293.
- Young, J. M., Allen, C., Coutinho, T., Denny, T., Elphinstone, J., Fegan, M., Gillings, M., Gottwald, T. R., Graham, J. H., Iacobellis, N. S., Janse, J. D., Jacques, M.-A., Lopez, M. M., Morris, C. E., Parkinson, N., Prior, P., Pruvost, O., Rodrigues Neto, J., Scortichini, M., Takikawa, Y., and Upper, C. D. 2008. Plant Pathogenic Bacteria as Biological Weapons: Real Threats Phytopathology 98: 1060-1065.
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Progress 09/15/06 to 09/14/07
Outputs
OUTPUTS: The establishment of citrus canker in Florida, the end of the eradication program in January 2006, and the interim rule on August 1, 2006 that quarantined the entire state of Florida has had an immediate impact on fresh fruit shippers and will impact grove production and profitability of all varieties as the epidemic increases. Presently, shipment of all citrus produced in Florida to citrus-producing states and territories is prohibited whether the fruit shows symptoms or not. Genetically modified strains of Xanthomonas axonopodis pv. citri (Xac) expressing a labile form of green fluorescent protein that breaks down when the bacterium dies have been developed. These strains are employed for monitoring the survival and fate of Xac in and on leaves and fruit. A new dot blot procedure is used to detect Xac among a number of yellow bacterial species on citrus fruit that are capable of survival on semi-selective media, and indistinguishable from Xac. This detection method is
utilized to monitor bacterial survival on asymptomatic fruit in the packinghouse. To identify genes differentially expressed in tolerant vs. susceptible citrus varieties we have employed DNA microarray and subtractive cDNA library technology. Grapefruit a variety susceptible to canker, and kumquat, a resistant species, were inoculated with Xac. Four ESTs were identified that were oppositely regulated in kumquat and grapefruit. QRT-PCR primers were designed to these sequences for the purpose of validating their spatial and temporal expression. CTV-based transient expression vectors were used to express anti-bacterial peptides throughout citrus plants to evaluate the potential for these gene products to produce resistance to canker. These peptides were evaluated against citrus canker and at least three constructs with a leader peptide to export the peptides out of cells are showing positive activity in disease assays. The peptides will be transformed into grapefruit and Hamlin orange
for further evaluation. A seedling pummelo selected in the rootstock breeding program produced fruit with a typical grapefruit size and appearance externally, and deep-red flesh internally. This selection was also significantly resistant, suggesting potential as a breeding parent for fruit quality and canker resistance. Field trials conducted in Brazil demonstrate that even reduced rates of copper formulations are consistently effective. The antibiotic streptomycin sprayed alone or in combination or rotations with copper is as effective as copper and can reduce the risk of copper toxicity to the fruit. Imidacloprid applied as a soil drench has a well-known canker disease control property through control of leafminer to reduce the wounding and exacerbation of the disease by the larval feeding on leaves. There is also a direct systemically acquired (SAR) resistance activity against citrus bacterial disease in the field. Based on the results of field trials, imidacloprid is efficacious
for disease control on young trees when applied at the upper limit of the label rate per tree size and per acre for insect control.
PARTICIPANTS: J. H. Graham, Citrus Research & Education Center, Univ. Florida, IFAS, Lake Alfred, FL; J. K. Burns, Citrus Research & Education Center, Univ. Florida, IFAS, Lake Alfred, FL; W. O. Dawson, Citrus Research & Education Center, Univ. Florida, IFAS, Lake Alfred, FL; J. W. Grosser, Citrus Research & Education Center, Univ. Florida, IFAS, Lake Alfred, FL;F. G. Gmitter, Citrus Research & Education Center, Univ. Florida, IFAS, Lake Alfred, FL; L. W. Timmer, Citrus Research & Education Center, Univ. Florida, IFAS, Lake Alfred; A. Collmer, Cornell Univ., Ithaca, NY; E. Mirkov, Texas A&M Univ., Weslaco, TX; T. R. Gottwald, USDA,ARS,USHRL, 2001 S. Rock Rd., Ft. Pierce, FL; R. P. Leite, Instituto Agronomico do Parana (IAPAR), Londrina, Parana, Brazil; B. Stein, Estacion Experimental Agroindustrial O. Colombres (EEAOC), Tucuman, Argentina; J. Cubero, INIA, Madrid, Spain
TARGET AUDIENCES: In previous extension/education for citrus canker, a DVD, card decks, and other materials were prepared for disease identification and a video on decontamination was made available. In this project, a specialized version of the canker identification DVD was prepared to serve nurseries in English and Spanish. Once it was apparent that many growers were going to have to live with canker, a PowerPoint presentation was prepared. The PowerPoint presentation highlighted recommendations on nursery practices, decontamination, tree removal to reduce inoculum, and use of windbreaks and copper sprays for disease control. Articles were prepared for the Citrus Industry Magazine and EDIS summarizing those recommendations. Five major statewide meetings in February-March 2006 were developed and presented on identification and management of canker. Those were held in Lake Alfred, Ft. Pierce, Immokalee, and Arcadia, and there were 200 participants in the sessions. Similar
presentations were made at a Citrus Squeezer in Immokalee (50 participants), an OJ Break in Bartow (150), an extension meeting in Dade City (17), and at the Indian River Citrus (IRCS) seminar (125). In addition, at the Indian river citrus Seminar, grove workers were trained in procedures for identifying canker (180 English speaking, 220 Spanish speaking). Various other training sessions, 30 programs in total, were organized where for industry personnel for training in early detection and management procedures for canker (500 English speaking and 200 Spanish speaking in total). A day long workshop (60 participants) was held in Lake Alfred on the use of windbreaks for canker control. Material was presented on the advantages and disadvantages of windbreaks, useful tree and shrub species, artificial windbreaks, sources of materials, and other aspects. A notebook was prepared and distributed including all relevant information regarding the use of windbreaks for canker management and is
also available now through UF/IFAS/CREC website.
Impacts
Presently, shipment of all citrus produced in Florida to citrus-producing states is prohibited whether the fruit shows symptoms or not. New regulations are being considered that would allow "asymptomatic fruit" to be shipped to other states regardless of canker presence in the grove. The key goals are demonstrating that current disinfection protocols greatly reduce the risk of Xanthomonas axonopodis pv. citri (Xac) survival on fruit surfaces and that grove and inspections can keep symptomatic fruit out of the packed cartons, regardless of whether the fruit originated from canker infested groves. The Argentina experience indicates if the incidence of infected fruit in a block is greater than perhaps 5%, it will be risky to harvest fruit from that block for fresh market. Thus, reduction of canker incidence on fruit in the groves is an essential first step in producing clean fruit for packing. Copper-based bactericides are a standard chemical control for canker
world-wide. Copper reduces bacterial populations and multiple applications are needed to achieve adequate control on susceptible hosts. Copper-based spray programs are effective when targeted to fruit greater than the 0.75 inches in size. From 2-3 spray applications every 21 days will be required for oranges and tangerines, and in excess of 10 will be required for grapefruit. Since copper diminishes infection by contact of bacteria on surfaces, the effectiveness of copper spray programs is overcome by rains with wind that introduce bacteria directly into stomates. Because of the partial effectiveness of copper under wind-blown rain conditions, grapefruit will require windbreaks for profitable production of fresh fruit for both internal and export markets. Copper has other possible disadvantages after long-term use including resistance to copper in xanthomonad populations and accumulation of copper metal in soils with potential phytotoxic and environmental effects. Other contact
bactericides tested and found to be somewhat effective are antibiotics; but high cost and risk of development of antibiotic resistance within xanthomonad populations will limit their use in spray programs. Systemic bactericides are unknown, but enhancement of innate resistance with soil applied neo-nicotinoid insecticides has shown promise for canker control on young trees. Profitable production of highly susceptible cultivars like grapefruit and early oranges will require strategies to enhance their resistance to canker. Previous studies show that while resistance from kumquat is inheritable and that hybrids with acid fruits (limes) show acceptable resistance, development of such hybrids with commercial grapefruit and oranges are considered unacceptable for the market. Moreover, the source of resistance from kumquat is multigenic, thus more than one transgene in the target variety will be required. In contrast, antimicrobial genes from animal and plant sources have been shown to have
activity in CTV-vectored plants provided the antimicrobial peptides have leader peptide sequences that enhance their export into the intercelleular space where Xac multiplies during the infection process.
Publications
- Behlau, F., Belasque Jr., J., Bergamin-Filho, A., Graham, J.H., Leite Jr., R.P., and Gottwald, T.R. 2008. Copper sprays and windbreaks for control of citrus canker on young orange trees in southern Brazil. Crop Protection: (accepted).
- Stein, B., Ramallo J., Foguet, L., Graham, J. H. 2007. Citrus leafminer control and copper fungicide sprays for management of citrus canker on lemon in Tucuman, Argentina. Proc. Fla. State Hort. Soc. 120:(in press).
- Irey, M., Gottwald, T. R., Graham, J. H., Riley, T. D., and Carlton, G. 2006. Post-hurricane analysis of citrus canker spread and progress towards the development of a predictive model to estimate disease spread due to catastrophic weather events. Online. Plant Health Progress, doi: 10.1094/PHP-2006-0822-01-RS.
- Graham, J. H., Gottwald, T. R., and Leite, R. P., Jr. 2006. Prospects for control of citrus canker with novel chemical compounds. Proc. Fla. State Hort. Soc. 119: 83-88.
- Graham, J. H. and R. P. Leite, Jr. 2007 Soil applied neonicotinoids for control of bacterial diseases on young citrus trees. Proc. Intern. Workshop on PR-Proteins and Induced Resistance Against Pathogens and Insects. Doorn The Netherlands. p. 107.
- Graham, J. H., Gottwald, T. R., and Irey, M. S. 2007. Current Status of Citrus Canker and Haunglongbing epidemics and their management in Florida. Fitolpath. Bras. 32:S101-S102.
- Graham, J. H., Leite, R. P., and Yonce, H. D. 2007. Streptomycin controls citrus canker in Brazil and Florida and reduces risk of copper phytotoxicity on grapefruit. Phytopathology. 97(7):S42.
- Grosser, J.W., Gmitter, F.G. Jr., Orbovic, V., Moore, G.A., Graham, J.H., Soneji, J., Gonzalez-Ramos, J., Mirkov, T.E. and Kayim, M. 2007. Grapefruit. In: Kole, C. and Hall, T.C. (eds.). A Compendium of Transgenic Crop Plants. Volume 5. Wiley-Blackwell (In press).
- Omar, A.A., Dekkers, M.G.H., Graham, J.H., and Grosser, J.W. 2007. Quantitative multiplex real-time PCR as a screening tool for estimating transgene copy number in transgenic Citrus. Proc. Intern. Plant and Animal Genome XIV Conference, San Diego, California, USA. p.702.
- Khalaf, A.A, Moore, G.A. and Gmitter, F.G. Jr. Microarray Expression Profiling of Nagami Kumquat In Response to Canker. Proceedings International Symposium on Biotechnology of Temperate Fruit Crops and Tropical Species 2007. Eds.R.E. Litz and R. Scorza. ISHS Acta Horticulturae 738: 221-224.
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