'Candidatus Phytoplasma costaricanum' a novel phytoplasma associated with an emerging disease in soybean (Glycine max).

A novel phytoplasma, designated strain SoyST1c1, associated with a newly emerging disease in soybean (Glycine max), known as soybean stunt (SoyST), was found in 2002 in a soybean plantation in Alajuela Province, Costa Rica. The same phytoplasma, or a very closely related strain, also infected sweet pepper (Capsicum annuum) with purple vein syndrome (SwPPV) and passion fruit vine (Passiflora edulis) with bud proliferation disease (PasFBP) in the same region. Sequence analysis of cloned 16S rRNA gene sequences (GenBank accession nos FJ226068-FJ226073 and HQ225624-HQ225635) indicated that all three affected plants were infected by phytoplasmas that shared <97.5% sequence similarity with previously described phytoplasmas. The SoyST-causing phytoplasma represents a new taxon, most closely related to phytoplasma group 16SrI and 16SrXII strains. Virtual RFLP analysis indicated that the SoyST-causing phytoplasma and its closely related strains represent a novel 16Sr group, designated 16SrXXXI. Phylogenetic analysis of 16S rRNA gene sequences from the new phytoplasma strains, those previously described as 'Candidatus Phytoplasma spp.' and other distinct, as yet unnamed, phytoplasmas indicated that the SoyST-causing phytoplasma represents a distinct lineage within the aster yellows/stolbur branch on the phylogenetic tree. On the basis of its unique 16S rRNA gene sequence and biological properties, strain SoyST1c1 represents a novel taxon, for which the name 'Candidatus Phytoplasma costaricanum' is proposed with SoyST1c1 as the reference strain.

First Report of New Phytoplasma Diseases Associated with Soybean, Sweet Pepper, and Passion Fruit in Costa Rica.

A new soybean disease outbreak occurred in 2002 in a soybean (Glycine max) plantation in Alajuela Province, Costa Rica. Symptoms on the affected plants included general stunting, small leaves, formation of excessive buds, and aborted seed pods. In the same region, two other diseases, one in sweet pepper (Capsicum annuum) fields and another affecting passion fruit (Passiflora edulis) vines, were also found. Symptoms on sweet pepper plants included unusually dark green leaves, some of which exhibited a rugose symptom with a zigzag pattern to the midvein, and purple vein discoloration. Passion fruit vines exhibited bud proliferation. Collectively, symptoms resembled those commonly attributed to phytoplasmal infections. Total nucleic acid was extracted from veinal tissues of leaves or buds (soybean). A nested PCR assay using primer pair P1/P7 followed by R16F2n/R16R2 (1) was employed for the detection of putative phytoplasmas that might be associated within symptomatic plants. All seven symptomatic plants (three soybean, three sweet pepper, and one passion fruit) tested, but not healthy controls, yielded positive results. Restriction fragment length polymorphism (RFLP) analysis of nested PCR products using restriction enzymes AluI, BfaI, HhaI, MseI, and RsaI indicated that the three diseases were associated with a very similar or identical phytoplasma. RFLP patterns and sequence analysis of cloned 16S rDNAs (GenBank Accession Nos. FJ226068-FJ226073) revealed that the phytoplasma shared less than 97.5% sequence homology with all previously classified phytoplasmas, and, as such, represents a new taxon most closely related to 16SrXII group (1) strains. To our knowledge, this is the first report of a new phytoplasma associated with diseases of soybean, sweet pepper, and passion fruit in Costa Rica. Reference: (1) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998.

First Report of Xylella fastidiosa in Nerium oleander in Costa Rica.

Oleander (Nerium oleander L.) shrubs presenting mottling, leaf tip and margin scorch, short internodes, defoliation, and branch dieback were observed at different localities in the Central Valley in Costa Rica. Severity of the symptoms ranged widely, and most plants showed both diseased and healthy branches. In severe cases, entire sections of the plant were defoliated. Symptoms resembled those described for oleander leaf scorch (OLS) caused by the bacterium Xylella fastidiosa in the United States (3). This bacterium has been reported in coffee and citrus plants in Costa Rica. Sixty plants from five different places were sampled and tested using ELISA (Agdia Inc., Elkhart, IN) against X. fastidiosa. Thirty-five plants showed absorbance mean value of duplicate wells greater than the mean of control wells plus three times the standard deviation, and therefore were considered positive. Thirty-three of the sixty samples were processed for an immunofluorescence assay modified from Carbajal et al. (1) with antibody to X. fastidiosa (Agdia Inc.). Thirteen samples showed fluorescent rod-shaped bacilli with morphology similar to those observed from a pure culture of X. fastidiosa obtained from coffee. Ten of these thirteen samples were positive by ELISA. DNA extracts (2) from three of the oleander plants with high ELISA absorbance values were tested by nested PCR with primer pair 272-1/272-2 followed by the pair 272-1 int/272-2 int (4). Two of the samples were positive for the bacterium and one of the PCR products was cloned and sequenced in both directions (GenBank Accession No. EU009615). The negative (PCR mix) and positive (pure culture of X. fastidiosa isolated from grapevine) controls for nested-PCR were indeed negative and positive, respectively. The BLAST program was used to compare the sequence to the nucleotide collection (nr/nt) and Microbe Assembled Genomes databases in GenBank. All matches corresponded to X. fastidiosa sequences. The sequence showed 97% similarity with strains Found-4 (coffee strain from Brazil) and Found-5 (citrus strain from Brazil) and 96% similarity with strain Ann-1 from oleander in California. On the basis of serological, microscopic, and molecular detection of X. fastidiosa from oleander exhibiting symptoms of OLS similar to those reported in the literature, this pathogen likely is causing the symptoms we observed in Costa Rica. References: (1) D. Carbajal et al. Curr. Microbiol. 49:372, 2004. (2) M. J. Green et al. Plant Dis. 83:482, 1999. (3) Q. Huang et al. Plant Dis. 88:1049, 2004. (4) M. R. Pooler and J. S. Hartung. Curr. Microbiol. 31:377, 1995.

First Report of Xylella fastidiosa in Avocado in Costa Rica.

Since the late 1990s, chlorotic mottling, marginal scorch, deformation of leaves, defoliation, shortening of internodes, and branch dieback have been observed in avocado trees (Persea americana Mill.) in Costa Rica. The symptoms are not uniformly distributed in the tree, so some branches are symptomatic while others are not. These symptoms are similar to several leaf scorch diseases caused by the bacterium Xylella fastidiosa Wells (2,4). This bacterium has been detected in coffee and citrus plants in Costa Rica. Of 227 avocado trees tested by double-antibody sandwich (DAS)-ELISA with X. fastidiosa specific antiserum (Agdia Inc., Elkhart, IN) from 2000-2004, 188 were positive. Results of ELISA tests of individual trees varied with the season and branches tested. Fifteen greenhouse-grown, ELISA-negative avocado seedlings were grafted with budwood from an ELISA-positive tree. Eight of these developed scorch symptoms and one also showed chlorotic mottling and deformation, showing that the disease is graft transmitted. All of these features are characteristic of diseases caused by X. fastidiosa (2,4). Transmission electron microscopy of leaf petioles from three field trees positive by ELISA, revealed rod-shaped bacilli approximately 1.6 to 2.0 µm long and 0.3 µm in diameter with a rippled cell wall inside xylem vessels and embedded in a matrix; morphology and measurements that are consistent with those reported for X. fastidiosa (2). DNA extraction and PCR attempts have been limited by mucilaginous sap from avocado. Positive PCR results (approximately 472-bp band) were obtained from two of the grafted seedlings and seven field trees from two distinct geographical locations (Alajuela and San José provinces) with DNA extractions from the plant sap using DNeasy Plant Mini Kit (Qiagen GmbH, Hilden, Germany) following a modified protocol (1) and nested PCR (3). Four of the PCR products, including one from the grafted seedlings, were cloned and sequenced in duplicate. GenBank sequences EU021997 to EU022000 present 99 to 100% sequence identity to a Pierce's disease strain from California (Temecula1) and 94 to 95% to a citrus variegated chlorosis strain from Brazil (Found-5). Several attempts have been made to isolate the bacterium in 'periwinkle wilt' and buffered cysteine-yeast extract media with negative results, probably because of the rapid production of mucilaginous sap when the avocado tissues were sampled. To our knowledge, this is the first report of X. fastidiosa in avocado trees. References: (1) M. J. Green et al. Plant Dis. 83:482, 1999. (2) S. S. Hearon et al. Can. J. Bot. 58:1986, 1980. (3) M. R. Pooler and J. S. Hartung. Curr. Microbiol. 31:377, 1995. (4) A. H. Purcell et al. Phytopathology 89:53, 1999.

First Report of a Phytoplasma Associated with Witches'-Broom of the Giant Coral Tree (Erythrina poeppigiana, Fabaceae) in Costa Rica.

The giant coral tree (Erythrina poeppigiana, Fabaceae) is a common shade tree in coffee plantations in Costa Rica. Coral trees are pruned to decrease fungal infections and increase nitrogen fixation. Recently, severe shoot proliferation, internodes shortening, and leaf reduction were observed in pruned shade trees in the south of San José Province, Costa Rica. Leaf samples from 10 symptomatic E. poeppigiana trees were collected. Also, two samples from symptomless coral trees were collected from areas free of witches'-broom. Total DNA was extracted from 0.5 g of petiole tissue from all samples with the plant extraction mini kit (Qiagen GmbH, Hilden, Germany) with a modified protocol (2) and assayed by nested PCR with phytoplasma universal rDNA primers (P1/P7) (1) and R16F2n/R16R2 (3). All symptomatic trees tested positive for phytoplasmas by PCR, yielding the expected 1.2-kb band. DNA from the symptomless trees was not amplified by PCR. The restriction fragment length polymorphism analyses (HaeIII, AluI, RsaI, BfaI, HpaII, KpnI, HhaI, and MseI) and the sequence of the 1.2-kb PCR fragment (GenBank Accession No. DQ485305) revealed that the phytoplasma associated with coral tree witches'-broom belongs to the aster yellows phytoplasma group (16SrI) (4). To our knowledge, this is the first report of a phytoplasma belonging to the aster yellow group causing witches'-broom in the Erythrina genus. References: (1) S. Deng and C. Hiruki. J. Microbiol. Methods 14:53, 1991. (2) M. J. Green et al. Plant Dis. 83:482, 1999. (3) D. E. Gundersen and I. M. Lee. Phytopathol. Mediterr. 35:144, 1996. (4) I. M Lee et al. Int. J. Syst. Bacteriol.48:1153, 1998.

First Report of Citrus Blight in Costa Rica.

Citrus blight (CB), causing a chronic decline of citrus, has been an important disease in Florida for over 100 years. CB was first reported in Brazil in the 1980s and is now responsible for the removal of nearly 10% of the trees from production annually. No causal agent has been identified, but CB has been root-graft transmitted to healthy trees, suggesting that the causal agent is infectious (3). Since 1997, CB symptoms were observed in several groves in northern Costa Rica, the most important citrus area of approximately 25,000 ha. Symptoms observed include a general decline and wilt of the tree canopy, off-color leaves, leaf drop, twig dieback, small fruit, delayed blossom, poor growth, and death. A survey near Guanacaste revealed CB symptoms in 7-yr-old Valencia and Pineapple orange trees (Citrus sinensis (L.) Osbeck) grafted on Carrizo citrange (C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.) rootstock. Since 1997, 6% of the trees in this area have been replanted annually because of CB symptoms. Similar situations were observed in other groves in the northern citrus area. Dot immunobinding assays (DIBA) (1) were used to detect the P12 protein associated with CB with 20 of 22 trees showing CB-like symptoms giving a positive test. Zinc (Zn) accumulation in trunk wood and water uptake tests were done according to Roistacher (2) in 8 healthy and 20 symptomatic trees which were positive for CB using DIBA. The average Zn concentration of 16 declining trees was 4.6 ± 1.9, whereas the average concentration for 8 healthy trees was 2.0 ± 0.9. The average water uptake in 1 min was 14 ml for healthy trees, and virtually zero for the 20 symptomatic trees. These diagnostic tests confirm the presence of CB in the northern citrus area of Costa Rica, and the surveys indicate the disease is beginning to spread and become economically important. To our knowledge, this is the first report of CB in commercial citrus in Costa Rica. References: (1) K. S. Derrick et al. Plant Dis. 74:168, 1990. (2) C. N. Roistacher. Pages 57-66 in: Graft-Transmissible Diseases of Citrus. Handbook for Detection and Diagnosis. C.N. Roistacher, ed. Food and Agriculture Organization, Rome, 1991. (3) D. P. H. Tucker et al. Plant Dis. 68:979, 1984.

First Report of Xylella fastidiosa Infecting Citrus in Costa Rica.

Citrus variegated chlorosis (CVC) is an important disease mainly of sweet orange (Citrus sinensis (L.) Osbeck) cultivars. It was first described in Brazil in the state of Sa Paulo in 1987 (4). The disease has spread to all Brazilian states that grow citrus and is affecting more than one-third of the orange trees grown in Brazil. CVC is caused by Xylella fastidiousa, a xylem-limited, gram-negative bacterium. During the last 4 years, symptoms including leaf interveinal chlorosis, stunting, canopy dieback, and hard and undersized fruits, similar to those caused by CVC (3), appeared in sweet orange trees used as shade plants for coffee plantations and as fence posts in Costa Rica. Necrotic lesions on the abaxial side of the leaves as reported in Brazil were rarely observed. Leaf petiole samples from 25 symptomatic sweet orange trees reacted positively with a X fastidiosa-specific antiserum (AGDIA Inc., Elkart, IN) in a double-sandwich antibody enzyme-linked immunosorbent assay (DAS-ELISA). A fastidious, gram-negative bacterium identified as X. fastidiosa using DAS-ELISA was isolated on perwinkle wilt (PW) medium plates (1) from citrus stems showing CVC symptoms, but not from asymptomatic trees. The isolated colonies were circular and opalescent with diameters of 2 to 3 mm and were clearly visible within 6 to 7 days after streaking. Petiole sections from symptomatic plants observed with scanning electron microscopy showed rod-shaped bacteria with rippled cell walls tightly packed in xylem vessels, as described for X. fastidiosa previously (2), and with transmission electron microscopy, the bacteria were morphologically similar to those reported previously for CVC (2). To our knowledge, this is the first report of X. fastidiosa associated with citrus in Costa Rica. References: (1) M. J. Davis et al. Curr. Microbiol. 6:309, 1981. (2) J. S. Hartung et al. Phytopathology 84:591, 1994. (3) R. F. Lee et al. Summa Phytopathol. 19:123, 1993. (4) V. Rossetti et al. 1990, C.R. Acad. Sci. (Paris) 310:345-349.

[Medium and long-term results of the use of videothorascopy in surgery of pulmonary metastasis resection]. / Resultados a medio y largo plazo de la utilización de videotoracoscopia en la cirugía de resección de las metástasis pulmonares.

The surgical resection of pulmonary metastases is a method of treatment accepted as habitual in thoracic surgery. However, it continues to be a source of controversy if this resection must be realised by thoracotomy or by modern video-assisted techniques. With the aim of finding a response to this controversy in our work milieu, a review was made of the surgical interventions carried out in order to resect pulmonary metastases. Between January 1997 and December 2001, 56 patients were found whose pulmonary metastases had been resected by videothorascopy out of a total of 252 metastasectomies (22.2%). The primary tumours were classified in 4 groups: sarcoma (n=11); colorectal (n=25); renal (n=5); and others (n=15). Videothorascopy was carried out on the right hemithorax (n=28), left hemithorax (n=22) or on both at once (n=6). Operational mortality was nil and the only morbidity attributable to the technique was a defect of re-expansion following the removal of the thoracic drainage in one patient. Using the Kaplan-Meier method, the probability of survival in this series of patients was 60.4% after 5 years, with an average survival time of 48 months. All of this data supports the use of videothorascopy in our milieu on patients with pulmonary metastases. However, in the light of the results, it is important in using this technique to place special emphasis on obtaining good margins of resection, due to the real risk of local recurrence on these margins in the medium term.

Resultados a medio y largo plazo de la utilización de videotoracoscopia en la cirugía de resección de las metástasis pulmonares / Medium and long-term results of the use of videothorascopy in surgery of pulmonary metastasis resection

La resección quirúrgica de las metástasis pulmonares es un método de tratamiento aceptado como habitual en la cirugía torácica. Sin embargo, continúa siendo un motivo de controversia si esta resección se debe realizar por toracotomía, o por las modernas técnicas vídeo asistidas. Con la finalidad de buscar una respuesta a dicha controversia en nuestro medio de trabajo, se efectuó una revisión de las intervenciones quirúrgicas realizadas con el objetivo de resecar metástasis pulmonares. Entre enero de 1997 y diciembre de 2001, se encontraron 56 pacientes a quienes se había resecado metástasis pulmonares por videotoracoscopia de entre un total de 252 metastasectomías (22,2%). Se clasificaron los tumores primarios en 4 grupos: sarcoma (n=11); colorrectal (n=25); renales (n=5); y otros (n=15). La videotoracoscopia se realizó en el hemitórax derecho (n=28), hemitórax izquierdo (n=22) o en ambos a la vez (n=6). La mortalidad operatoria fue nula y la única morbilidad atribuible a la técnica fue un defecto de reexpansión tras la retirada del drenaje torácico en un paciente. Utilizando el método de Kaplan-Meier, la probabilidad de supervivencia de esta serie de pacientes fue del 60,4% a los 5 años, con tiempo de supervivencia medio de 48 meses. Todos estos datos apoyan en nuestro medio el empleo de videotoracoscopia en pacientes con metástasis pulmonares. Sin embargo, y a la vista de los resultados, es importante al efectuar esta técnica poner un cuidado especial en conseguir buenos márgenes de resección, debido al riesgo real de recurrencia local sobre dichos márgenes a medio plazo

The surgical resection of pulmonary metastases is a method of treatment accepted as habitual in thoracic surgery. However, it continues to be a source of controversy if this resection must be realised by thoracotomy or by modern video-assisted techniques. With the aim of finding a response to this controversy in our work milieu, a review was made of the surgical interventions carried out in order to resect pulmonary metastases. Between January 1997 and December 2001, 56 patients were found whose pulmonary metastases had been resected by videothorascopy out of a total of 252 metastasectomies (22.2%). The primary tumours were classified in 4 groups: sarcoma (n=11); colorectal (n=25); renal (n=5); and others (n=15). Videothoroscopy was carried out on the right hemithorax (n=28), left hemithorax (n=22) or on both at once (n=6). Operational mortality was nil and the only morbidity attributable to the technique was a defect of re-expansion following the removal of the thoracic drainage in one patient. Using the Kaplan-Meier method, the probability of survival in this series of patients was 60.4% after 5 years, with an average survival time of 48 months. All of this data supports the use of videothorascopy in our milieu on patients with pulmonary metastases. However, in the light of the results, it is important in using this technique to place special emphasis on obtaining good margins of resection, due to the real risk of local recurrence on these margins in the medium term

First Report of an Aster Yellows Subgroup 16SrI-B Phytoplasma Infecting Chayote in Costa Rica.

An outbreak of a witches' broom disease affected approximately 20% of plants in several chayote (Sechium edule (Jacq.) Schwartz) fields in the commercial production area of the Ujarrás Valley, Cartago Province, Costa Rica during 2000 and 2001. Affected chayote plants exhibited symptoms, including basal proliferation with severe foliage reduction, aborted flowers, and deformed fruits, suggestive of phytoplasmal infection. Two other symptomatic cucurbit species growing near the chayote fields were also identified. These species were tacaco plants (S. tacaco (Pitt.) C. Jeffrey), an edible cucurbit for domestic marketing in Costa Rica, showing severe size reduction of leaves and fruits, and Rytidostylis carthaginensis (Jacq.) Kuntze, a weed in chayote and tacaco fields, exhibiting abnormal tendril proliferation. Plants were analyzed for phytoplasma infection by a nested polymerase chain reaction (PCR) assay, using the universal rRNA primer pair P1/P7 followed by R16F2n/R16R2 (2). Phytoplasmas were detected in all symptomatic samples (18 chayote, 6 tacaco, and 3 weed) tested but were undetectable in all asymptomatic samples (10 chayote, 6 tacaco, and 2 weed). Restriction fragment length polymorphism (RFLP) analysis of PCR products (16S rDNA sequences) by separate digestion with eight restriction enzymes (RsaI, HhaI, KpnI, BfaI, HaeIII, HpaII, AluI, MseI) revealed that a phytoplasma belonging to subgroup 16SrI-B in the aster yellows phytoplasma group (16SrI) was associated with chayote witches' broom (CWB). The same or very similar phytoplasmas were found in both symptomatic tacaco and R. carthaginensis plants. Phylogenetic analysis of 16SrDNA sequences also confirmed the CWB phytoplasma to be most similar to members of subgroup 16SrI-B. Similar diseases in chayote and other cucurbits have been reported in Brazil (3), Taiwan (1), and Mexico (4). The CWB phytoplasma differs from the phytoplasma (16SrIII-J subgroup) associated with chayote in Brazil. The identities of phytoplasmas associated with cucurbits in Taiwan and Mexico are unknown. The occurrence of an aster yellows group phytoplasma in chayote may pose a potential threat to continued production and exportation of this cash crop. To our knowledge, this is the first report of 16SrI-B subgroup phytoplasmas in naturally infected cucurbits in Costa Rica. References: (1) T. G. Chou et al. Plant Dis. Rep. 60:378, 1976. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) H. G. Montano et al. Plant Dis. 84:429, 2000. (4) E. Olivas. Rev. Fitopatol. (Lima) 13:14, 1978.

Occurrence of Coffee ringspot virus, a Brevipalpus Miteborne Virus in Coffee in Costa Rica.

Coffee ringspot virus (CoRSV) (family Rhabdoviridae) is transmitted by Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae). Coffee ringspot disease was first reported in coffee plants from Brazil in 1939 (1). In August 2000, severe symptoms of concentric ringspots and "oak leaf" patterns on coffee leaves (Coffea arabica L. cv. Catuai) were observed during field inspections conducted in two areas of San Gabriel de Desamparados, Costa Rica. The disease caused premature fruit and leaf drop in the affected plants. Some areas within the ringspot lesions remained green on senescent leaves. Because CoRSV particles remain restricted to lesion areas (1), this virus has not been purified, and antiserum for virus detection is not available. Therefore, leaves with symptoms were collected and examined by transmission electron microscopy. In ultrathin sections of symptomatic leaves, arrays of rhabdovirus-like particles were associated with the nucleus as described for CoRSV (2). Healthy tissues did not contain similar arrays of bacilliform and bullet-shaped particles. Twenty mites collected from the infected plants at the same locations and time were slide-mounted and identified as B. phoenicis. High populations of this mite were also observed infesting plants of Cajanus cajan L. that were intercropped with coffee at the same location. Sweet orange trees growing in the same fields as shade for the coffee did not show symptoms of citrus leprosis, a disease caused by another Brevipalpus-transmitted virus that was recently reported in Panama (3). To our knowledge, this is the first report of a virus similar to CoRSV in Costa Rica. The spread of this virus, presumably CoRSV, could seriously affect the coffee industry throughout Central America by increasing production costs. It may be necessary to apply one or more foliar acaricides to effectively control the mite vector. References: (1) A. Bitancourt. O. Biol. 5:33, 1939. (2) C. M. Chagas et al. Phytopathol. Z. 102:100, 1981. (3) F. S. Dominguez et al. Plant Dis. 85:228, 2001.

First Report of Sugarcane yellow leaf virus (ScYLV) in Costa Rica.

In Costa Rica, sugarcane plants with symptoms similar to those described for yellow leaf syndrome (YLS) (1,2) were first observed in 1994 in research plots of imported material in the midland areas of San Carlos and Turrialba. Recently, the same symptoms have been observed in commercial plantations in Turrialba. Symptomatic plants were characterized by yellowing of the leaves and central veins, the yellowing being more intense near the leaf tips. In severe cases, veins became reddish, and necrosis developed along the leaf edges, beginning at the leaf tip and extending to the base of the leaf. Growth of stems and roots was also reduced in infected plants. Minipurifications of six plants of four different varieties were examined by immunospecific electron microscopy (ISEM) using polyclonal antibodies (1). They were: one symptomatic plant each of the varieties H782313 and H608521; two symptomatic plants of H657052, and one asymptomatic plant each of H608521 and H827318. Isometric particles of approximately 28 nm were observed in the asymptomatic H827318 plant and in all symptomatic plants, with the exception of one plant of H657052. The size and morphology of the particles was similar to those reported for Sugarcane yellow leaf virus (ScYLV) (2). The presence of ScYLV was verified by indirect enzyme-linked immunosorbent assay (ELISA) using polyclonal antibodies (1). Twenty-two of 24 symptomatic plants and five of 13 asymptomatic plants were positive for ScYLV. These findings confirm the association of ScYLV with the yellows syndrome of sugarcane observed in Costa Rica. However, as was also reported by Scaglusi and Lockhart (1), ScYLV was not detected in several symptomatic plants, and research is continuing to determine whether other pathogens are associated with this syndrome in Costa Rica. References: (1) S. Scagliusi and B. E. L. Lockhart. Phytopathology 90:120, 2000; (2) J. Vega et al. Plant Dis. 81:21, 1997.

First Report of Xylella fastidiosa Infecting Coffee in Costa Rica.

In 1995, severe symptoms were observed on 'Caturra' and 'Catuaí' coffee (Coffea arabica L.) varieties in farms in the southern part of the Central Valley in Costa Rica. Symptoms were reduced leaf size, malformation of leaves, curling of leaf edges, shortening of internodes, and severe leaf chlorotic mosaic, which sometimes became necrotic. Abortion of flowers and young beans was also observed, with a reduction in yield. Plants also showed irregular growth with an atypical curling appearance that gave rise to the Spanish name "crespera." Ten and three healthy plants were inoculated by grafting in the greenhouse, using infected and healthy budwoods, respectively. Approximately 6 months after inoculation, 3 of 10 grafted plants with infected budwoods showed symptoms of leaf chlorosis, curling, and malformation of leaves and bunched new flushes. Samples of 39 symptomatic plants collected from the field and samples of 3 healthy plants maintained in the greenhouse were tested by enzyme-linked immunosorbent assay (ELISA). All (100%) analyzed symptomatic samples were positive for X. fastidiosa, and all healthy controls were negative. The symptoms observed in Costa Rica are different from those described for coffee leaf scorch in Brazil (1,2), but the climatological conditions and soil type present in Costa Rica are also very different from the areas where X. fastidiosa occurs in Brazil. Leafhoppers were collected randomly in one of the most affected regions. Graphocephala permagna and Erythrogonia sonora were the most frequent insect species found associated with coffee. In ELISA, 34.5% (10 of 29) and 23.8% (5 of 21) of the collected specimens belonging to G. permagna and E. sonora, respectively, tested positive for X. fastidiosa. These positive ELISAs do not necessarily mean that the insect is a vector. The results presented here extend the known geographic distribution of X. fastidiosa. To our knowledge, this is the first report of X. fastidiosa in coffee in Costa Rica. References: (1) M. J. G. Beretta et al. Plant Dis. 80:821, 1996. (2) de Lima et al. Plant Dis. 82:94, 1998.

First Report of the Cymbidium Mosaic Potexvirus (CymMV) Infecting the Terrestrial Orchid Phaius tankervilliae in Costa Rica.

In 1996, plants of the terrestrial orchid Phaius tankervilliae from a nursery in the Central Valley of Costa Rica were observed with mild to severe foliar symptoms of chlorotic streak. No differences were observed in growth, bulb production, flowers, or flowering time between symptomatic and asymptomatic plants, except the symptomatic plants had earlier senescence. Occasionally, the flowers displayed symptoms of chlorosis and white rings in the sepals. Extracts from symptomatic leaves were concentrated by differential centrifugation and analyzed after sucrose gradients. Negative staining of fractions from gradients from symptomatic plants showed the presence of filamentous viral particles 500 by 17 nm. Purified particles contained a single major protein of about 28 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and a single RNA of about 7 kb, which is greater than the 6.2 kb reported (GenBank). These data suggest the presence of a potexvirus in symptomatic plants (1,2). In enzyme-linked immunosorbent assays, symptomatic plants reacted strongly with antiserum specific for Cymbidium mosaic potexvirus (CymMV). This is the first report of CymMV in P. tankervilliae in Costa Rica. References: (1) J. A. Frowd and J. H. Tremaine. Phytopathology 67:43, 1977. (2) H. T. Hsu et al. Phytopathology 82:491, 1992.

Occurence of citrus viroids in Costa Rica

A survey for citrus viroids was conducted in the major citrus commercial growing areas in Costa Rica. Screening of 36 sweet orange and 12 lemon trees resulted in the detection of members of four of the five citrus viroid groups as determined by nucleic acid hybridization using specific RNA probes and polymerase chain reaction (PCR) using specific oligonucleotide primers. CEVd, CVd-IIa, CVD-IIb and CVd-III viroids were found to be widespread in the three main regions of commercial citrus production. CVd-Ib was only found in lemon in Nicoya

Chayote Mosaic, a New Disease in Sechium edule Caused by a Tymovirus.

A sap-transmissible virus was isolated from chayote (Sechium edule) in Costa Rica. Infected plants showed chlorotic spots and rings, and blotchy mosaics, which often coalesced to give a complete mosaic and leaf deformation. By electron microscopy, spherical virus-like particles of approximately 29 nm in diameter were visible, and cytological changes associated with the chloroplasts were observed. The virus particles sedimented in sucrose density gradients as two components, a top component of empty protein shells and a bottom component of electron-dense particles. Electrophoretic analysis showed a single-stranded RNA of approximately 5.7 kb and capsid protein (CP) subunits of ∼22 kDa. The virus was identified as a member of the tymovirus group on the basis of particle morphology, size, sedimentation in sucrose gradients, cytopathological effects, and capsid protein and genome properties, and it was tentatively named chayote mosaic virus (ChMV).

Occurrence of citrus viroids in Costa Rica.

A survey for citrus viroids was conducted in the major citrus commercial growing areas in Costa Rica. Screening of 36 sweet orange and 12 lemon trees resulted in the detection of members of four of the five citrus viroid groups as determined by nucleic acid hybridization using specific RNA probes and polymerase chain reaction (PCR) using specific oligonucleotide primers. CEVd, CVd-IIa, CVD-IIb and CVd-III viroids were found to be widespread in the three main regions of commercial citrus production. CVd-Ib was only found in lemon in Nicoya.