bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Isolates of Tomato spotted wilt virus Overcoming Resistance in Pepper and Their Spread to Other Hosts in Italy
Authors: Roggero Piero , Masenga Vera , Tavella Luciana
Published: May 2007

Isolates of Tomato spotted wilt virus (TSWV) severely and systemically infecting commercial pepper cultivars with resistance introgressed from Capsicum chinense PI152225 were found in Albenga (northwestern Italy) in July 2000. Experimentally, these resistance-breaking (RB) isolates overcame the resistance in C. chinense PI152225, but they produced infection in other hosts similarly to non-RB isolates from the same area. The RB isolates were indistinguishable from TSWV by serology and electron microscopy, and they were efficiently transmitted by Frankliniella occidentalis. Such isolates were recovered on the same farm in tomato, pepper, and artichoke 2 and 12 months later, suggesting natural spread from the resistant plants and survival. The RB isolates survived in experimental mixed infections with a non-RB isolate in susceptible pepper and C. chinense, but cross-protection in pepper acted against them. Commercial TSWV-resistant pepper but not resistant tomato cultivars from different companies were susceptible to these RB isolates after mechanical inoculation. Similar isolates were not detected among TSWV samples collected from 1993 to 2000 in the area. The management of TSWV and thrips using resistant pepper cultivars is discussed.
Foliar Disease in Fresh-Market Tomato Grown in Differing Bed Strategies and Fungicide Spray Programs
Authors: Mills Douglas J. , Coffman C. Benjamin , Teasdale John R. , Everts Kathryne L. , Abdul-Baki Aref A. , Lydon John , Anderson James D.
Published: May 2007

A 3-year field study in central Maryland evaluated foliar disease in fresh-market tomato grown using combinations of four bed strategies and three fungicide programs. Bed strategies included uncovered beds with or without a composted dairy manure amendment or beds covered with black polyethylene or hairy vetch mulch. Fungicide programs included no fungicide, weekly fungicide, or fungicide applications scheduled according to the TOMCAST disease predictor. In plots with hairy vetch-covered beds, early blight caused by Alternaria solani, Septoria leaf spot caused by Septoria lycopersici, and defoliation were lower versus uncovered beds each year. Early blight and defoliation were lower in beds covered with vetch versus polyethylene mulch in 2 of 3 years. Disease severity, defoliation, and marketable yield were similar for the weekly and TOMCAST fungicide programs, with 40 to 50% fewer sprays using TOMCAST. Marketable yield was similar among bed strategies except for higher yields in covered versus uncovered and unamended beds in a relatively wet year and lower yields in vetch versus polyethylene beds in a dry year.
Physiologic Specialization of Puccinia triticina on Wheat in the United States in 2000
Authors: Long D. L. , Kolmer J. A. , Leonard K. J. , Hughes M. E.
Published: May 2007

Collections of Puccinia triticina were obtained from rust infected wheat leaves by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio Valley, Gulf Coast, and Atlantic Coast States in order to determine the virulence of the wheat leaf rust fungus in 2000. Single uredinial isolates (1,120 in total) were derived from the wheat leaf rust collections and tested for virulence phenotype on 16 lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes. In the United States in 2000, 54 virulence phenotypes of P. triticina were found. Virulence phenotypes MBDS and MCDS, which are virulent to resistance gene Lr17, were the first and third most common phenotypes in the United States and were found in the Great Plains and the Ohio Valley regions. MCRK, which is virulent to Lr26, was the second most common phenotype and was found primarily in the Southeast, Ohio Valley, and Northeast regions. In the northern area of the Great Plains, phenotypes with virulence to Lr16 increased in frequency from 1998 and 1999. The Southeast and Great Plains regions had different predominant virulence phenotypes, which indicates that populations of P. triticina in those areas are not closely connected. The northern and southern areas of the Great Plains region had the same predominant virulence phenotypes, indicating movement of virulence phenotypes of P. triticina within this region.
Biological Control of Sclerotinia Stem Rot of Soybean with Sporidesmium sclerotivorum
Authors: del Rio L. E. , Martinson C. A. , Yang X. B.
Published: May 2007

Field studies were conducted to evaluate the effectiveness of Sporidesmium sclerotivorum to control Sclerotinia stem rot of soybean (SSR) at Ames, Humboldt, and Kanawha, IA, between 1996 and 1998. Experimental plots (3 × 3 m) were infested with S. sclerotivorum macroconidia once at a rate of 0, 2, or 20 spores per cm2 in the fall of 1995 or the spring of 1996, under two crop rotation schemes. A randomized complete block design with four replications in each location was used. Plots infested with 20 spores per cm2 had 62% less SSR (P = 0.05) than control plots at Humboldt in 1996. No differences were detected between fall and spring applications. In 1998, plots treated with either 2 or 20 spores per cm2 had 51 to 63% less SSR (P = 0.05) than control plots at Ames and Kanawha. In 1998, SSR was completely suppressed in all plots at Humboldt, while the commercial field surrounding the experimental plots had 17% SSR. S. sclerotivorum was retrieved from all infested plots at all locations 2 years after infestation with sclerotia of Sclerotinia sclerotiorum as bait. At Humboldt, S. sclerotivorum was also retrieved from control plots. Two larger plots (10 × 10 m) were infested with 20 or 100 spores per cm2 in the fall of 1996 or spring of 1997 in six commercial fields. SSR incidence, which was measured in transects up to 20 m from the infested area at 5-m intervals, was reduced 56 to 100% (P = 0.05) in four fields compared with the surrounding uninfested areas in the commercial fields. Dispersal of the control agent was evident by the fact that SSR incidence gradually increased from the edge of the infested macroplots up to about 10 m into noninoculated areas of the commercial field. This paper constitutes the first report describing the biocontrol of a disease on field crops that may be employed economically.
First Report of Cacopsylla picta as a Vector of Apple Proliferation Phytoplasma in Germany
Authors: Jarausch B. , Schwind N. , Jarausch W. , Krczal G. , Dickler E. , Seemüller E.
Published: May 2007

Since 2000, a serious epidemic of apple proliferation (AP) reappeared in southwestern Germany. Molecular analyses revealed that the AP phytoplasma is associated with this disease. Since no curative treatments or resistant cultivars exist, the only means to reduce spread of the disease is the control of the insect vector. Recently, Frisinghelli et al. (1) identified Cacopsylla costalis as a vector of AP phytoplasma in northern Italy. Following this result, transmission trials with C. picta (synonym C. costalis) were conducted in southwestern Germany at Neustadt (Rheinland-Pfalz) and Dossenheim (Baden-Württemberg) since 2001. Overwintering psyllids were captured from March to May in different orchards. Groups of 5 to 30 C. picta were caged for 2 to 4 weeks on apple seedlings or healthy micropropagated plants. Leaf midribs of test plants were sampled 2 to 3 months after inoculation feeding and tested by polymerase chain reaction (PCR) for AP phytoplasma with specific primers AP5/AP4 (2). In 2001, 1 of 10 test plants, and in 2002, 7 of 40 test plants became AP infected. In 2002, one to four C. picta specimens fed on plants which became infected were tested AP phytoplasma positive by PCR while all psyllids recollected from PCR-negative plants were tested negative. Transmission of the AP phytoplasma was successful at both sites. To our knowledge, this is the first report of C. picta as a vector of the AP phytoplasma in Germany.

References: (1) C. Frisinghelli et al. J. Phytopathol. 148:425, 2000. (2) W. Jarausch et al. Appl. Environ. Microbiol. 60:2916, 1994.
First Report of Wilt and Dieback on Pokeweed (Phytolacca decandra) Caused by Phytophthora nicotianae
Authors: Belisario A. , Maccaroni M. , Corazza L.
Published: May 2007

Pokeweed (Phytolacca decandra, synonym Phytolacca americana) is a root perennial plant that produces a succulent annual stem. In late June 2001, a severe dieback occurred on a group of pokeweed plants being grown as ornamentals in a garden in Rome. Disease symptoms consisted of leaf wilting followed by collapse of the plant. Stem collars and roots had dark brown-to-black water-soaked lesions. A wet rot was observed on plants with advanced disease symptoms. Isolations, from sections of roots and stems previously washed in running tap water, were made on PARBhy selective medium (10 mg of pimaricin, 250 mg of ampicillin [sodium salt], 10 mg of rifampicin, 50 mg of hymexazol, 15 mg of benomyl, 15 g of malt extract, and 20 g of agar in 1,000 ml of H2O) (2), followed by incubation at 20°C. A species of Phytophthora identified based on morphological and cultural characteristics (1) was isolated consistently from rotted roots and collars of diseased plants. All isolates produced papillate, spherical, ovoid to obturbinate, noncaducous sporangia and terminal and intercalary chlamydospores. Hyphal swellings with hyphal outgrowths were present. Observed characteristics were similar to those described for P. nicotianae. Isolates were mating type A2 with amphigynous antheridia in paired cultures with the A1 tester isolate of P. nicotianae. Identification was confirmed by comparing restriction fragment length polymorphism patterns of the internal transcribed spacer region of ribosomal DNA with those obtained from previously identified Phytophthora species. Pathogenicity tests were conducted on 10 2-month-old potted pokeweed plants. Inoculum was prepared by inoculating sterilized millet seeds moistened with V8 broth with plugs of mycelium and growing for 4 weeks. The inoculum was added to potting soil at 3% (wt/vol), and sporulation was induced by flooding the soil for 48 h. Five uninoculated plants were used as controls. Plants were maintained outdoors and assessed for symptoms within 2 months after inoculation. Wilting, root rot, and dark brown lesions on the collar developed on inoculated plants. The pathogen was reisolated from the inoculated plants and morphologically identical to the original isolates, which confirmed P. nicotianae as the causal agent of the disease. Few diseases have been reported on Phytolacca decandra. This species is not only an invasive weed, but is also cultivated as an ornamental and medicinal plant. In addition, antiviral (PAP) and antifungal (Pa-AFP) proteins that are used as a remedy for several human and plant infections have been extracted from the plant. To our knowledge, this is the first report of P. nicotianae on pokeweed.

References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) A. M.Vettraino et al. Plant Pathol. 50:90, 2001.
First Report of Tomato spotted wilt virus in Blackberry Lily in North America
Authors: Adkins S. , Breman L. , Baker C. A. , Wilson S.
Published: May 2007

Blackberry lily (Belamcanda chinensis (L.) DC.) is an herbaceous perennial in the Iridaceae characterized by purple-spotted orange flowers followed by persistent clusters of black fruit. In July 2002, virus-like symptoms including chlorotic ringspots and ring patterns were observed on blackberry lily leaves on 2 of 10 plants in a south Florida ornamental demonstration garden. Inclusion body morphology suggested the presence of a Tospovirus. Tomato spotted wilt virus (TSWV) was specifically identified by serological testing using enzyme-linked immunosorbent assay (Agdia, Elkhart, IN). Sequence analysis of a nucleocapsid (N) protein gene fragment amplified by reverse transcription-polymerase chain reaction (RT-PCR) with primers TSWV723 and TSWV722 (1) from total RNA confirmed the diagnosis. Nucleotide and deduced amino acid sequences of a 579 base pair region of the RT-PCR product were 95 to 99% and 95 to 100% identical, respectively, to TSWV N-gene sequences in GenBank. Since these 2-year-old plants were grown on-site from seed, they were likely inoculated by thrips from a nearby source. Together with a previous observation of TSWV in north Florida nursery stock (L. Breman, unpublished), this represents, to our knowledge, the first report of TSWV infection of blackberry lily in North America although TSWV was observed in plants of this species in Japan 25 years ago (2).

References: (1) S. Adkins, and E. N. Rosskopf. Plant Dis. 86:1310, 2002. (2) T. Yamamoto and K.-I. Ohata. Bull. Shikoku Agric. Exp. Stn. 30:39, 1977.
Relation of Temperature and Rainfall to Development of Xanthomonas and Pantoea Leaf Blights of Onion in Colorado
Authors: Schwartz Howard F. , Otto Kristen L. , Gent David H.
Published: May 2007

During the 1996 to 1999 growing seasons, some areas of Colorado's onion-growing regions experienced a complex of bacterial diseases including leaf blights caused by Xanthomonas campestris and Pantoea ananatis. Crop losses varied depending on adverse weather (associated with rain, storm, and temperature patterns) and stage of onion plant development. Environmental conditions during vegetative development had no significant association with the initial appearance or subsequent intensity of disease. Both pathogens were active at average high temperatures that ranged from 28 to 35°C during bulbing. Multiple regression models were developed to predict the initial appearance (growing degree day [GDD]) and subsequent Xanthomonas leaf blight intensity (final proportion of disease [FPD]) using macroclimatic meteorological conditions, including July average daily high temperature (Tjmax), August cumulative rainfall (Pa), and cumulative rainfall in July and August (Pja). Initial disease appearance and disease intensity were described by GDD10 = -6,153.43 + 215.50Tjmax - 0.92Pa and FPD = 222.79 - 6.92Tjmax + 0.52Pja, respectively. Pantoea leaf blight initial appearance was strongly associated with July average daily temperatures (Tj) and was described by GDD10 = -5,930.43 + 289.07Tj. Results are discussed in relation to an integrated pest management strategy in Colorado.
Resistance of Geneva and Other Apple Rootstocks toErwinia amylovora
Authors: Norelli J. L. , Holleran H. T. , Johnson W. C. , Robinson T. L. , Aldwinckle H. S.
Published: May 2007

When vigorously growing shoots of 49 different apple rootstocks grown in a greenhouse were inoculated with different strains of Erwinia amylovora, Budagovsky 9 (B.9), Ottawa 3, Malling 9, and Malling 26 were the most fire blight susceptible rootstocks and Geneva 11, Geneva 65, Geneva 16, Geneva 30, Pillnitzer Au51-11, Malling 7, and several breeding selections were the most resistant. Significant strain—rootstock interactions were observed in the amount of fire blight that resulted from inoculation. Field-grown fruiting ‘Royal Gala’ trees on Geneva 16 and Geneva 30 rootstocks were highly resistant to rootstock infection (no tree mortality) when trees sustained severe blossom infection with E. amylovora, compared with Malling 9 and Malling 26 rootstock clones, which were highly susceptible to infection (36 to 100% tree mortality). In contrast to potted own-rooted B.9 plants inoculated in a greenhouse, B.9 rootstocks of orchard trees appeared resistant to rootstock infection (0% tree mortality). Orchard trees on Geneva 11 were moderately resistant to rootstock infection (25% tree mortality). There was general agreement in the evaluation of resistance under orchard conditions when rootstock resistance was evaluated in relation to controlled blossom inoculation or to natural blossom infection.
Analysis of Spatiotemporal Dynamics of Virus Spread in an Australian Hop Garden by Stochastic Modeling
Authors: Pethybridge Sarah J. , Madden L. V.
Published: May 2007

The dynamics of spread of Hop latent virus (HpLV), Hop mosaic virus (HpMV), and Apple mosaic virus (ApMV) in an Australian hop garden were characterized by fitting a stochastic spatiotemporal model, using the Monte Carlo Markov Chain (MCMC) method, to the changes in patterns of virus-infected plants. The model has parameters for background infection rate (from virus reservoirs outside the gardens) and local infection rate (spread from infected plants to virus-free plants). The HpLV epidemic could be explained by very short range spread within the garden, suggesting mechanical transmission through cultural operations. This is consistent with the absence of the only known aphid vector of HpLV from Australia. The HpMV epidemic could be explained by local spread coupled with background infection. This suggests that HpMV may be introduced by aphids, and subsequent localized spread may occur by aphids or mechanical means. The ApMV epidemic was also consistent with localized spread coupled with background infection, but the possibility of longer-range spread could not be rejected for this virus. Although intra-garden transmission of ApMV may occur through contact or cultural operations, these results suggest that other mechanisms could contribute to transmission of ApMV in Australian hop gardens. Join-count statistics for the patterns of infected plants supported the conclusion from the spatiotemporal modeling that short-range spread was the primary determinant of disease increase.
Fungicide Seed Treatment Effects on Seedling Damping-off of Pumpkin Caused by Phytophthora capsici
Authors: Babadoost M. , Islam S. Z.
Published: May 2007

Apron XL LS (mefenoxam) and Allegiance FL (metalaxyl) were highly inhibitory to growth of mycelium of Phytophthora capsici in vitro. Effective dose (ED50) of mefenoxam and metalaxyl for 50% inhibition of mycelial growth, for all five isolates of P. capsici tested, was 0.98 and 0.99 μg a.i./ml of culture medium, respectively. For mefenoxam at 200 μg a.i./ml, sporangium and zoospore germination were reduced by 92 and 96%, respectively, and 21 and 24%, respectively, for metalaxyl. In greenhouse studies, seed treatment with mefenoxam (0.42 ml of Apron XL LS/kg of seed) and metalaxyl (0.98 ml of Allegiance FL/kg of seed) significantly reduced pre- and post-emergence damping-off of seedlings caused by P. capsici in three pumpkin cultivars (Dickinson, Hybrid-401, and Hybrid-698) tested. Thirty-one days after seeding, at inoculum levels of 0, 90, 600, 1,400, and 4,000 CFU/g of soil, the average seedling stands for mefenoxam treatment were 98.4, 93.8, 88.3, 77.8, and 64.8%; for metalaxyl, 99.1, 85.3, 85.8, 73.5, and 59.3; and for the untreated control, 97.5, 55.2, 45.7, 37.0, and 22.9%, respectively. In field trials, the average seedling stands 35 days after seeding were 76.7, 74.7, and 44.9% for mefenoxam, metalaxyl, and untreated control, respectively. Seed treatment with mefenoxam or metalaxyl did not have any significant effect on either seed germination or seedling vigor.
Occurrence of Stem Rot of Chrysanthemum Caused by Sclerotinia sclerotiorum in Argentina
Authors: Wright E. R. , Palmucci H. E.
Published: May 2007

Chrysanthemum (Dendranthema × grandiflorum (Ramat.) Kitam.) is one of the most popular flowering plants in Argentina. A previously undescribed stem rot disease was observed in cvs. Alba and Palisade in greenhouses near Buenos Aires and La Plata, an area of intensive floriculture production. The stem was killed within 10 to 15 days causing the plant to wilt and die. Necrotic tissues were covered with whitish mycelium that produced black, irregular shaped (3 to 7 mm diameter) sclerotia. The pathogen was isolated from symptomatic stem sections, surface disinfested for 1 min in 2% NaOCl, and plated on potato dextrose agar (PDA) (1, slightly modified). The organism isolated produced white aerial mycelia and large number of sclerotia characteristic of Sclerotinia sclerotiorum (Lib.) de Bary. Symptoms were reproduced in the greenhouse by inoculating stems of 10 3-month-old plants with five mycelial plugs per plant from 7-day-old PDA cultures. Inoculated plants were enclosed in transparent plastic bags for 6 days with near saturation humidity and incubated in a growth chamber at 22 to 24°C with a 12-h photoperiod. Control plants were treated similarly except agar disks did not contain the fungus. After 6 to 9 days, symptoms were similar to those previously observed, and infected plants died 3 weeks after inoculation. No disease symptoms were observed on uninoculated plants. Koch's postulates were satisfied after reisolating the fungus. To our knowledge, this is the first report of the occurrence of white mold caused by S. sclerotiorum on chrysanthemum in Argentina. The disease has been previously observed in Argentina on lisianthus (Eustoma grandiflora (Raf.) Shinn.) in 1988 (2) and on carnation (Dianthus caryophyllus L.) in 1991, among other floriculture crops of economic importance.

References: (1) A. Garibaldi et al. Plant Dis. 85:446, 2001. (2) S. Wolcan et al. Plant Dis. 80:223, 1996.
Application of Preplant Fumigants via Drip Irrigation Systems for the Management of Root Rot of Melons Caused by Monosporascus cannonballus
Authors: Stanghellini M. E. , Ferrin D. M. , Kim D. H. , Waugh M. M. , Radewald K. C. , Sims J. J. , Ohr H. D. , Mayberry K. S. , Turini T. , McCaslin M. A.
Published: May 2007

Root rot and vine decline, caused by Monosporascus cannonballus, is a destructive disease of melons in the desert production regions of southern California. In 1998, we initiated studies on the use of preplant fumigation to reduce resident pathogen populations in soil. Preplant fumigation with methyl iodide injected as a hot gas at 448.4 kg/ha through drip irrigation tape in preformed, tarped beds consistently provided significant (P < 0.05) reductions in the percentage of roots infected compared with the nonfumigated controls; these reductions were equal to or better than those achieved with an equivalent rate (448.4 kg/ha) of methyl bromide. Chloropicrin applied in water at 249.0 kg/ha through buried drip irrigation tape to either tarped or nontarped beds significantly (P < 0.05) reduced the percentages of both roots infected and roots on which perithecia were produced compared with nonfumigated controls.
Effect of Soil Moisture Content on the Survival of Ganoderma Species and Other Wood-Inhabiting Fungi
Authors: Chang TunTschu
Published: May 2007

The survival of mycelia of Ganoderma australe, G. boninense, G. lucidum, and G. weberianum in colonized wood was measured in soils with different soil matrix potentials. Survival of mycelia of G. australe and G. boninense, which do not produce chlamydospores, buried in plots subjected to different soil moisture treatments, declined rapidly, and the fungi could not be recovered after 9 to 12 weeks. Survival of mycelia of G. lucidum and G. weberianum, which produce chlamydospores, rapidly declined from 0 to 15 weeks of incubation but consistently ranged from 35 to 50% after 15 weeks of incubation. In regression analyses for each of the four Ganoderma species, there was no difference in the rate of change of mycelial survival over time among different soil moisture treatments. However, when data from only the -0.20 MPa treatment were used, the rates of change of mycelia survival over time of G. australe and G. boninense significantly differed from those of G. lucidum and G. weberianum. G. australe and G. boninense were not recovered from pieces of infested wood subjected to 3 and 1 months of flooding, respectively. In treatments with lower soil moisture, the survival of these two fungi ranged from 80 to 90% over 2 years. In all soil moisture treatments, survival of G. lucidum and G. weberianum ranged from 80% to more than 90% over 2 years. Similarly, seven species of other wood-inhabiting fungi that do not produce chlamydospores were not recovered from pieces of infested wood subjected to 1 or 5 months of flooding, but chlamydospore-producing species were recovered. These results indicate that, regardless of chlamydospore formation, woody debris in soils harboring wood-decay fungi may be important for long-term survival, and chlamydospores of Ganoderma in woody debris enhance the resistance of the fungi to environmental stresses such as flooding. Flooding infested fields may help control those woodinhabiting fungi such as G. australe and G. boninense that do not produce chlamydospores.
Outbreak of Tobacco streak virus Causing Necrosis of Cucumber (Cucumis sativus) and Gherkin (Cucumis anguria) in India
Authors: Krishnareddy M. , Devaraj  , Raman Lakshmi , Jalali Salil , Samuel D. K.
Published: May 2007

Cucumber (Cucumis sativus L.) and Gherkin (Cucumis anguria L.) are important cucurbitaceous vegetables grown in India for slicing and pickling. During the 2000 to 2002 rainy season and summer, a new virus disease, causing yield losses of 31 to 75% in Bangalore, Bellary, Davanagiree, and Tumkur districts of Karnataka State, infected cucumber and gherkin. Symptoms were tip necrosis characterized by necrotic lesions on leaves, and a general leaf and stem necrosis extending to mid veins, petioles, flower buds and tip, eventually resulting in dieback of vines. Tissue extracts from symptomatic leaves of cucumber and gherkin were mechanically inoculated on several herbaceous indicator plants (cowpea, cucumber, pepper, Zinnia, watermelon, Chenopodium amaranticolor, sunflower, Nicotiana glutinosa, N. tabacum, and Gomphrena globosa). On most hosts, symptoms of chlorotic or necrotic lesions followed by mottle or systemic necrosis were observed. Back-inoculation from the symptomatic indicator plants onto cucumber and gherkin resulted in symptoms typical of those observed in the field. Electron microscopic examination of leaf-dip preparation and ultra thin sections of virus infected plant samples showed the presence of isometric particles 25 to 28 nm in diameter. Similar types of particles were observed when infected samples were trapped in immunosorbent electron microscopy with polyclonal antibodies specific to Tobacco Streak virus (TSV) but not to Watermelon silver mottle virus (WSMV). Enzymelinked immunosorbent assay tests using leaf extracts of field-collected samples and sap-inoculated plants showed positive reaction to antibodies of TSV (1) but not to antibodies of Cucumber mosaic virus, WSMV, Watermelon bud necrosis virus, Papaya ring spot virus W strain, and Zucchini yellow mosaic virus. Reverse transcription-polymerase chain reaction (RT-PCR) of RNA extracts of infected samples of field and inoculated symptomatic plants was done by using primers derived from TSV RNA3 specific for the coat protein (CP) region of TSV (2). A 800-bp specific DNA fragment was amplified from infected cucumber and gherkin but not from healthy control plants. Sequence analysis of cloned PCR fragments revealed nucleotide identities of 99% with TSV isolates from cotton, mungbean, sunnhemp, and sunflower (GenBank Accessions Nos. AF515824, AF515823, AF515825, and AY061929) and 88% with TSV-WC (GenBank Accession No. X00435). On the basis of host range, serological relationship, electron microscopy, and sequence analysis of the CP region, the virus was identified as a strain of TSV. To our knowledge, this is the first report of natural occurrence of TSV on cucumber and gherkin in India.

References: (1). A. I. Bhat et al. Arch. Virol. 147:651, 2002. (2). B. J. C. Cornelissen et al. Nucleic Acids Res.12:2427, 1984.
Occurrence of Rust Disease Caused by Puccinia lagenophorae on Cineraria in the Americas
Authors: Hernández J. R. , Daughtrey M. , Jens J.
Published: May 2007

Cineraria (Pericallis × hybrida B. Nord.), sometimes referred to as Senecio cruentus (Masson ex L'Hér.) DC., Asteraceae, is native to the Canary Islands. This important ornamental plant is cultivated worldwide and is of significant economic importance in the United States as a flowering potted plant. In February 2002, rust pustules were observed on cineraria plants cultivated in a greenhouse in Suffolk County, New York. The rust was identified as Puccinia lagenophorae Cooke (2). Aecioid sori were up to 1 mm in diameter and densely clustered, yellowish, and amphigenous but mainly hypophyllous on swollen, rounded, infected areas. The peridium is cupulate, lacerate, and composed of colorless cells measuring 10.5 to 20 × 18 to 33 μm that are verrucose on the outer surface and finely verrucose on the inner surface. Spores are sessile, 12 to 18 × 10.5 to 17 μm, yellowish, minutely verrucose with conspicuous, loosely attached globules, and in long chains in fresh material. Telia were not observed. Signs and symptoms were reproduced by rubbing healthy leaves of Pericallis × hybrida with a rust-infected leaf of Pericallis × hybrida bearing aecia sori. Plants were enclosed in a plastic bag for 18 h and held at 21°C. Aecioid sori developed within 10 days. Voucher specimens have been deposited in the U.S. National Fungus Collection (BPI 841952 and 841953). Common groundsel (S. vulgaris L.) infected by P. lagenophorae was observed outside the greenhouse in which the infected cineraria were discovered (W. L. Bruckart and A. Senesac, unpublished), and we postulated that the cineraria in the greenhouse might have been infected by spores from those infected weeds. Cross-infectivity was tested by rubbing leaves of groundsel on which aecia sori of P. lagenophorae were present on five leaves on each of three healthy cineraria plants. Incubation conditions were the same as described above. Aecioid sori developed 10 days after inoculation on four leaves of one plant. The control plants remained healthy. The inoculation was repeated on two plants and aecia sori developed on leaves of both plants. To our knowledge, this is the first report of P. lagenophorae on cineraria in the Americas. P. lagenophorae is autoecious, native to Australia and New Zealand, and has approximately 60 known host species (2). Recently, it was reported in California on common groundsel (3) and English daisy (Bellis perennis L.) (1).

References: (1) S. T. Koike and M. Scholler. Plant Dis. 85:562, 2001. (2) M. Scholler. Sydowia 49:177. 1997. (3) M. Scholler and S. T. Koike. Plant Dis. 85:335, 2001.
First Report of Plasmopara petroselini on Parsley in Belgium
Authors: Crepel C. , Inghelbrecht S.
Published: May 2007

Plasmopara petroselini (Oomycetes) was identified on parsley (Petroselinum crispum subsp. crispum cv.Petra) (Apiaceae) in Belgium during the winters of 2001 and 2002. The fungus was present in numerous fields, especially on parsley grown in plastic tunnels. Losses were sometimes dramatic and similar to disease problems in France and Switzerland where 80 and 50 ha, respectively, were found infected (1). Initial symptoms consisted of white spots on the upper leaf surface. As the disease progressed, the spots enlarged, became angular, and turned yellow. At the location of leaf spots, white-to-grayish white mycelium developed on the lower surface of the leaves. Eventually the leaves and leaf stalks rotted. The pathogen was identified at the Centraalbureau voor Schimmelcultures (CBS) (Utrecht, the Netherlands) as the downy mildew organism P. petroselini (= P. umbelliferarum pro parte = P. nivea pro parte = P. crustosa), based on morphological characteristics. Sporangia were papillate, lemon-shaped, almost hyaline, and 9 to 20 μm long, and produced on tree-like sporangiophores (100 to 420 × 6 to 8.5 μm) that were monopodially branched at approximately right angles. The sporangiophores usually bear three sterigma (4 to 19 × 2 to 3 μm) that narrow toward the tip (2). Prophylactic actions are the primary method to prevent the disease. Fungicides based on propamocarb can be used as a curative control method. To our knowledge, this is the first report of P. petroselini on parsley in Belgium.

References: (1) E. Béliard and J. Thibault. Phytoma 554:2, 2002. (2) M. Brandenburger. Page 451 in: Parastische Pilze an Gefässpflanzen in Europa. Fischer Verlag, Stuttgart, Germany, 1985.
Occurrence of Seed Coat Mottling in Soybean Plants Inoculated with Bean pod mottle virus and Soybean mosaic virus
Authors: Hobbs H. A. , Hartman G. L. , Wang Y. , Hill C. B. , Bernard R. L. , Pedersen W. L. , Domier L. L.
Published: May 2007

Soybean seed coat mottling often has been a problematic symptom for soybean growers and the soybean industry. The percentages of seed in eight soybean lines with seed coat mottling were evaluated at harvest after inoculating plants during the growing season with Bean pod mottle virus (BPMV), Soybean mosaic virus (SMV), and both viruses inside an insect-proof cage in the field. Results from experiments conducted over 2 years indicated that plants infected with BPMV and SMV, alone or in combination, produced seed coat mottling, whereas noninoculated plants produced little or no mottled seed. BPMV and SMV inoculated on the same plants did not always result in higher percentages of mottled seed compared with BPMV or SMV alone. There was significant virus, line, and virus-line interaction for seed coat mottling. The non-seed-coat-mottling gene (Im) in Williams isoline L77-5632 provided limited, if any, protection against mottling caused by SMV and none against BPMV. The Peanut mottle virus resistance gene Rpv1 in Williams isoline L85-2308 did not give any protection against mottling caused by SMV, whereas the SMV resistance gene Rsv1 in Williams isoline L78-379 and the resistance gene or genes in the small-seeded line L97-946 gave high levels of protection against mottling caused by SMV. The correlations (r = 0.77 for year 2000 and r = 0.89 for year 2001) between virus infection of the parent plant and seed coat mottling were significant (P = 0.01), indicating that virus infection of plants caused seed coat mottling.
G7H, a New Soybean mosaic virus Strain: Its Virulence and Nucleotide Sequence of CI Gene
Authors: Kim Yul-Ho , Kim Ok-Sun , Lee Bong-Choon , Moon Jung-Kyung , Lee Sang-Chul , Lee Jang-Yong
Published: May 2007

A new Soybean mosaic virus (SMV) strain was isolated in Korea and designated as G7H. Its virulence on eight differentials and 42 Korean soybean cultivars was compared with existing SMV strains. G7H caused the same symptoms as G7 did on the eight differential cultivars. However, it caused different symptoms on the G7-immune Korean soybean cultivars; G7H caused necrosis in Suwon 97 (Hwangkeumkong) and Suwon 181 (Daewonkong), and a mosaic symptom in Miryang 41 (Duyoukong), while G7 caused only local lesions on those varieties. The nucleotide sequence of the cylindrical inclusion region of G7H was determined and compared with other SMV strains. G7H shared 96.3 and 91.3% nucleotide similarities with G2 and G7, respectively; whereas G7 shared 95.6% nucleotide similarity with G5H.
First Report of Tobacco streak virus Infecting Safflower (Carthamus tinctorius) in Maharashtra, India
Authors: Rao S. Chander , Rao R. D. V. J. Prasada , Kumar V. Manoj , Raman Divya S. , Raoof M. A. , Prasad R. D.
Published: May 2007

Safflower, Carthamus tinctorius L. (Asteraceae), is extensively cultivated in India, China, and other parts of Asia for edible oil, dyeing agent, and its medicinal value. In 2003, safflower entry (NARI-6) in the All-India Coordinated Research Project on Oilseeds (Safflower) grown in the experimental fields of M/s Syngenta India Ltd., Aurangabad (Maharashtra State, India) exhibited symptoms of veinal and leaf necrosis, necrotic streaks on the stem, necrosis of the terminal bud, and ultimately plant death. The disease was attributed to Tobacco streak virus (TSV) because sunflower growing adjacent to safflower showed similar symptoms caused by TSV (1). Mechanical inoculations of sap from symptomatic safflower leaves caused typical symptoms of TSV (local, irregular, necrotic rings, veinal necrosis, and systemic veinal necrosis) on Vigna unguiculata (L.) Walp. cv. C-152 and Phaseolus vulgaris (L.) cv. Topcrop, and symptoms of local, necrotic lesions, veinal necrosis, and systemic necrosis of leaf and growing bud on Arachis hypogaea L. cv. JL-24. Sap-inoculated safflower cv. Manjeera showed chlorotic and necrotic local lesions followed by systemic leaf necrosis, leading to necrosis and death of the terminal bud. Safflower cvs. A-1, BIP-2, Co-1, and Bheema (10 plants of each cultivar) inoculated with sap from safflower plants showing typical TSV symptoms did not show any visible symptoms except stunting, but six to nine plants of each cultivar tested positive for TSV using enzyme-linked immunosorbent assay (ELISA) tests. In direct antigen coating-ELISA, the virus reacted positively with antiserum produced to an isolate of TSV from peanut (2) and to antiserum to TSV (ATCC-PVAS 276 for Datura stramonium), but did not react to peanut bud necrosis tospovirus antiserum. Examination of leaf extracts using leaf-dips and immunosorbent electron microscopy with the antiserum of TSV-peanut isolate showed isometric particles resembling those in the genus Ilarvirus. To our knowledge, this is the first report of an isolate of Tobacco streak virus infecting safflower.

References: (1) R. D. V. J. Prasada Rao et al. J. Oilseeds Res. 17:400, 2000. (2) A. S. Reddy et al. Plant Dis. 86:173, 2002.
First Report of Botryotinia Blight of Asiatic Hybrid Lily Caused by Botryotinia sphaerosperma in North America
Authors: Scheck H. J. , Fogle D. G. , Tidwell T. E.
Published: May 2007

In November 2002, a disease was observed on eight cultivars of Asiatic hybrid lilies (Lilium sp.) in two fields in Carpinteria, CA. The same disease was observed on greenhouse grown Asiatic hybrid lilies in Nipomo, CA in an adjacent county. ‘Monte Negro’ was the most severely affected. Symptoms consisted of necrotic leaf tips as well as 5- to 10-mm ellipsoidal necrotic spots on stems and the abaxial and adaxial leaf surfaces. Lesions were initially dark brown and water soaked, becoming lighter as they dried. Although leaf spot symptoms usually began at the leaf tip, eventually the entire leaf would become blighted. Disease symptoms were not observed on Oriental hybrid lilies in the same nurseries. A Botrytis sp. was consistently associated with the disease symptoms. In pure culture, the fungus matched the description of Botryotinia sphaerosperma (Gregory) Buchw. (anamorph Botrytis sphaerosperma (Gregory) Buchw.) (1). The fungus is distinguished by its large, spherical conidia that average 23 to 25 μm in diameter at maturity. The conidia are born in compact heads on unbranched conidiophores. Conidia and conidiophores are hyaline when young. At maturity, the conidia turn dark brown, whereas the conidiophores turn blackish brown. The fungus formed abundant sclerotia on potato dextrose agar when incubated at room temperature with 12 h per day of fluorescent lighting. The sclerotia were black, ovate to sphaeroidal, had a rough surface, and were 1.5 to 2.5 × 1 to 2.5 mm. Apothecia were not observed. Pathogenicity was tested on 12 Asiatic hybrid and 12 Oriental hybrid lilies. Inoculum consisting of mycelial fragments and conidia (1 × 105 conidia per ml) was produced on lily leaf agar (500 ml of H2O, 7.5 g of agar, and 25 g of healthy, macerated lily leaves). Plants were inoculated by rubbing leaves and stems with the spore and mycelial fragment suspension using cotton swabs. Plants were maintained in a greenhouse at 25°C. After 7 days, characteristic lesions were observed on the leaves and stems of Asiatic hybrid and Oriental hybrid lilies, from which the same Botrytis sp. was consistently isolated. Three control plants each of Asiatic hybrid and Oriental hybrid lilies treated with water as a check, remained symptomless. Although studies to determine potential fungicides for controlling this pathogen have not yet been undertaken, good sanitation, a lily-free period, and steam sterilization of beds should be considered in the management of this disease. In Europe, this fungus has been reported as a pathogen on Lilium regale (2). To our knowledge, this is the first report of this pathogen in North America. Herbarium specimens were submitted to the USDA APHIS mycology laboratory in Beltsville, MD (Accession No. BPI 842231). Cultures were also submitted to the American Type Culture Collection (MYA-2890).

References: (1) P. H. Gregory. Trans. Br. Mycol. Soc. 25:26, 1941. (2) G. L. Hennebert. Friesia 9:52, 1969.
First Report of Zucchini yellow mosaic virus in Cucumber in Poland
Authors: Pospieszny H. , Cajza M. , Plewa R.
Published: May 2007

In June 2002, mosaic and interveinal chlorosis were observed on two cucumber plants (Cucumis sativus) grown in one commercial greenhouse in the western region of Poland. Electron microscopic examination of leaf-dip preparations from infected plants showed flexuous filamentous virus particles typical of potyviruses (720 to 750 nm long). Chenopodium amaranticolor, Chenopodium quinoa, Citrullus lanatus, C. melo, C. sativus, Cucurbita maxima, Cucurbita pepo, Cucurbita pepo cv. Giromontiina, Cucurbita pepo cv. Patissoniana, Nicotiana benthamiana, and N. tabacum were mechanically inoculated with sap from symptomatic cucumber leaves. The virus caused local chlorotic lesions on Chenopodium amaranticolor and Chenopodium quinoa and systemic infection in all tested cucurbits but it did not infect tobacco plants. Reverse transcription-polymerase chain reaction (RT-PCR) amplification of the 3′ end of the genomic RNA was done by using P9502 as a downstream primer and degenerate CPUP as an upstream primer to amplify a highly conserved region of the potyviral coat protein (1). The PCR products were directly sequenced with the CEQ DTCS dye terminator cycle sequencing kit (Beckman Coulter, Inc., Fullerton, CA), and the analysis of dideoxy terminated fragments was conducted by capillary electrophoresis using a CEQ 2000 DNA Analysis System (Beckman Coulter, Inc.). The obtained 684 nt sequence (GenBank Accession No. AY347476) was almost identical with sequences of Zucchini yellow mosaic virus (ZYMV) isolates from Austria (GenBank Accession Nos. AJ420012-AJ420019 and AJ420027) and Hungary (GenBank Accession Nos. AJ459954 and AJ459955). The above suggested that the Polish isolate of ZYMV belonged to the Central European branch of the phylogenetic tree (2). To our knowledge, this is the first report of ZYMV in Poland.

References: (1) R. A. A. van der Vlugt et al. Phytopathology 89:148, 1999. (2) I. Tobias and L. Palkovics. Pest Manage. Sci. 59:493, 2003.
Yield Losses Associated with Virus-Infected Garlic Plants During Five Successive Years
Authors: Conci Vilma C. , Canavelli Ana , Lunello P. , Di Rienzo J. , Nome S. F. , Zumelzu G. , Italia Rusell
Published: May 2007

Virus-free garlic plants, when planted in the field, are quickly infected by viruses, but it is not known to what extent this affects the yield over successive crop cycles. The yield loss curve was studied for these plants during 5 years of tests in the field. Highly significant differences were detected in the weight and perimeter of bulbs in relation to the years of exposure to virus infection. An increase was observed in yield compared with chronically diseased plants of between 66 and 216% in weight and 13 and 37% in perimeter of bulbs in the first crop cycle and 49% in weight and 16% in perimeter in the fifth year. These results showed a gradual loss in yield until the third year, and subsequently the production values remained steady for the fourth and fifth years of testing but were still higher than those reached by chronically diseased plants.
Potential Primary Inoculum Sources of Bean pod mottle virus in Iowa
Authors: Krell Rayda K. , Pedigo Larry P. , Hill John H. , Rice Marlin E.
Published: May 2007

A survey of Bean pod mottle virus (BPMV) in Iowa counties was conducted and the virus was found throughout the state. A long-term monitoring study (1989 to 2002) of the main BPMV vector, the bean leaf beetle, Cerotoma trifurcata, indicated that, in 2002, populations reached the highest abundance recorded in 14 years. Three potential sources for an early season primary inoculum source were found: (i) soybean (Glycine max) seed, (ii) overwintered bean leaf beetles, and (iii) alternate BPMV host plants. Examination of 5,804 and 8,064 soybean seedlings of two cultivars yielded 0 and 3 seedlings, respectively, infected with BPMV. In a separate test, BPMV was detected in mottled and nonmottled soybean seed. Some mottled seed did not contain BPMV, indicating that soybean seed coat mottling is an unreliable indicator for presence of the virus in seed. Of 194 naturally overwintered bean leaf beetles, only 1 transmitted BPMV to soybean. BPMV was detected serologically only in 1 alternate host, Desmodium canadense, out of 23 naturally occurring plant species collected from the field. The three inoculum sources discovered in Iowa in this study could be important primary sources when vector populations are high and indicate starting points for future epidemiological investigations.
Characterization of Colletotrichum graminicola Isolates Resistant to Strobilurin-Related QoI Fungicides
Authors: Avila-Adame Cruz , Olaya Gilberto , Köller Wolfram
Published: May 2007

Isolates of Colletotrichum graminicola were collected from annual bluegrass or bent grass turf in Japan and the United States, and their sensitivities to QoI fungicides (QoIs) as well as their cytochrome b sequences were characterized. Five isolates sampled from turf treated repeatedly with azoxystrobin were highly QoI resistant under both in vivo and in vitro test conditions. The nucleotide sequences of a large cytochrome b gene segment involving the binding site of QoIs were fully homologous for all resistant isolates and contained the G143A target site mutation known to confer QoI resistance in other pathogens. QoI-sensitive isolates collected prior to treatments with QoIs were more diverse with regard to their cytochrome b gene sequences and their phenotype responses to QoIs. All wild-type isolates retained a glycine in position 143 of cytochrome b. Three of the four QoI-sensitive isolates were, in addition, distinguished by leucines in positions 95, 130, and 141, which were exchanged to threonine in all resistant but also in one of the sensitive isolates. In addition to a more pronounced divergence of cytochrome b sequences, the sensitive wild-type isolates also were diverse with regard to the induction of alternative respiration in response to QoI action, as indicated by comparisons of QoI sensitivities displayed in the absence or presence of the alternative oxidase inhibitor salicylhydroxamic acid. These different phenotype responses expressed under in vitro test conditions had no or only a slight impact on anthracnose control in protective applications of azoxystrobin. Isolate responses in vitro were very similar for trifloxystrobin, indicating cross-resistance among the class of QoIs. Our results imply that C. graminicola falls into the class of pathogens with a potential for rapid selection of highly QoI-resistant phenotypes. Frequent monitoring of population sensitivities will be required to determine the status of population responses toward practical QoI resistance.