bluuebunny/crossref_metadata_2025 huggingface dataset:
First Report of Armillaria gallica Causing Armillaria Root Rot in Daylily in South Carolina
Authors: Schnabel G. , Bussey K. E. , Bryson P. K.
Published: May 2007

Daylily (Hemerocallis sp.) plants declined in a homeowner's backyard in Walhalla, SC in June 2004. The backyard in northwestern South Carolina contained multiple, hardwood tree stumps, was surrounded by mature hardwood trees, and contained a dogwood tree showing symptoms of Armillaria root rot. Daylily plants were stunted and necrosis of leaves began at the leaf tips. A cross section through the crown of the wilting plants revealed necrotic areas with the presence of white mycelial fans. Rhizomorphs were found in the direct vicinity of the daylily root system, on the roots of the dogwood, and throughout surrounding soil. Diseased daylily crowns, rhizomorphs, and dogwood bark containing mycelial fans were collected. Small sections of white mycelial fans from daylily crowns and the dogwood sample were transferred to benomyl dichloran streptomycin (BDS) selective medium. Rhizomorph pieces were surface sterilized in a 0.6% sodium hypochlorite solution for 10 min and rinsed with sterile water before being transferred to BDS selective medium. Fungal cultures from all three sources looked similar on BDS medium and developed mainly crustose mycelium with some parts being aerial. After 1 week of incubation at room temperature in the dark, all cultures developed nonmelanized, mycelial fans that initiated from the center of the colony. The nucleotide sequences of internal transcribed spacer regions 1 and 2 and the intergenic spacer region 1 were identical for all isolates, and a BLAST search in GenBank of these sequences confirmed the identity of the pathogen as A. gallica (Marxmueller & Romagnesi) for both loci. To our knowledge, this is the first report of A. gallica causing disease on Hemerocallis spp. Our findings indicate that daylilies might be at risk for infection and should not be cultivated in soils containing rhizomorphs from pathogenic Armillaria species.
First Report of Phoma exigua as a Pathogen of Salal (Gaultheria shallon) in British Columbia, Canada
Authors: Shamoun S. F. , Zhao S.
Published: May 2007

Salal (Gaultheria shallon Pursh.) is an ericaceous, evergreen, and rhizomatous shrub that competes for nutrients and moisture with young conifers in low elevation, coastal British Columbia (BC). A survey was conducted on southern Vancouver Island, BC during the summer of 1999 to find fungal pathogens of salal that might serve as biocontrol organisms (3). Phoma exigua Desmaz. (isolate PFC2705) near Parksville, BC proved to be pathogenic on salal. Identification of PFC2705 at the Centraalbureau voor Schimmelcultures was based on morphology and ITS sequences (GenBank Accession No. AY927784). Pathogenicity was determined with 24 salal seedlings (3-month-old) by inoculating with mycelial suspensions (20% v/v) or conidial suspensions (1 × 106 conidia per ml in 0.5% potato dextrose broth). Inoculated seedlings were placed in plastic bags and incubated in a greenhouse (16 to 23°C with natural light). Plastic bags were removed after 2 days. Initial disease symptoms were observed 2 days after inoculation. Brown, sunken lesions appeared on the surface of young leaves and stems and extended quickly. All seedlings were killed within 14 days. Twelve control plants showed no disease symptoms. With diseased salal leaves incubated at 23°C with 12-h fluorescent light/dark and 100% relative humidity, pycnidia appeared on leaf surfaces within 5 days. Conidia were hyaline, ellipsoid, one-celled, sometimes two- to three-celled, 2.5 to 3.8 × 5 to 12.5 μm, with a rounded base; the colony was gray or dark gray on potato dextrose agar after 5 to 7 days. Reisolation from the inoculated diseased leaves produced a mycelial colony that shared the same growth and morphological characteristics as the initial isolate. Phyllosticta gaultheriae Ellis & Everh., a widely reported foliar pathogen of salal, is distinct morphologically from P. exigua (1). To our knowledge, this is the first report of P. exigua as a pathogen of salal in Canada (2). A voucher specimen has been deposited at the Pacific Forestry Center Herbarium (DAVFP No. 28735).

References: (1) J. Bissett and S. J. Darbyshire. No. 275 in: Fungi Canadenses, 1984. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society. St. Paul. MN, 1989. (3) S. F. Shamoun et al. Can. J. Plant Pathol. 22:192, 2000.
First Report of Rhizoctonia solani AG-4 and AG-2-2 on Lupinus angustifolius in Canada
Authors: Chang K. F. , Hwang S. F. , Gossen B. D. , Howard R. J. , Lopetinsky K. , Olson M.
Published: May 2007

Narrow-leaved lupine (Lupinus angustifolius L.) is grown as a grain legume crop in Australia and Europe where it is used as feedstock in the livestock and aquaculture industries. During July 2003, a stem rot disease was observed in narrow-leaved lupine (cv. Arabella) plants in a research plot at the Crop Diversification Centre North (CDCN), Edmonton, Alberta, Canada. The disease was also found on cv. Rose at the CDCN and cv. Arabella in experimental fields near Devon, Ellerslie, and Westlock, Alberta during the late spring of 2004. Diseased plants showed dark brown-to-black stems with sunken and constricted lesions at the soil level. Young leaves became shrunken and twisted and seedlings collapsed. Rhizoctonia solani was consistently isolated from lesions on taproots and basal stems of diseased plants. Colonies of cream-colored mycelia grew close to the surface of potato dextrose agar (PDA). Most sclerotia formed inside the medium. Agar disks (1 cm in diameter) of isolates LP-11Bb, LP-24C, and LP-25C were attached to the opposite sides of basal stems (180° apart) of 1-month-old lupine seedlings (cv. Arabella). Inoculated plants were incubated for 2 days in black plastic bags under a greenhouse bench at approximately 20°C. All isolates caused brown lesions on the lower stems (extending up to 7 cm above ground level), girdling, and root rot. Plants wilted within 7 to 10 days after inoculation, and aerial mycelia appeared on the basal stems. R. solani was reisolated from the infected crown tissues using PDA to complete Koch's postulates. The isolates were paired with AG tester strains of R. solani. Isolates LP-11Bb and LP-24C were identified as AG-4 while isolate LP-25C was identified as AG-2-2. In another trial, eight isolates of R. solani (unknown AG types) were tested for virulence on L. angustifolius cv. Arabella using the inoculation method described above. All isolates were pathogenic, and disease severity that was based on a 0 to 4 scale ranged from 2.7 to 3.2. The most virulent strain was LP-24C, which caused a 77% loss in fresh weight compared with the noninoculated control plants. R. solani AG-8 is associated with Rhizoctonia disease of lupine in Australia (1) and also causes bare patch disease of wheat. To our knowledge, this is the first report of R. solani on lupine in Canada. This disease could have a significant impact on the commercial production of lupine in Alberta.

Reference: (1) M. W. Sweetingham et al. Pages 466–486 in: Advances in Lupin Disease Management in Australia. Proc. Int. Lupin Conf., 8th. G. D. Hill, ed. International Lupin Association, Canterbury, New Zealand, 1999.
First Report of Fusarium oxysporum f. sp. canariensis Causing Fusarium Wilt on Phoenix canariensis in Sardinia, Italy
Authors: Migheli Q. , Balmas V. , Muresu M. , Otgianu L. , Fresu B.
Published: May 2007

During the summer of 2004, severe symptoms of wilt were observed on 25-year-old plants of Canary Island Date Palm (Phoenix canariensis Hort. ex Chabaud) located at the seafront of Poetto Beach in the metropolitan area of Cagliari, southern Sardinia, Italy. Symptoms consisted of one-sided leaflet dieback of fronds, necrotic and brown streaking on the lower rachis base of older leaves, and necrosis of vascular bundles. Of 300 palms, there were 90 plants that were symptomatic and at least 4 were dead. Fusarium oxysporum Schlecht. emend. Snyder & Hansen has been consistently isolated from surface-sterilized petioles of symptomatic leaves sampled from affected palms. The opportunistic pathogen Gliocladium vermoesenii (Biourge) Thom was frequently associated with F. oxysporum in diseased samples, confirming previous reports of a disease complex between these two fungi (1). Five F. oxysporum isolates collected from different symptomatic plants were analyzed with a polymerase chain reaction (PCR)-based assay with the F. oxysporum f. sp. canariensis-specific primers HK66 + HK67 (2). The thermocycling schedule was as follows: initial denaturation at 94°C for 5 min, 35 cycles each of 1 min at 94°C, 1 min at 62°C, 1 min and 30 s at 72°C, followed by a final extension at 72°C for 5 min. A 567-bp PCR product of the expected size was obtained from all tested F. oxysporum isolates, allowing their identification as F. oxysporum f. sp. canariensis. This disease was previously reported from other Italian regions (Sicily, Marche, and Liguria), but its presence in Sardinia should be considered carefully since it represents a serious threat to ornamental palms, which are abundant all over the island. The source of this outbreak may be related to the importation of seedlings from areas where F. oxysporum f. sp. canariensis is widely established.

References: (1) H. D. Ohr. Pink rot (Gliocladium Blight). Pages 24–25 in: Diseases and Disorders of Ornamental Palms. A. R. Chase and T. K. Broschat, eds. The American Phytopathological Society, St. Paul, MN, 1991. (2) T. R. Plyler et al. Phytopathology 89:407, 1999.
First Report of Bean pod mottle virus in Soybean in Iran
Authors: Shahraeen N. , Ghotbi T. , Salati M. , Sahandi A.
Published: May 2007

Soybean (Glycine max (L.) Merr.) has been increasing in importance and acreage for the past 5 years in Iran and is now planted on approximately 108,000 ha. Previous surveys in Iran of viruses infecting soybean failed to identify Bean pod mottle virus (BPMV), but the incidence of other common viruses of soybean in the field has been reported (1). During October 2004, symptoms characteristic of those caused by BPMV including mosaic, puckering of trifoliate leaves, and delayed maturity of stems or green stems were observed in soybean fields in the Takhti Mahaleh, Versen, and Hashemabad areas located in the Gorgan Province. Sporadic incidence of plants infected with BPMV has been usually of minor importance to growers. Symptoms were often overlooked or considered to be physiological disorders. A visual assessment was made to determine incidence of green stem in the commonly grown soybean cv. Sahar. Forty soybean plants showing symptoms of crinkling, mottling, green stem, and retaining green leaves were sampled by collecting one trifoliate leaf near the top of the plant. All samples were tested in parallel for BPMV using double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). BPMV was detected in 40% of the samples. Seven of the samples shown to be infected with BPMV using DAS-ELISA were mechanically (2) transferred to soybean seedlings in the greenhouse. These plants developed systemic mottle symptoms typical of those caused by BPMV and tested positive for BPMV using DAS-ELISA. The distribution of BPMV within soybean-growing regions, exploration of potential virus reservoirs, and economic impact of this virus have yet to be determined. There is no published report on the presence of potential BPMV vectors including the bean leaf beetle (Cerotoma trifurcata) from soybean fields in Iran. To our knowledge, this is the first report of BPMV in Iran.

References: (1) A. R. Golnaraghi et al. Plant Dis.88:1069, 2004. (2) R. Louie et al. Plant Dis.84:1133, 2000.
First Report of Powdery Mildew Caused by Leveillula taurica on Tomato and Pepper in Bolivia
Authors: Correll J. C. , Villarroel M. I. , McLeod P. J. , Cazon M. I. , Rivadeneria C.
Published: May 2007

Chlorotic and necrotic lesions typical of powdery mildew caused by L. taurica were observed in several tomato (Lycopersicon esculentum) and pepper (Capsicum annuum) fields in Santa Cruz State, Bolivia near the town of Mairana during September 2004. The tomato cultivars affected were Santa Clara, Superman, and Cool 45. Symptoms included bright yellow chlorotic lesions or brown necrotic lesions on different age leaves. Examination of samples collected from several fields revealed sporulation of L. taurica on abaxial leaf surfaces. The fungus had branched conidiophores, a tapered or pyriform apical conidium, with other conidia being more cylindrical (1,2). Conidial size was approximately 60 × 18 μm. Only the Oidiopsis stage was observed. Disease severity was high and caused a significant amount of leaf necrosis and partial defoliation on tomato. Only sporadic lesions were observed on pepper cv. YoloWonder and no significant foliar damage was observed. The growing region receives approximately 75 mm of rainfall annually with most of the rainfall occurring between October and April. Thus, powdery mildew was observed near the end of the normal 5-month dry season. It is likely that the disease has been in the region for some time based on observations from field personnel. Although reported from several other South American countries, to our knowledge, this is the first report of this disease in Bolivia.

References: (1) H. J. Boesewinkel. Bot. Rev. 46:167, 1980; (2) J. C. Correll et al. Plant Dis. 71:248, 1987.
Verticillium Wilt Incited by Verticillium dahliae in Eggplant Grafted on Solanum torvum in Italy
Authors: Garibaldi A. , Minuto A. , Gullino M. L.
Published: May 2007

Eggplant cultivars grafted on rootstocks resistant to root-knot nematodes (Meloidogyne spp.) are increasingly grown in Italy to reduce nematode infection. During the winter of 2003-2004, eggplants (cv Black Bell and Mirabell) grafted on the nematode-resistant rootstock Solanum torvum were observed with symptoms of a wilt disease in several greenhouses in Sicily (southern Italy). The vascular tissue in stems of affected plants appeared brown. These plants were stunted and developed yellow leaves with brown or black streaks in the vascular tissue. The wilt appeared in several greenhouses at a very low incidence (0.01 to 0.05%). Later, during the fall of 2004, disease incidence was approximately ten times greater in the same greenhouses on new crops. Verticillium dahliae was consistently and readily isolated from symptomatic vascular tissue of the rootstock (S. torvum) and the scion (cv Black bell) when cultured on potato dextrose agar (PDA) (1). Healthy, 50-day-old plants of S. torvum and eggplant (cv. Black Bell) were separately inoculated by root dip with a conidial suspension (1 × 107 CFU/ml) of two isolates of V. dahliae obtained from the rootstock and the scion of the infected grafted plants and with a known pathogenic isolate of V. dahliae from nongrafted eggplant. Noninoculated S. torvum and eggplant served as control treatments. Plants (30 per treatment) were grown in a glasshouse at temperatures ranging between 12 and 41°C (weekly average 15 to 36°C) and relative humidity ranging between 36 and 99% (weekly average 54 to 95%). The first wilt symptoms and vascular discoloration in the roots, crowns, and veins developed 26 and 21 days after inoculation on S. torvum and eggplant, respectively. Seventy-two days after inoculation, 20, 26, and 27% of S. torvum plants and 97, 100, and 87% of the eggplants showed symptoms caused by V. dahliae isolates obtained from the scion of diseased grafted plants, the rootstock of diseased grafted plants, and nongrafted eggplants, respectively. Noninoculated plants remained healthy. To our knowledge, this is the first report in Italy of Verticillium wilt on eggplant grafted on S. torvum rootstocks under commercial conditions. Use of eggplant grafted on the nematode-resistant rootstock of S. torvum presents an interesting opportunity to control the root-knot nematode but has to be carefully considered when dealing with soils severely infested by V. dahliae.

Reference: (1) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002.
First Report of Sapwood Rot of Peach Caused by Schizophyllum commune in China
Authors: Dai Y. C.
Published: May 2007

Peach,Prunus persica (L.) Batsch, is widely cultivated in gardens and plantations in northern China. During the summer of 2002, a severe sapwood rot of 5-year-old saplings was observed in a commercial nursery near Tieling, Liaoning Province, northeast China, 42°24′N, 123°55′E. More than 80% of saplings were infected and 35% were dead. Leaves were chlorotic or necrotic and dry, and wood discoloration and white sapwood rot were observed in cross sections of infected trees. Basidiocarps on the diseased trees were identified as Schizophyllum commune Fr.:Fr. (2); on potato dextrose agar (PDA), isolates obtained from decayed wood yielded colonies characteristic of S. commune as well (3). Basidiocarps had been initiated in early June and sometimes fruited over the entire length of the stem and some parts of major branches. Liaoning Province had an abnormally cold winter in 2001 and freeze injury may have predisposed the saplings to S. commune. In addition to P. persica, P. pseudocerasus Lindl. and P. salicina Lindl. were symptomatic. Pathogenicity was confirmed by inoculation of healthy saplings of peach in the greenhouse. Saplings were subjected to freezing for 1 week and 15 were inoculated with S. commune and five were inoculated with agar. Mycelial plugs, grown for 9 days on PDA, were the inoculum for stem wounds. The inoculated area was then covered by wet cotton and wrapped in Parafilm for 2 weeks. Symptoms developed on 14 of 15 inoculated saplings after 6 weeks. Symptoms progressed from chlorotic leaves to decayed bark and wood. After 10 weeks, 11 saplings were dead. The pathogen was reisolated from 13 of 14 symptomatic saplings, and fruiting bodies of S. commune developed on eight saplings. Control saplings remained symptomless. In China and the United States, S. commune is widely reported as a saprotroph or opportunistic pathogen of many woody angiosperms (4) and some gymnosperms (1). To our knowledge, this is the first report of S. commune causing sapwood rot of P. persica in China.

References: (1) D. F. Farr et al. Fungal Databases, Systematic Botany and Mycology Laboratory. On-line publication. ARS, USDA, 2005. (2) J. P. Lindsey et al. Bibl. Mycol. 63:1, 1978. (3) M. K. Nobles. Can. J. Res. Sect. C Bot. Sci. 26:281, 1948. (4) F. L. Tai. Sylloge Fungorum Sinicorum. Science Press, Beijing, 1979.
A New Technique to Select Mild Strains of Cucumber mosaic virus
Authors: Kobori Takashi , Ryang Bo-Song , Natsuaki Tomohide , Kosaka Yoshitaka
Published: May 2007

An efficient technique to select a good attenuated virus to control Cucumber mosaic virus (CMV) disease was developed. Preliminary screenings were conducted to assess the virulence of virus recovered from dark-green islands and yellow tissues of mosaic leaves of Nicotiana rustica after co-inoculation with an attenuated mutant P2bR46C of CMV and its original severe isolate Pepo. All single-lesion isolates (SLIs) obtained from dark-green islands had the attenuated P2bR46C phenotype, but the SLIs from yellow tissue had either the virulent Pepo or the P2bR46C phenotype. When Pepo-infected N. rustica and tomato plants were grown at 15 or 36°C for 30 days, 17 of 288 SLIs obtained from the treated leaves elicited mosaic and dark-green spots without malformation. Dark-green tissue from each plant infected with 1 of these 17 SLIs then was used to inoculate one plant of N. rustica. All 17 plants had either very mild mosaic or no visible symptoms. One of these potential mild strains, 36R37, had an amino acid substitution on the 2b gene encoding the 2b protein. Isolate 36R37 also was highly cross-protective, and its symptom attenuation was stable for three serial host passages. After cold or heat treatment, the dark-green tissue proved to be a good source for isolating mild strains of the virus.
Six Races of Venturia inaequalis are Found Causing Apple Scab in Spain
Authors: Martínez-Bilbao A. , Murillo J.
Published: May 2007

Apple scab, caused by the ascomycete Venturia inaequalis, is an important disease of apple (Malus domestica) worldwide and is generally managed with intensive applications of fungicides or, for specific markets, by planting of resistant cultivars. Currently, eight races of the pathogen have been defined on the basis of their ability to overcome sources of resistance used by plant breeders (2). We undertook the identification of apple scab races present in Spain as a necessary step for the deployment of resistant cultivars. Spore suspensions (2.5 × 105 spores per ml) were prepared from fresh lesions of apple scab collected from apple trees in commercial or domestic orchards located in the northeastern Spanish provinces of Gerona, Guipúzcoa, and Navarra. To identify races 1 to 7, the suspensions were used to inoculate cv. Gala and six differential apple clones with five replicates. Cultivar Gala was used as a universal susceptible control. The differential apple clones included X2250, X2253 (Geneva), X2249, X2225, X2596 (Prima), and X6518 (M. floribunda 821) (1,4). All leaves were assessed on each inoculated shoot 17 days after inoculation, and the type of symptoms were scored using the scale of Chevalier et al. (3). Sporulation was evaluated on seven replicate leaf discs (1 cm in diameter) for each combination of inoculum and plant host (4). All the inocula tested produced typical apple scab symptoms and sporulation (>106 conidia per cm2) on cv. Gala. Races 2, 3, 5, and 6 were identified on the basis of the elicitation of typical disease symptoms with abundant sporulation (>3 × 106 conidia per cm2) on clones X2250, X2253, X2225, and X2596, respectively. Races 2 and 6 were present in inocula from Gerona, Guipúzcoa, and Navarra, whereas races 3 and 5 were identified only in an inoculum from Tudela, Navarra. An inoculum from La Tallada, Gerona, was assigned to race 1 because it produced typical disease symptoms and sporulation only on cv. Gala, while the differential clones were scored as resistant. In Santesteban, Navarra, a monosporic isolate of V. inaequalis, designated VIP28, was obtained in the field from a single lesion in a 2-year-old tree of clone 2.1.1, which is resistant to race 1. VIP28 produced lesions typical of weak virulence in clone X6518 and produced a significant degree of sporulation (0.8 × 106 conidia per cm2), whereas the differential clones for races 2 to 6 were scored as resistant, indicating that this isolate can be classified as race 7 (1). To our knowledge, this is the first report of races of V. inaequalis present in Spain.

References: (1) G. Bénaouf and L. Parisi. Phytopathology 90:236, 2000. (2) V. G. M. Bus et al. New Phytol. doi:10.1111/j.1469-8137.2005.01395.x, 2005. (3) M. Chevalier et al. Plant Pathol. 40:249, 1991. (4) L. Parisi et al. Phytopathology 83:533, 1993.
First Report of Tobacco as a Natural Host of Tomato yellow leaf curl virus in Spain
Authors: Font M. I. , Córdoba C. , García A. , Santiago R. , Jordá C.
Published: May 2007

Two begomovirus species, Tomato yellow leaf curl Sardinia virus (TYLCSV) and Tomato yellow leaf curl virus (TYLCV), have been identified as causal agents of tomato yellow leaf curl disease (TYLCD) in Spain. TYLCSV was reported in Spain in 1992 and TYLCV in 1997 on tomato crops (3). TYLCV was also reported in common bean (Phaseolus vulgaris L.) and pepper (Capsicum annuum L.) crops in southern Spain in 1997 and 1999, respectively. During the summer of 2004, symptoms of yellowing, crumpling, and necrosis of new leaves were observed sporadically in young, field-grown tobacco (Nicotiana tabacum L.) plants in the Badajoz Province. These tobacco plants were next to tomato crops where TYLCV was detected for the first time in Badajoz in 2003. In September 2004, four symptomatic tobacco plants were selected for double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) and polymerase chain reaction (PCR) identification analyses. Serological analyses were carried out in two repetitions and with the following polyclonal antisera: Potato virus Y (PVY) (Loewe Biochemica, Sauerlach, Germany); Tobacco mild green mosaic virus (produced in our laboratory); Tobacco mosaic virus (BIO-RAD, Marnes-La-Coquette, France); and Tomato spotted wilt virus (Loewe Biochemica). A simplified method of duplex PCR was used for a rapid, sensitive, and simultaneous detection of TYLCSV and TYLCV (2). Mixed infections of PVY and TYLCV were detected in all four tobacco samples tested. TYLCV infection was confirmed using the primer pair TY-1/TY-2 specific for the coat protein (CP) gene of begomoviruses (1). The CP fragment was digested with the restriction enzyme AvaII, and the pattern obtained corresponded to that obtained from TYLCV-infected tomato that served as a positive control. Two PCR products from different tobacco samples were sequenced and both showed 100% identity with the corresponding region (Almería) of TYLCV (GenBank Accession No. AJ489258) and 99% with TYLCV-Mild (Spain) (GenBank Accession No. AJ519441), confirming the diagnosis. The symptoms observed in the tobacco plants can not be attributed solely to TYLCV since the virus was present in a mixed infection with PVY. However, tobacco infected with TYLCV may serve as an important alternate host for TYLCV in the tomato cropping system. To our knowledge, this is the first report of N. tabacum as a natural host of TYLCV in Spain.

References: (1) G. P. Accotto et al. Eur. J. Plant Pathol. 106:179, 2000. (2) P. Martínez-Culebras et al. Ann. Appl. Biol. 139:251, 2001. (3) J. Navas-Castillo et al. Plant Dis. 81:1461, 1997.
Occurrence of Cacao swollen shoot virus in Litimé, the Main Cocoa-Producing Area of Togo
Authors: Cilas C. , Muller E. , Mississo E.
Published: May 2007

Cacao swollen shoot disease, first described from Ghana on Theobroma cacao in 1922, was identified in Togo in 1955 (4) in Kloto, a minor cocoa-producing area. Litimé is the main production zone in the country. However, its share of production has fallen from approximately 75% of national production in the 1980s to 55% currently because of aging plantations and new swollen shoot foci in this region that had previously been free of the disease. This disease is caused by Cacao swollen shoot virus (CSSV), of which the first isolate to be studied molecularly (Agoul) came from Kloto (1). Since then, the different cocoa-producing regions have been surveyed on several occasions and swollen shoot foci were detected for the first time in Litimé at the end of the 1990s. During 2000, symptomatic leaves were taken from trees which exhibited characteristic symptoms of the disease including swellings on fan branches and chupons, and red vein banding on young flush leaves. The existence of the virus was confirmed using immunosorbent electron microscopy (2) with a composite polyclonal Banana streak virus/Sugarcane bacilliform virus antiserum supplied by B. Lockhart and using polymerase chain reaction amplification with CSSV-specific primers (3). Degenerate primers for CSSV detection were designed in the 5′ region (the first 350 amino acids) of open reading frame (ORF3) because this region of the CSSV genome was found to be highly conserved among available full-length CSSV sequences. An isolate from the Litimé area (Wobe 12) was sequenced completely (Genbank Accession No. AJ781003), revealing that it shared a nucleotide sequence identity of only 77% with Agou1. Since the initial observations, the disease has spread rapidly and approximately 60% of the plots in Litimé contain infected trees. Hence, there is an urgent need for a program to rogue infected trees and replant with tolerant material. Moreover, this situation is a threat to cocoa plantations in neighboring Ghana, where numerous eradication operations to control this disease have been launched.

References: (1) L. Hagen et al. Virology 196:619, 1993. (2) B. E. L. Lockhart et al. Phytopathology 82:691, 1992. (3) E. Muller et al. J. Virol. Methods 93:15, 2001. (4) M. Partiot et al. Café Cacao Thé 22:217, 1978.
Distribution of Potebniamyces pyri in the U.S. Pacific Northwest and Its Association with a Canker and Twig Dieback Disease of Pear Trees
Authors: Xiao C. L. , Boal R. J.
Published: May 2007

Winter pears (Pyrus communis) in the United States are produced primarily in the Pacific Northwest. Potebniamyces pyri (anamorph Phacidiopycnis piri) is the causal agent of Phacidiopycnis rot, a recently reported postharvest disease on pears in the United States. Infection of fruit by P. pyri occurs in the orchard, and symptoms develop during storage. P. pyri was observed to be associated with cankers, dead bark, and twig dieback of pear trees. P. pyri was isolated from 40 to 50% of the twig samples exhibiting dieback symptoms from three commercial d'Anjou pear orchards, and 35% of dying bark samples from one orchard. However, little information is available regarding pathogenicity of P. pyri on pear trees. To determine the distribution of P. pyri, dying and dead bark samples were collected from pear orchards in various pear-producing areas in Oregon and Washington, and examined for presence of fruiting bodies (pycnidia or apothecia) of P. pyri. In the orchard, 2-year-old twigs were wounded using a sterile cork borer with or without spraying with a commercial aerosol tissue-freezing product at the wound sites. Wounds were then inoculated with either mycelial plugs from an agar medium or conidial suspensions of P. pyri. In a separate experiment, freshly made pruning wounds were inoculated with conidial suspensions of P. pyri. Canker development was monitored approximately monthly for up to 6 months after inoculation, at which time reisolation of P. pyri was attempted. P. pyri was found to be widespread in the Pacific Northwest. Incidence of trees infected by P. pyri based on presence of viable pycnidia in pear orchards ranged from 0 to 100%. Monthly tree inoculations in the orchard indicated that P. pyri in general did not cause cankers on non-cold-injured, wound-inoculated twigs, but apparently became established on cold-injured, wound-inoculated twigs and caused small cankers. Minor dieback developed on twigs inoculated at pruning wounds. At 6 months after inoculation, P. pyri was recovered from the majority of inoculated twigs. Thus, P. pyri appears to be a weak canker-causing pathogen on pear trees.
Effect of Barberry Eradication on Changes in Populations of Puccinia graminis in Minnesota
Authors: Peterson P. D. , Leonard K. J. , Roelfs A. P. , Sutton T. B.
Published: May 2007

Proportions of formae speciales of Puccinia graminis in collections of aeciospores from barberry were determined from cereal rust survey records from 1912 to 2002 in Minnesota. The frequency of P. graminis f. sp. avenae in aeciospore collections fluctuated between 0 and 10% from 1920 to 2002, even though oat was the dominant small grain crop in Minnesota until 1970. In early years, P. graminis f. sp. tritici was common, but the frequency of P. graminis f. sp. tritici in aeciospore collections declined to a low of 4% in the 1980s, whereas P. graminis f. sp. secalis increased to 96%. After 1990, the frequency of P. graminis f. sp. tritici increased and P. graminis f. sp. secalis declined in aecial collections, possibly indicating a changing proportion of P. graminis f. sp. secalis and tritici on wild grasses near barberry bushes. Diversity of races among uredinial collections of P. graminis f. sp. tritici from wheat in Minnesota declined sharply from 1912 to 1930 and remained low to 2002. Although the races of P. graminis f. sp. tritici most common in uredinial collections also were most common in the aecial collections in five of nine decades from 1912 to 1999 as well in the years 2000 to 2002, the diversity of races was greater among aecial than uredinial collections. Diversity in aecial collections remained nearly constant for 90 years, indicating a continuing contribution of the sexual stage to diversity of P. graminis f. sp. tritici.
Virulence of Oat Crown Rust in Mexico
Authors: Leonard K. J. , Huerta-Espino J. , Salmeron J. J.
Published: May 2007

Virulence of isolates of Puccinia coronata collected during 1992 to 1998 from Sonora, Chihua-hua, Nuevo Leon, and five states in Central Mexico were compared on a set of 27 differential oat (Avena sativa) lines with different genes for race-specific resistance. Frequencies of virulence and the presence of specific pathogenic races were compared among the four regions of Mexico and between Mexico and the adjoining states of California and Texas in the United States. The P. coronata populations in Mexico were highly diverse even though the sexual stage of the fungus is not known to occur there. Overall virulence frequencies were most similar between Chihuahua and Nuevo Leon, but there were more races in common between Central Mexico and Chihuahua than between any other pair of regions of Mexico. No races found in Sonora were found in other regions of Mexico. More races found in Texas also occurred in Nuevo Leon than in any other region of Mexico. Mean virulence complexity was lowest in isolates from central Mexico; greatest in Sonora, California, and Texas; and intermediate in Chihuahua and Nuevo Leon. Significant (P < 0.05) associations of virulences occurred for 24 pairs of virulence genes in at least three of the four regions of Mexico. Virulences to 19 of the 24 pairs were also significantly associated in Texas; virulences to 13 were also significantly associated in California.
Pathogenicity of Fungi Associated with the Wheat Crown Rot Complex in Oregon and Washington
Authors: Smiley Richard W. , Gourlie Jennifer A. , Easley Sandra A. , Patterson Lisa-Marie
Published: May 2007

Crown rot of wheat in the Pacific Northwest is caused by a complex including Bipolaris sorokiniana, Fusarium avenaceum, F. culmorum, F. pseudograminearum, and Microdochium nivale. Relative pathogenicity was examined under greenhouse conditions for 178 isolates of the five species, and under field conditions for 24 isolates of B. sorokiniana, F. culmorum, and F. pseudograminearum. In the greenhouse, all five species reduced (P < 0.05) plant height relative to noninoculated controls. Disease severity was inversely correlated with plant height for the three Fusarium spp. In one or more of four experiments with spring wheat in the field, all three species reduced stand establishment and density of mature heads and increased the incidence and severity of crown rot. F. culmorum and F. pseudograminearum caused the greatest disease severity and plant damage and were the only pathogens that reduced grain yield. Virulence ratings were variable among isolates for each species in all greenhouse and field experiments. Isolate variability was especially high for the location and year variables in field experiments. Mixtures of multiple isolates are required for future research.
Suppression of Wheat Growth and Yield by Pratylenchus neglectus in the Pacific Northwest
Authors: Smiley Richard W. , Whittaker Ruth G. , Gourlie Jennifer A. , Easley Sandra A.
Published: May 2007

Many wheat (Triticum aestivum) fields planted annually in the Pacific Northwest are infested by high populations of the lesion nematode, Pratylenchus neglectus. Spring wheat cultivars varying in tolerance and resistance to P. neglectus were treated or not treated with aldicarb to examine relationships between the nematode and growth and yield of annual direct-seeded (no-till) wheat. Increasing initial density of P. neglectus in soil was more strongly associated with declining growth and yield of intolerant (Machete and Spear) than moderately tolerant (Frame and Krichauff) cultivars. Yield suppression by P. neglectus was generally 8 to 36% for intolerant cultivars, but reached 71% in soil also harboring Heterodera avenae, Rhizoctonia solani AG-8, and Gaeumannomyces graminis var. tritici. Intolerant cultivars had lower yields than Krichauff in rainfed but not in irrigated experiments. Density of P. neglectus in mature roots was generally lower for moderately resistant Krichauff than for susceptible Machete and Spear. Aldicarb improved yields in irrigated but not in rainfed experiments, and increased plant height and reduced variability in tiller height, canopy temperature, and density of P. neglectus in roots. This is the first report of damage to wheat by P. neglectus in the Pacific Northwest. Breeding wheat for tolerance and resistance to P. neglectus is suggested.
Effects of Plant Spacing, Inoculation Date, and Peanut Cultivar on Epidemics of Peanut Stem Rot and Tomato Spotted Wilt
Authors: Sconyers L. E. , Brenneman T. B. , Stevenson K. L. , Mullinix B. G.
Published: May 2007

Two microplot studies were conducted with peanut (Arachis hypogaea L.) in 2000, 2001, and 2002 to determine the effects of plant spacing, inoculation date, and cultivar on stem rot development caused by Sclerotium rolfsii Sacc., tomato spotted wilt incidence, and microclimate (temperature and relative humidity). Stem rot severity and incidence decreased as plant spacings were increased in 5-cm increments from 5 to 30 cm. Two cultivars with similar susceptibility but different growth habits were compared. Perhaps due to heavy irrigation and extensive vegetative growth, stem rot was similar for ‘Florida MDR-98’ and ‘Georgia Browne’. Plants inoculated later in the year (90 days after planting [DAP]) had less disease at harvest, but often developed more severe symptoms within the first week of inoculation than plants inoculated at 50 or 70 DAP. Canopy microclimate was different than ambient conditions for all treatments; however, differences among treatments were inconsistent and did not explain differences in disease among spacings. Generally, as plant spacing decreased and plant population increased, stem rot increased and tomato spotted wilt was reduced. These data demonstrate that the physical spacing between plants is a critical factor in disease development.
Yield Loss Potential of Phaeosphaeria Leaf Spot of Maize Caused by Phaeosphaeria maydis in the United States
Authors: Carson M. L.
Published: May 2007

The ability of Phaeosphaeria leaf spot (PLS) to reduce yields of maize was evaluated over two winter growing seasons in southern Florida. Nine commercial maize hybrids, varying in reaction to PLS, were planted in a split-plot design with hybrids as whole plots and inoculated versus uninoculated treatments as subplots. The most susceptible hybrid, Pioneer brand 3489, sustained a significant reduction in grain yield (11 to 13%) and 400-kernel weight (5 to 10%) in the trials. Regression analyses indicated that grain yields and 400-kernel weights were reduced 0.23 and 0.16%, respectively, for each percent increase in PLS severity at the mid-dent stage. Because most U.S. maize hybrids are resistant, and PLS develops late in the grain-filling period, its potential to cause substantial losses in the United States appears limited at this time.
First Report of Phytophthora cryptogea Root and Crown Rot on Peach Trees in Chile
Authors: Guzmán G. , Latorre B. A. , Wilcox W. F.
Published: May 2007

Phytophthora cryptogea Pethybridge and Lafferty was consistently isolated from the Nemaguard rootstock (Prunus persica × P. davidiana) of peach trees in Chile. Symptoms included reddish necrotic tissues at the base of the trunk often extending to the main roots, root rot, gummosis, foliar chlorosis, lack of vigor, and dieback, with severely infected trees dying. Isolations with corn meal agar (Difco, Detroit, MI) amended with antibiotics and fungicides (ACMA) (2) and pure cultures were obtained by hyphal tip transfers to ACMA. Ten isolates from different locations were identified by morphology and growth at cardinal temperatures (1). These isolates produced hyphal swellings and sporangia by using carrot juice broth (2) for 48 h followed by the addition of 1% (w/v) nonsterilized soil extract. Sporangia were nonpapillate, internally proliferating, noncaducous, ovoid to obpyriform, and with mean dimensions of 36 × 24 μm. All isolates were typed as A1 using a P. cinnamomi A2 culture as the test isolate and produced oospores on clarified V8 juice agar amended with thiamine, tryptophan, and β-sitosterol (2) after 15 to 30 days at 20°C in the dark. Mycelia grew between 5 and 30°C, with optimal growth at 20°C and no growth at 35°C. The ITS sequence analysis performed by IMI (CABI Bioscience, Wallingford, UK) indicated a close match with P. cryptogea, P. drechsleri, and P. erythroseptica, however, peach isolates were differentiated from P. drechsleri and P. erythroseptica by the absence of mycelial growth at 35°C and the heterothallic production of oospores, respectively. Four P. cryptogea isolates were pathogenic when inoculated onto 1-year-old twigs detached from a Nemaguard tree, causing reddish necrotic lesions varying from 7 to 29 mm long after 15 days of incubation at 20°C. Two-year-old P. persica var. nectarina cv. Ruby Diamond budded on Nemaguard and cultivated in 100-liter containers in open field conditions were inoculated with 500-ml of a mycelial suspension (4.5 × 106 propagules per ml) per plant added to 15-cm-deep holes around the trunk. Plants were immediately irrigated and maintained at field capacity during the experiment. An equal number of noninoculated trees treated similarly were left as controls. During the spring, plants developed a general chlorosis and declined within 90 days postinoculation. Tests were repeated with similar results. In other preliminary tests, plants developed cankers characterized by gumming and reddish necrotic lesions underneath the bark following trunk inoculations with mycelium in agar of the same isolates obtained on ACMA. These tests were also repeated. The pathogen was consistently reisolated from symptomatic tissue. To our knowledge, this is the first report of P. cryptogea as a pathogen on peach trees in Chile.

References: (1) F. J. Newhook et al. Mycol. Pap. No. 143. CMI, Kew, Surrey, UK, 1978. (2) W. F. Wilcox and B. A. Latorre. Plant Dis. 86:1357, 2002.
Widespread Distribution of Apple mosaic virus on Apple in Turkey
Authors: Akbaş B. , Ilhan D.
Published: May 2007

From 2002 to 2003, symptoms suggestive of Apple mosaic virus (ApMV; a member of the genus Ilavirus) infection on apple (Malus pumila L.) trees were observed in orchards in the central Anatolia Region of Turkey. Symptoms on leaves included pale-to-bright cream spots, mosaic, and yellowing on the leaves. A survey was conducted during May and June in three provinces (Isparta, Karaman, and Niğde) for disease symptoms. Leaf samples from apple cvs. Anna, Gala, Gold Star, Golden Delicious, Granny Smith, Jonathan, Starking, and Rajka were collected and tested for the presence of ApMV with specific antisera (Agdia, Elkhart, IN) using the manufacturer's protocol for double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). ApMV was found in 68.3% of 461 samples tested. The number of samples for each cultivar tested and percent positive for ApMV were as follows: 22 (9.1%), 34 (8.8%), 22 (13.6%), 30 (73.3%), 270 (95.5%), 46 (54.3%), and 22 (9.1%) for cvs. Anna, Gala, Gold Star, Golden Delicious, Granny Smith, Starking, and Rajka, respectively. All 15 samples tested of cv. Jonathan were negative using DAS-ELISA. Samples that tested positive for ApMV were mechanically inoculated onto Chenopodium amaranticolor, C. quinoa, and Cucumis sativus leaves using an inoculum prepared by homogenizing leaves in phosphate buffered saline containing 2.5% (vol/vol) nicotine. Inoculated C. quinoa showed inconspicuous mottling, and Cucumis sativus showed chlorotic local lesions that progressed to systemic chlorosis and stunting. No symptoms were observed on inoculated C. amaranticolor as previously reported for ApMV (3,4). The presence of ApMV in C. quinoa and Cucumis sativus were verified using DAS-ELISA, but ApMV was not detected in C. amaranticolor. Although ApMV has been reported in several different crops in Turkey, there have been only two unsubstantiated reports of ApMV-infected apple in the country (1,2). This study conclusively demonstrates ApMV infection of apples in Turkey and suggests that it is widely spread.

References: (1) Ü. Fidan. J. Turk. Phythopathol. 23:3, 127, 1994. (2) M. Özkan and S. Kurçman. Bitki Koruma Bül. 16:106, 1976. (3) S. J. Petybridge et al. Ann. Appl. Biol. 141:77, 2002. (4) T. Sano et al. Ann. Appl. Biol. 106:305, 1985.
A Survey of Viruses Affecting French bean (Phaseolus vulgaris) in Iran Includes a First Report of Southern bean mosaic virus and Bean pod mottle virus
Authors: Shahraeen N. , Ghotbi T. , Elkhache A. Dezaje , Sahandi A.
Published: May 2007

A survey was conducted from 2003 to 2004 to identify viruses infecting common bean (Phaseolus vulgaris L.) in different growing areas of East Azarbaejan Province of Iran. A total of 300 French bean samples with symptoms of viral infection (mosaic, vein clearing, leaf rolling, yellowing, and leaf distortion) were collected. The samples were tested for eight viruses using the tissue-blot immunoassay procedures (TBIA) (2) and double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) according to the manufacturer's instructions (DSMZ, Braun-schweig, Germany). ELISA tests for Alfalfa mosaic virus (AMV), Bean yellow mosaic virus (BYMV), Bean common mosaic virus (BCMV), Bean common mosaic necrosis virus (BCMNV), Cucumber mosaic virus (CMV), Bean leaf roll virus (BLRV), and Southern bean mosaic virus (SBMV) were used. In addition, antiserum was provided by S. A. Ghabrial (University of Kentucky, Lexington) to test for Bean pod mottle virus (BPMV). Serological tests showed that SBMV and BPMV were present in 12% (35 samples) and 5% (15 samples) of samples, respectively. BCMV, BCMNV, BYMV, BLRV, CMV, and AMV were more common and were detected in 155, 105, 80, 46, 30, and 10 samples of 300 samples, respectively. These six viruses were previously reported in other pulses and in French bean in Iran (1). The presence of SBMV and BPMV were verified in samples by transmission to French bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), and soybean (Glycine max) indicator test plants (3,4). Inoculation with extracts from SBMV-positive plants produced systemic mottle and mosaic symptoms in soybean (cv. Gorgan-3) and French bean (cvs. Dubbele Witte and Cheete). In cowpea (cv. Mashad) and French bean (cv. Pinto), inoculation produced necrotic local lesions. Inoculation with extracts from BPMV-positive plants produced severe mosaic, leaf distortion, and puckering in soybean (cv. Gorgan-3) and French bean (cv. Ten-dergreen). No symptoms were observed in cowpea (cv. Mashad). Cvs. Pinto and Bountiful bean reacted with necrotic local lesions. All indicator test plants tested positive for the presence of SBMV or BPMV as expected using DAS-ELISA. To our knowledge, this is the first report of BPMV and SBMV naturally infecting French bean in Iran. These viruses can cause a serious problem to other leguminous crops grown in Iran.

References: (1) W. J. Kaiser et al. Plant Dis. Rep. 52:687, 1968. (2) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994. (3) J. S. Semancik. Bean pod mottle virus. No. 108 in: Descriptions of Plant Viruses. CMI/AAB, Kew, Surrey, England, 1972. (4) J. H. Tremain and R. I. Hamilton. Southern bean mosaic virus. No. 274 in: Descriptions of Plant Viruses. CMI/AAB, Kew, Surrey, England, 1983.