Commercial Citrus Species Research Articles

Yield and Heat Unit Requirements for Several Citrus Cultivars over Several Seasons in Egypt

Citrus cultivars have various temperature needs for development and output at different times from flowering to harvesting, making climate one of the numerous factors that affect citrus’ productivity and quality. In this study, the yield and heat unit requirements for several commercial citrus species over several seasons from 2010/2011 to 2021/2022 in Egypt were investigated. For this investigation, the time of flowering and the time of fruit harvesting were recorded. However, the required heat units from flowering to fruit harvesting were calculated based on daily records of air temperature, taking into account that all results below zero (negative results) are not used and all maximum air temperatures above 35.0 °C (≥35.1) are changed to 35.0 °C. In addition, the base air temperature of 13.0 °C was utilized for determining the required heat units. The results showed that in the experimental area, the overall mean of minimum air temperature, maximum air temperature, air relative humidity, and precipitation during the experimental periods had values of 15.2 °C, 28.70 °C, 59.3%, and 0.3 mm/day, respectively. Moreover, the lowest number of days required from flowering to fruit harvesting was observed to be 290.0 days for Fremont mandarin. Furthermore, the highest number of days required from flowering to fruit harvesting was observed to be 482 and 440 days, respectively, for Bearss Seedless lime and Valencia orange. Our study has highlighted a notable diversity among the investigated citrus cultivars, particularly highlighting specific cultivars that possess high yield. The cultivar that shows the greatest yield over the investigated seasons of the study was Valencia orange with 147.6 kg/tree. Moreover, the average values of the heat unit requirements for Washington Navel orange, Valencia orange, Murcott mandarin, Fremont mandarin, and Bearss Seedless lime were 3112.7, 3628.3, 3221.9, 3027.6, and 4398.4 °C day, respectively. This is the first report regarding the heat unit’s determination for several citrus cultivars grown in Egypt, and we expect this research will provide a new awareness in accepting and discovering novel locations where citrus cultivars can be positively developed in Egypt. It will also prove to be a source of basic information for the development of the citrus crop model.

Real-time on-site detection of the three 'Candidatus Liberibacter' species associated with HLB disease: a rapid and validated method.

Huanglongbing (HLB) is a devastating disease that affects all commercial citrus species worldwide. The disease is associated with bacteria of three species of the genus 'Candidatus Liberibacter' transmitted by psyllid vectors. To date, HLB has no cure, so preventing its introduction into HLB-free areas is the best strategy to control its spread. For that, the use of accurate, sensitive, specific, and reliable detection methods is critical for good integrated management of this serious disease. This study presents a new real-time recombinase polymerase amplification (RPA) protocol able to detect the three 'Ca. Liberibacter' species associated with HLB in both plant and insect samples, validated according to European and Mediterranean Plant Protection Organization (EPPO) guidelines and tested on 365 samples from nine different geographic origins. This new protocol does not require nucleic acid purification or specialized equipment, making it ideal to be used under field conditions. It is based on specific primers and probe targeting a region of fusA gene, which shows a specificity of 94%-100%, both in silico and in vitro, for the 'Ca. Liberibacter' species associated with HLB. The analytical sensitivity of the new protocol is excellent, with a reliable detection limit in the order of 101 copies per microliter in HLB-infected plant and insect material. The repeatability and reproducibility of the new methods showed consistent results. Diagnostic parameters of the new RPA protocol were calculated and compared with the gold standard technique, a quantitative real-time PCR, in both crude extracts of citrus plants and insect vectors. The agreement between the two techniques was almost perfect according to the estimated Cohen's kappa index, with a diagnostic sensitivity and specificity of 83.89% and 100%, respectively, and a relative accuracy of 91.59%. Moreover, the results are obtained in less than 35min. All these results indicate the potential of this new RPA protocol to be implemented as a reliable on-site detection kit for HLB due to its simplicity, speed, and portability.

PM 7/31 (2) Citrus tristeza virus

<scp>PM</scp> 7/31 (2) Citrus tristeza virus

Temporal Analysis of Candidatus Liberibacter asiaticus in Citrandarin Genotypes Indicates Unstable Infection

Background: Huanglongbing (HLB) is currently one of the most devasting diseases in citrus plants worldwide. Resistance against its causal agent, Candidatus Liberibacter asiaticus (CLas), in commercial Citrus species remains a challenge, even though they show differences in CLas multiplication. Methods: A total of 14 citrandarins and their parents (Sunki mandarin and Poncirus trifoliata cv. Rubidoux) were top-grafted onto the canopy of potted ‘Valencia’ sweet orange plants with high CLas titers. The grafted genotypes were tested for CLas infection and physiological effects of the disease (starch accumulation and callose deposition) for 12 months. Results: All tested genotypes were infected by CLas during the time frame of the experiment. However, a decrease in the infection rate ranging from 50% to 80% for the hybrids H109, H126, H157, and H222 was observed 360 days from the top-grafting. CLas was undetected by real-time PCR in H106 at the end of the experiment, which had low levels of starch and callose deposition. Conclusions: CLas infected all of the tested citrandarins, but a decrease in the infection rate over time was detected for some specific genotypes, which led to less starch accumulation and callose deposition.

Molecular and biological characterization of ‘Candidatus Phytoplasma aurantifolia’ strains infecting commercial citrus species in Iran

In a 2017 survey, witches’ broom disease (WBD) of Mexican lime (WBDL), Bakraee (WBDB), grapefruit (WBDGF), Kinnow (WBDK), Orlando tangelo (WBDOT), Minneola tangelo (WBDMT), sweet oranges varieties Valencia (WBDVSO) and a local (WBDLoSO) were observed in the Hormozgan province of Iran. The agents of citrus WBD were graft transmitted to lime seedlings and from lime seedlings to periwinkle plants via dodder. The work revealed that disease symptoms in lime seedlings and periwinkle plants are biological features for differentiating 16SrII-B and 16SrII-C strains. Phylogenetic and Tsp509I enzyme virtual RFLP analyses and presence of the ‘Candidatus Phytoplasma aurantifolia’ (16SrII-B) signature revealed that phytoplasmas detected in the present study and those from WBDVSO, WBDOT and WBD of citron (Kerman province, Iran) previously reported as 16SrII-C phytoplasma strains, are members of 16SrII-B subgroup. WBDK, WBDOT, WBDMT, WBDVSO and WBDLo association with 16SrII-B phytoplasmas is reported for the first time in the world.

Effect of temperature on symptom expression of witches’ broom disease in commercial citrus species

Effect of temperature on symptom expression of witches’ broom disease in commercial citrus species

PM 7/121 (2) ‘Candidatus Liberibacter africanus’, ‘Candidatus Liberibacter americanus’ and ‘Candidatus Liberibacter asiaticus’

Specific scopeThis Standard describes a diagnostic protocol for ‘Candidatus Liberibacter africanus’, ‘Candidatus Liberibacter americanus’ and ‘Candidatus Liberibacter asiaticus’.1This Standard should be used in conjunction with PM 7/76 (5) Use of EPPO diagnostic protocols.Specific approval and amendmentFirst approved in 2014–09. Revised in 2021–04.

Pest survey card on Phyllosticta citricarpa

The European Commission requested EFSA (M-2017-0137) to assist the Member States to plan annual survey activities of quarantine organisms using a statistically sound and risk-based pest survey approach, in line with current international standards. Phyllostictacitricarpa is a Union quarantine pest and the causal agent of citrus black spot (CBS). It is not known to occur in the EU so special requirements for the import of its host plants and fruit from third countries are in place to prevent its introduction and spread. P. citricarpa produces asexual pycnidia and pycnidiospores on fruit lesions, twigs and leaf litter, but it can also reproduce sexually, giving rise to pseudothecia and ascospores, which are particularly important for long-range dissemination. Most commercial citrus species are susceptible to CBS. Due to the variety of environments in which the fungus is currently distributed, all citrus-growing areas in the EU are potentially suitable for the establishment of the pest. The main pathways for its introduction and spread include production, handling and transport of infected plants for planting or fruit. The goal of the visual examination is to detect the symptoms caused by P. citricarpa. Since symptoms are non-specific and may be highly variable, visual examination should be followed by laboratory testing. Moreover, CBS has a long incubation period and infected fruit may still be asymptomatic at maturity. In this case, symptom induction methods or other early detection approaches (e.g. airborne spore traps or rain collectors for splash-dispersed conidia) could be further explored. For symptomatic fruit, three mainmethods foridentifyingP. citricarpain the laboratoryare presented.Based on the analyses of the information on the pest–host plant system, the variousunits that are needed to design asurvey should be defined and tailored to the situation of each Member State.

Diversity and copper resistance of Xanthomonas affecting citrus

Since citrus canker was first described in the early 1900’s, four major types and three species of pathogenic xanthomonads associated to citrus were identified based on the characteristic symptoms and host range. Type A, caused by X. citri subsp. citri, develops typical raised cankered lesions and is pathogenic on most commercial citrus species and cultivars. Types B and C are caused by X. citri pv. aurantifolii which elicits canker lesions. Besides the typical type A, the more aggressive and most widely spread type, other subtypes have been described, such as type A*, type Aw, type A-Manatee, type A-Miami, type A-minus pthA, and type-A etrog. The type B strains are found only in Argentina and are more pathogenic on lemon and less aggressive on sweet orange, tangerines and grapefruit. The type C strains are found only in Brazil and are pathogenic only on Key lime. X. alfalfae subsp. citrumelonis, formerly known as type E, causes citrus bacterial spot and is more aggressive on trifoliate citrus and its hybrids. Lesions caused by citrus bacterial spot are flat or sunken and not raised. Several subtypes of X. citri subsp. citri have also been identified. Besides the differences in pathogenicity, xanthomonads may also vary in their sensitivity to copper. Copper resistance has been reported for strains of X. citri subsp. citri and X. alfalfae subsp. citrumelonis and is conferred by the gene clusters copLAB or copABCD. Resistance to copper has serious implications for the use of copper-based bactericides, which are the most important chemicals for the control of diseases caused by Xanthomonas on citrus.

Coordination of multiple regulation pathways contributes to the tolerance of a wild citrus species (Citrus ichangensis ‘2586’) against Huanglongbing

Huanglongbing (HLB), a highly destructive disease of citrus production worldwide, is presumably caused by ‘Candidatus Liberibacter asiaticus’ (CLas) because Koch's postulates have not been fulfilled. No HLB resistant genotypes have been so far identified in commercial citrus species, hindering the development of resistance breeding. China is an important center of citrus germplasm resources with abundant wild citrus species. However, studies on the susceptibility or resistance of these wild citrus and their response mechanisms to CLas infection have been limited. In this study, we evaluated the symptom development and transcriptional differences among two wild citrus species, Citrus ichangensis ‘2586’ and C. daoxianensis, and the highly susceptible C. sinensis. No typical symptoms was observed and much less CLas accumulated in C. ichangensis, compared with C. daoxianensis and C. sinensis. Much greater number of differentially expressed genes were identified and pathways were perturbed in diseased C. sinensis, followed by diseased C. daoxianensis then C. sinensis. Many pathways including cell wall, secondary metabolism, stress responses, RNA transcriptional regulation and protein modification were differentially regulated in three diseased citrus species but with different preferences. Particularly, genes associated with carbohydrate metabolism, callose deposition and photosynthesis process were significantly regulated in CLas-infected C. daoxianensis and C. sinensis but not in CLas-infected C. ichangensis. Taken together, it seem to indicate that the relatively successful defenses of C. ichangensis against multiplication of CLas and its symptom development may involve a novel mechanism in which the carbohydrate metabolism and photosynthesis process was balanced with the normal physiology of the plant, and coordinated with other regulation pathways. Evaluation of wild citrus resources to CLas infection is promising for citrus HLB resistance breeding in the future.

Variation in the aggressiveness of Xanthomonas citri subsp. citri pathotypes A and A* on three Citrus species, and epiphytic growth on some citrus weeds

Citrus bacterial canker, caused by Xanthomonas citri subsp. citri (Xcc), is a widespread disease in citrus-producing areas of the tropics and subtropics. It is a serious threat to most commercial citrus cultivars and species. In this study, aggressiveness of different isolates of Xcc was determined on leaves of Citrus aurantiifolia, Citrus limon ‘Eureka’ and Citrus sinensis, and the population dynamics of isolates of two Xcc pathotypes (A and A*) was evaluated on eight plant species considered weeds of citrus, including Amaranthus caudatus, Medicago sativa, Sorghum halepense, Xanthium strumarium, Portulaca oleracea, Avena ludoviciana, Plantago lanceolata and Chenopodium album under greenhouse conditions. Isolates varied from aggressive to weakly aggressive on the basis of the intensity and persistence of water soaking and the development of necrosis 12 days post-inoculation. Both Xcc pathotypes multiplied on all plant species tested except Portulaca oleracea up to 20 days post-inoculation under greenhouse conditions. A high bacterial growth rate was observed on Medicago sativa and Plantago lanceolata. Strains of the A* pathotype successfully proliferated on all weeds except Portulaca oleracea, attaining a population density even higher than that of the A pathotype. The results clearly suggest that weed management is an important strategy in controlling canker disease in citrus-growing areas.

2019–2020 Florida Citrus Production Guide: Citrus Black Spot

Citrus black spot is caused by the fungus Phyllosticta citricarpa (formerly Guignardia citricarpa). The disease causes fruit blemishes and significant yield losses, especially on sweet oranges. Black spot can affect all commercial citrus species and cultivars commonly grown in Florida. This 8-page fact sheet is part of the 2019–2020 Florida Citrus Production Guide. Written by M. M. Dewdney, T. S. Schubert, M. R. Estes, P. D. Roberts, and N. A. Peres, and published by the Plant Pathology Department, March 2019. PP279/CG088: 2022–2023 Florida Citrus Production Guide: Citrus Black Spot (ufl.edu)

Reaction of some commercial citrus species and Iranian lime biotypes to witches' broom disease of lime

Witches' broom disease of lime (WBDL), associated with Candidatus Phytoplasma aurantifolia, has devastated the majority of Mexican lime orchards in southern Iran. Recognition of resistant cultivars and rootstocks can play a major role in WBDL management. In this study, graft-inoculation was used to address the reaction of 12 citrus commercial species and 39 collected lime biotypes from five main lime production areas of Hormozgan province, Iran, against WBDL phytoplasma. The experimental plants were allowed to grow from seed, then five seedlings of each species and biotypes were grafted with Ca. Phytoplasma aurantifolia infected shoots. Inoculated plants were inspected for symptom expression for two years. Direct and nested-PCR using P1/P7 and R16F2n/R16R2 primer pairs, respectively, were used for confirmation of phytoplasmal infection in the suspected plants. All commercial citrus species and 39 of the lime biotypes showed the symptoms of little leaf, internode shortening and witches' broom after two to twenty months from graft-inoculation. Incubation period in plants varied from two months in Astaraei lemon and R11 biotype of Rudan region to twenty months in S4 and S6 biotypes of Senderk region. With these results, we can say all commercial citrus species were sensitive to WBDL. Among the commercial citrus species, Lisbon lemon, grapefruit and Cleopatra mandarin cultivars showed symptoms of WBDL after 460, 425 and 375 days, respectively. Disease symptoms developed rapidly on Astaraei lemon and Bakraei within 85–105 days, respectively. Among the collected biotypes, one, five and one biotypes from Minab, Rudan and Hashtbandi, respectively, were resistant to WBDL phytoplasma. These biotypes were symptomless; however, the PCR assay for detection of the phytoplasma was positive in all of them. These results are promising regarding the potential of using the suitable biotypes to reduce the development of WBDL.

2018–2019 Florida Citrus Production Guide: Citrus Black Spot

Citrus black spot is caused by the fungus Phyllosticta citricarpa (formerly Guignardia citricarpa). The disease causes fruit blemishes and significant yield losses, especially on sweet oranges. Black spot can affect all commercial citrus species and cultivars commonly grown in Florida. This 7-page fact sheet is part of the 2018–2019 Florida Citrus Production Guide. Written by M. M. Dewdney, T. S. Schubert, M. R. Estes, P. D. Roberts, and N. A. Peres, and published by the Plant Pathology Department, May 2018. PP279/CG088: 2022–2023 Florida Citrus Production Guide: Citrus Black Spot (ufl.edu)

Genetic variation and population structure of Diaphorina citri using cytochrome oxidase I sequencing.

Citrus greening disease, or huanglongbing (HLB), is currently one of the most devastating diseases of citrus. The bacteria thought to be responsible for the disease, Candidatus Liberibacter asiaticus impact the majority of commercial citrus species worldwide. These bacteria are transmitted by the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, which is now found in most citrus growing regions. With no known cure, ACP-vectored HLB is responsible for significant economic losses to the global citrus industry. A better understanding of the global genetic diversity of D. citri would improve current and future pest management and mitigation programs. To assess the genetic diversity of D. citri in worldwide collections, a total of 1,108 sequences belonging to ACP gathered from 27 countries in the Americas, the Caribbean, Southeast and Southwest Asia were examined for the study. 883 D. citri came from 98 locations in 18 different countries, and were sequenced using a 678bp fragment of the mitochondrial cytochrome oxidase I (COI) gene. Additionally, 225 previously-reported D. citri COI sequences, were also included in our analysis. Analyses revealed 28 haplotypes and a low genetic diversity. This is in accordance with previous reports on the little diversity of D. citri in worldwide populations. Our analyses reveal population structure with 21 haplotypes showing geographic association, increasing the resolution for the source estimation of ACP. This study reveals the distribution of haplotypes observed in different geographic regions and likely geographic sources for D. citri introductions.

Functional Characterization of a Flavonoid Glycosyltransferase in Sweet Orange (Citrus sinensis).

Fruits of sweet orange (Citrus sinensis), a popular commercial Citrus species, contain high concentrations of flavonoids beneficial to human health. These fruits predominantly accumulate O-glycosylated flavonoids, in which the disaccharides [neohesperidose (rhamnosyl-α-1,2-glucose) or rutinose (rhamnosyl-α-1,6-glucose)] are linked to the flavonoid aglycones through the 3- or 7-hydroxyl sites. The biotransformation of the flavonoid aglycones into O-rutinosides or O-neohesperidosides in the Citrus plants usually consists of two glycosylation reactions involving a series of uridine diphosphate-sugar dependent glycosyltransferases (UGTs). Although several genes encoding flavonoid UGTs have been functionally characterized in the Citrus plants, full elucidation of the flavonoid glycosylation process remains elusive. Based on the available genomic and transcriptome data, we isolated a UGT with a high expression level in the sweet orange fruits that possibly encodes a flavonoid glucosyltransferase and/or rhamnosyltransferase. Biochemical analyses revealed that a broad range of flavonoid substrates could be glucosylated at their 3- and/or 7-hydrogen sites by the recombinant enzyme, including hesperetin, naringenin, diosmetin, quercetin, and kaempferol. Furthermore, overexpression of the gene could significantly increase the accumulations of quercetin 7-O-rhamnoside, quercetin 7-O-glucoside, and kaempferol 7-O-glucoside, implying that the enzyme has flavonoid 7-O-glucosyltransferase and 7-O-rhamnosyltransferase activities in vivo.

History of Gulf Coast Citrus

Alabama, Louisiana, and Mississippi are not often thought of as citrus-producing states. However, citrus has been grown in the coastal regions of these states since the late 19th century. With a climate cool enough for a suitable amount of acid to remain in the fruit for optimum flavor and for adequate peel color development, the northern coastal fringe of the Gulf of Mexico from Louisiana to northwestern Florida is particularly well suited for production of the satsuma mandarin (Citrus unshiu Marc.), one of the most cold-hardy commercial citrus species. There were once thousands of hectares of satsumas planted in this region. Although satsumas typically reach optimum eating quality before fall freezes along the Gulf Coast, periodic severe freezes, as well as the occasional hurricane, prevented a citrus industry of this magnitude from remaining viable. Though freeze injury remains the primary limiting factor for citrus production in this region, there is great local interest, and a small industry focused on local markets has endured. Satsuma remains the primary citrus grown along the Gulf Coast region, though sweet oranges account for a large portion of citrus sales in Louisiana. This paper reviews the history of satsumas on the Gulf Coast, covering past and present production, cultivation, freeze protection strategies, pest issues, and marketing.

Complete Genome Sequences of Six Copper-Resistant Xanthomonas citri pv.citri Strains Causing Asiatic Citrus Canker, Obtained Using Long-Read Technology.

ABSTRACTThe gammaproteobacterium Xanthomonas citri pv. citri causes Asiatic citrus canker. Pathotype A strains have a broad host range, which includes most commercial citrus species, and they cause important economic losses worldwide. Control often relies on frequent copper sprays. We present here the complete genomes of six X. citri pv. citri copper-resistant strains.

First Report of Xanthomonas citri pv. citri Pathotype A Causing Asiatic Citrus Canker in Martinique, France

HomePlant DiseaseVol. 100, No. 9First Report of Xanthomonas citri pv. citri Pathotype A Causing Asiatic Citrus Canker in Martinique, France PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Xanthomonas citri pv. citri Pathotype A Causing Asiatic Citrus Canker in Martinique, FranceD. Richard, C. Boyer, S. Javegny, K. Boyer, P. Grygiel, O. Pruvost, A. L. Rioualec, V. Rakotobe, J. Iotti, R. Picard, C. Vernière, C. Audusseau, C. François, V. Olivier, A. Moreau, and A. ChabirandD. RichardSearch for more papers by this author, C. BoyerSearch for more papers by this author, S. JavegnySearch for more papers by this author, K. BoyerSearch for more papers by this author, P. GrygielSearch for more papers by this author, O. PruvostSearch for more papers by this author, A. L. RioualecSearch for more papers by this author, V. RakotobeSearch for more papers by this author, J. IottiSearch for more papers by this author, R. PicardSearch for more papers by this author, C. VernièreSearch for more papers by this author, C. AudusseauSearch for more papers by this author, C. FrançoisSearch for more papers by this author, V. OlivierSearch for more papers by this author, A. MoreauSearch for more papers by this author, and A. ChabirandSearch for more papers by this authorAffiliationsAuthors and Affiliations D. Richard C. Boyer S. Javegny K. Boyer P. Grygiel O. Pruvost , CIRAD UMR PVBMT, F-97410 Saint-Pierre, La Réunion, France A. L. Rioualec V. Rakotobe J. Iotti , DAAF Service de l’Alimentation, F-97264 Fort de France, Martinique R. Picard , FREDON, F-97224 Ducos, Martinique C. Vernière , CIRAD UMR BGPI, F-34398 Montpellier Cedex 5, France C. Audusseau C. François V. Olivier , ANSES Laboratoire de la Santé des Végétaux, F-49044 Angers, France A. Moreau A. Chabirand , ANSES Laboratoire de Santé des Végétaux, F-97410 Saint-Pierre, La Réunion, France. Published Online:17 Jun 2016https://doi.org/10.1094/PDIS-02-16-0170-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Asiatic canker, caused by Xanthomonas citri pv. citri, is a major threat to worldwide citriculture. Three pathotypes differing in host range and hypersensitive reactions toward citrus species have been defined. Whereas pathotypes Aw and A* have a restricted host range, X. citri pv. citri pathotype A infects a broader range including most commercial citrus species and hybrids and can cause important economic losses in tropical and subtropical areas. Pathotype A strains, especially those assigned to lineage 1, were implicated in the major geographical expansion of X. citri pv. citri during the 20th century from their native area, Asia (Pruvost et al. 2014). X. citri pv. citri is listed as a quarantine pathogen in the European Union (EU) – Directive 2000/29/EC annex II A1. Martinique (France) is an outermost region of the EU in the eastern Caribbean Sea. Canker lesions were first observed at Morne Rouge, Martinique in June 2014 on grapefruit (Citrus paradisi), mandarin (C. reticulata), Tahiti lime (C. latifolia), and Valencia and Washington Navel oranges (C. sinensis). Official diagnostics, including bacterial isolations on YPGA or KC semiselective medium (Pruvost et al. 2005), PCR-based identification with 4/7 primers (Hartung et al. 1993), and pathogenicity tests, were performed following the EPPO standard PM7/44 (www.eppo.int) and identified isolates as X. citri pv. citri. Three strains isolated in Martinique in 2014 from grapefruit or Tahiti lime were further characterized (LL074-4, LL077-2, and LL079). Multilocus sequence analysis (MLSA) targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (Almeida et al. 2010; Bui Thi Ngoc et al. 2010) identified Martinique strains as X. citri pv. citri with 100% sequence identity to the type strain LMG 9322. Using MLVA-31 targeting 31 minisatellites, Martinique strains were assigned to lineage 1 composed of pathotype A strains (Pruvost et al. 2014). All strains were inoculated by a detached leaf assay onto Mexican lime SRA 140 (C. aurantifolia), sweet orange Washington Navel SRA 102, and grapefruit Henderson SRA 336 (Bui Thi Ngoc et al. 2010). All inoculated leaves produced typical erumpent, callus-like tissue at wound sites. Xanthomonas-like colonies were reisolated from lesions that had developed. Boiled suspensions were assayed by PCR with 4/7 primers and produced the expected amplicon, fulfilling Koch’s postulates. No lesions developed on the negative control consisting of sterile 0.01M tris buffer pH 7.2. This is the first report of X. citri pv. citri in Martinique and to our knowledge in the Caribbean region. Surprisingly, all strains collected to date in Martinique grew on YPGA supplemented with 300 mg liter−1 copper sulfate even when no extensive copper spray programs have been used, suggesting that copper-resistant strains may have been introduced. Disease is contained by tree removal and burning and the situation is presently under apparent control although positive trees were sporadically detected in 2015 in backyards or small orchards at Le Lorrain and Saint Pierre. An extensive surveillance program is currently implemented in Martinique for quarantine pathogens of citrus.

Influence of Citrus Species To Biology And Development of Citrus Silver Mite Polyphagotarsonemus latus (Banks) (Acari:Tarsonemidae)

Citrus Silver Mites (CSM) Polyphagotarsonemus latus (Banks) in Indonesia has been known as a major pest of tea plant, sesame and jatropha. Recently CSM was found attacking citrus plant. Plant damage caused by mites on the leaf buds are curved, curly shoots and dead ends. This condition was found in the screen house of some nurseries for several citrus varieties. Because of the damage, the control anticipation based on bioecology must be taken seriously. The study was conducted on the biology and development of CSM on three commercial citrus species that were Tangerine, Sweet Orange and Mandarin. The results showed that in general, CSM life cycle on three citrus species was not significantly different, which was about 5 days. Pre oviposition period, oviposition period, longevity of adult female, post oviposition period did not differ between the three citrus species. The fecundity of CSM on Sweet Orange was higher than that of Tangerin and Mandarin which were respectively 41.22 ; 26.22 and 29.32 eggs per female. Sex ratio was 1:4,75 on Tangerin, Sweet Oranges and the Mandarin were respectively 1:405 and 1:4.68.