bluuebunny/crossref_metadata_2025 huggingface dataset:
First Report and Partial Molecular Characterization of a New Begomovirus Associated with Pigeon Pea in Puerto Rico
Authors: Rodriguez R. L. , Hong S. , Maxwell D. P.
Published: May 2007

Pigeon pea (Cajanus cajan (L.) Millsp.) is an important edible legume crop in Puerto Rico. In late fall 1997, symptoms of a golden mosaic virus were observed in a pigeon pea planting in the municipality of Villalba. The symptoms resembled those incited by the Rhynchosia mosaic virus, a whitefly-transmitted virus, in pigeon pea (1). Tests with the 3F7 antigeminivirus antibody from Agdia (Elkhart, IN) confirmed the presence of a begomovirus in these symptomatic pigeon peas. Extraction of DNA from dried symptomatic foliar tissue was accomplished by the methods described in Rojas et al. (2), and subsequent viral DNA amplification was accomplished with the coat protein (CP) gene polymerase chain reaction primer pair AV494-AC1048 (3). A 550-bp fragment was cloned and sequenced (GenBank Accession No. AY028308). For sequence analysis, the BLAST program at the National Institutes of Health was used. The first match was 91% with the CP gene sequence (Accession No. AF070924) of a begomovirus from Clitoria falcata from Puerto Rico. The next three matches were approximately 86% with a begomovirus (accession no. AF058024) from Macroptilium lathyroides from Puerto Rico, Dicliptera yellow mottle virus (Accession No. AF139168) from Florida, and Tobacco apical stunt virus (Accession No. AF076855) from Mexico. On the basis of sequence analysis of this conserved region of the CP gene, it is concluded that the virus described in this report is a new virus, and thus named Pigeon pea golden mosaic virus. The only sequence for a begomovirus from a Rhynchosia sp. in GenBank is Rhynchosia golden mosaic virus from Honduras (accession no. AF239671). On the basis of sequence comparisons, the virus from pigeon pea is not an isolate of the Honduran Rhynchosia golden mosaic virus.

References: (1) J. Bird et al. 1975. Pages 3–25 in: Tropical Diseases of Legumes. J. Bird and K. Maramorosch, eds. Academic Press, NY. (2) M. R. Rojas et al. Plant Dis. 77:340, 1993. (3) S. D. Wyatt and J. K. Brown. Phytopathology. 86:1288, 1996.
First Report of Fusarium Wilt of Exacum affine Caused by Fusarium oxysporum
Authors: Elmer W. , O'Dowd E.
Published: May 2007

Wilting Persian violets (Exacum affine) were observed in a Connecticut retail outlet. Diseased stems developed a dark coloration at the nodes, while the foliage turned papery, whitish tan. The vascular tissue in affected stems was reddish brown and extended from the base of the stem upward in a unilateral pattern. Fusarium grew from the discolored stem tissue when placed on Komada's medium (2). Single spores were cultured on carnation leaf agar and identified as F. oxysporum (2). Koch's postulates were completed by growing 12 2-month-old seedlings of E. affine ‘Midget’ in potting mix amended with ground dried millet seed (2.0 g/liter of soil) that had been colonized for 2 weeks by the fungus. Symptoms appeared slowly after 8 weeks, and F. oxysporum was re-isolated from the vascular tissue. Plants grown in soil mix with sterile millet remained healthy. Similar tests at different times of the year produced the same results. Other tests examined host specificity with two new isolates on seedlings of Persian violet, carnation, lisianthus, and basil. Both isolates caused symptoms only on Persian violets. Although Haematonectria haematococca (synonym Nectria haematococca, anamorph F. solani) causes Nectria canker of Persian violet (1), this is the first report of F. oxysporum causing Fusarium wilt of Persian violet. We propose the formae specialis be F. oxysporum f. sp. exaci. An isolate has been deposited at the Fusarium Research Center at The Pennsylvania State University, University Park, under Accession No. O-2282.

References: (1) M. Daughtrey et al. Compendium of Flowering Potted Plant Diseases. American Phytopathological Society, St. Paul, MN, 1995. (2) Nelson et al. Fusarium species: An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, PA, 1983.
Xanthomonas Leaf Spot of Catnip: A New Disease Caused by a Pathovar of Xanthomonas campestris
Authors: Koike Steven T. , Azad Hamid R. , Cooksey Donald A.
Published: May 2007

Xanthomonas leaf spot is a new disease that has occurred on catnip (Nepeta cataria). Catnip is grown commercially in California for use as herbs, seasonings, and tea. This disease has developed recently on catnip transplants that are produced in enclosed greenhouses. Symptoms consist of small brown flecks that are visible from both sides of a leaf. The flecks later develop into larger, dark brown, angular leaf spots. Severe infection reduced the quality and marketability of the transplants. Xanthomonas campestris, as identified by biochemical, physiological, and molecular tests, was consistently isolated from symptomatic plants, and selected strains caused similar symptoms when inoculated onto catnip test plants. However, catnip strains failed to cause any symptoms when inoculated onto nine other plants in the Lamiaceae family and five other hosts of known X. campestris pathovars. Catnip plants showed no symptoms when inoculated with X. campestris pvs. campestris, carotae, and vesicatoria. Catnip also was not susceptible to the X. campestris pathogen isolated from lavender. This is the first report of a bacterial disease of catnip caused by a Xanthomonas pathogen, and the catnip strains may be a new and distinct pathovar of X. campestris.
First Report of Sclerotinia sclerotiorum on Gazania sp. Hybrid in Italy
Authors: Garibaldi A. , Minuto A. , Gilardi G. , Gullino M. L.
Published: May 2007

Gazania sp. hybrid is produced in pots in the Albenga Region of northern Italy for export to central and northern Europe. During fall 2000 to spring 2001, sudden wilt was observed in commercial plantings of this ornamental. Initial symptoms included stem necrosis at the soil level and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt followed by soft rot occurred within a few days on young plants after the first leaf symptoms. Necrotic tissues became covered with white mycelia that produced dark, spherical (2 to 6 mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from infected stem pieces of Gazania disinfested for 1 min in 1% NaOCl, plated on potato dextrose agar amended with streptomycin sulfate at 100 mg/liter. Pathogenicity of three fungal isolates was confirmed by inoculating 45- to 60-day-old plants grown in containers (14 cm diameter). Inoculum that consisted of wheat kernels infested with mycelium and sclerotia of each isolate was placed on the soil surface around the base of each plant. Noninoculated plants served as controls. All plants were maintained outdoors where temperatures ranged between 8 and 15°C. Inoculated plants developed symptoms of leaf yellowing, followed by wilt, within 7 to 10 days, while control plants remained symptomless. White mycelia and sclerotia developed on infected tissues, and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of wilt of Gazania sp. hybrid caused by S. sclerotiorum in Italy. A crown rot of Gazania caused by S. sclerotiorum has been reported from California in the United States(1).

Reference: (1) V. M. Muir and A. H. McCain. Calif. Plant Pathol. 16:1, 1973.
Evaluation of the Burkard Cyclonic Spore Sampler for Collection Efficiency of Ascospores
Authors: Larson Carrie , Francl Leonard J. , Friesen Timothy
Published: May 2007

The commercially available Burkard cyclonic sampler takes in air volumetrically, creates a vortex in an aluminum cylinder, and deposits particulates in an Eppendorf vial. Retention within the cylinder was determined for ascospores released by cultures of Sordaria fimicola and Gibberella zeae. Manufacturer's recommended amperage level and reduced power were tested, and a surfactant was applied to the cylinder wall. Under recommended power, an average of 78% of the S. fimicola ascospores were collected in the vial, while 22% lodged inside the cylinder. Conversely, only 25% of the G. zeae ascospores were collected in the vial, while 75% remained lodged inside the cylinder. Application of a surfactant to reduce the adherence of ascospores on the cylinder wall, instead resulted in 83% of the S. fimicola ascospores and 99.7% of the G. zeae ascospores deposited on the cylinder wall. When the power supply was decreased from 200 mA to 140 mA, the ratio of ascospores of G. zeae retained by the sampler remained nearly the same, indicating that the retention error was not a function of airflow rate within the tested power range. However, the total number of ascospores collected was significantly less under reduced power. A 90-A/h (12 V) battery supplied greater than 150 mA when connected to the Burkard for 4 days at temperatures between 22 and 28°C and could maintain current above 190 mA for 7 days with a 21-W solar panel. A 21-W solar panel charging a 90-A/h battery should maintain the amperage needed for the Burkard to maintain proper flow rate in most environments. The aluminum cylinder should be rinsed out thoroughly when collecting samples of fungal ascospores or any other particulates with the propensity to adhere to the cylinder wall.
Inheritance of Resistance to Celery mosaic virus in Celery
Authors: D'Antonio Vincent , Falk Bryce , Quiros Carlos F.
Published: May 2007

Screening of the Apium germ plasm collection for resistance to Celery mosaic virus (CeMV) revealed four resistant accessions: a celeriac, a feral celery line, and two wild celery species. The feral celery, which is genetically closest to cultivated celery, A. graveolens var. dulce, was used to generate backcross and F2 progenies to determine the inheritance of the resistance. Resistance was recessive and determined by a single locus named cmv. The simple inheritance of this trait will allow the development of celery lines resistant to CeMV.
Bermudagrass Dead Spot: A New Disease of Bermudagrass Caused by Ophiosphaerella agrostis
Authors: Krausz J. P. , White R. H. , Tisserat N. A. , Dernoeden P. H.
Published: May 2007

Hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) is widely used on golf course putting greens in the southern United States. In March and April 1998, circular patches of dead grass 2 to 10 cm in diameter were observed on a bermudagrass putting green in College Station, TX, that had been overseeded with rough bluegrass (Poa trivialis L.) the previous October. Rapid death and deterioration of the rough bluegrass within the spot revealed extensive foliar and crown necrosis and root decay of the remaining bermudagrass. Diseased bermudagrass leaves in the patch were reddish brown to tan. Dark ectotrophic hyphae were not found on the roots or stolons, but dark hyphae were observed within the affected root tissues. Numerous pseudothecia were embedded in necrotic leaf and stolon tissues. The characteristics of the pseudothecia and ascospores coincide with the description of Ophiosphaerella agrostis Dernoeden, Camara, O'Neil, van Berkum, and Palm (1,2). This fungus was consistently isolated from stolons and roots, and single-ascospore isolates were obtained from pseudothecia. Inoculum was prepared by transferring fungal mycelium from a single-spore isolate grown in potato dextrose agar (PDA) to a moistened, autoclaved mixture of rice hulls (Oryza sativa L.) and milled rice (2:1, vol/vol) for 28 days at 24°C. ‘FloraDwarf’ bermudagrass was grown from stolons in 15-cm-diameter pots containing a mixture of sand, peat moss, and perlite (8:3:1, vol/vol). The bermudagrass was maintained at a height of 1 to 1.5 cm for ≈ 1 month. Plants were inoculated by forming a hole that was 0.8 cm in diameter and 7 cm deep in the center of the pot, using a rod and filling the hole with inoculum. Control pots received the same treatment, except uninoculated rice hull-milled rice mixture was used. The treatments were replicated three times, and the experiment was performed twice. The pots were maintained in a greenhouse for 6 weeks. In all inoculated pots, patches of dead bermudagrass 6 to 10 cm in diameter developed. Roots, stolons, and leaves were necrotic, and pseudothecia were abundant in stolon and leaf sheath tissues. O. agrostis was consistently reisolated from infected root and stolon tissues. All isolates produced colonies identical in appearance to the culture used for inoculation. To our knowledge, this is the first report that O. agrostis is pathogenic to hybrid bermudagrass.

References: (1) M. P. S. Camara et al. Mycologia 92:317, 2000. (2) P. H. Dernoeden et al. Plant Dis. 83:397, 1999.
First Report of Tomato yellow leaf curl virus in Mississippi
Authors: Ingram D. M. , Henn A.
Published: May 2007

Tomato yellow leaf curl virus (TYLCV) is a begomovirus (family Geminiviridae) that causes severe chlorosis, stunting, and cupping of leaves in tomato (Lycopersicon esculentum) throughout the world. The disease was first reported in the United States in Florida in 1997 (2). In 2000, TYLCV was confirmed as the cause of severe chlorosis, stunting, and cupping of leaves in tomato in Louisiana (3). In January of 2001, mild symptoms consistent with TYLCV were observed in a greenhouse-tomato production operation in east-central Mississippi. Whiteflies (Bremisia tabaci) were present in the greenhouse during the previous month, but in relatively low numbers. Symptom severity slightly increased over time with chlorosis in the terminal, reduction in terminal leaf size, and upward cupping of leaves observed. Approximately 4% of plants in the greenhouse developed symptoms. Yield reductions are thought to be negligible since the tomato plants harbored most fruit for that growing season. Terminal growth was halted, and no additional flower production was observed. No symptoms were observed on mature fruit; however, fruit set after leaf symptoms developed remained stunted. A representative sample of symptomatic tissue was submitted to an independent lab (Agdia, Inc., Elkhart, IN), screened for whitefly-transmitted geminiviruses, and the results were positive. Additional symptomatic tomato tissue was submitted to the University Diagnostics Lab, University of Florida, Gainesville, and was observed for viral inclusion bodies. This test was positive for TYLCV based on morphology of virus particles located in the nucleus of tomato cells (1). Total DNA was extracted from the symptomatic plants for polymerase chain reaction (PCR) assay (2). Results from the PCR assay indicated the presence of TYLCV in symptomatic tomato tissue. The strain of the virus was not determined. To our knowledge, this is the first report of TYLCV in Mississippi.

References: (1) B. Pico et al. Sci. Hortic. 67:151, 1996. (2) J. E. Polston et al. Plant Dis. 83:984, 1999. (3) R. A. Valderde et al. Plant Dis. 85:230, 2001.
First Report of Tomato spotted wilt virus on Soybean in Iran
Authors: Golnaraghi A. R. , Shahraeen N. , Pourrahim R. , Ghorbani Sh. , Farzadfar Sh.
Published: May 2007

During the summers of 1999 and 2000, 3,110 soybean (Glycine max) leaf samples were randomly collected from soybean fields in the Ardebil, Goletan, Khuzestan, Lorestan, and Mazandaran provinces of Iran. Tomato spotted wilt virus (TSWV) was detected in leaf samples by TSWV-specific polyclonal antibody (As-0526 and As-0580, DSMZ, Braunschweig, Germany) in double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Mechanical inoculation of 26 plant species (10 plants per species) and cultivars with extracts of positive leaf samples produced necrotic local lesions in Beta vulgaris, Chenopodium quinoa, C. amaranticolor, Gomphrena globosa, Phaseolus vulgaris cv. Talash, Vicia faba, and Vigna unguiculata cv. Mashad; produced systemic chlorosis followed by necrosis in Datura stramonium, D. metel, Nicotiana rustica, N. tabacum cv. Samsun, N. glutinosa, N. bentamiana, and Glycine max cv. Hill; and produced chlorosis, stunting, and bud necrosis in Arachis hypogaea (peanut). Plants developing these symptoms following mechanical inoculation with extracts from original soybean leaves were positive in ELISA for TSWV. ELISA results indicate that the overall incidence of TSWV on soybean in the five provinces was 5.4%. TSWV has been reported in potato (2) and tomato (1) from Iran, but to our knowledge, this is the first report of the occurrence of TSWV on soybean in Iran.

References: (1) K. Bananej et al. Iran. J. Plant Pathol. 34:30, 1998. (2) R. Pourrahim et al. Plant Dis. 85:442, 2001.
Natural Infection of Vicia faba by Bidens mottle virus in Florida
Authors: Baker C. A. , Raid R. N. , Scully B. T.
Published: May 2007

In a study to evaluate the potential of Vicia faba (faba bean) as a cover and forage crop for Florida, 60 accessions of faba bean with diverse genetic backgrounds and geographic origins were acquired from the USDA Germplasm Repository in Pullman, WA. The beans were grown south of Lake Okeechobee in Belle Glade, FL, from December 2000 to April 2001. Reddish-brown elliptical lesions first appeared on the leaflets of two of the faba bean plants 10 to 12 weeks after planting. Within 2 weeks of initial symptoms, a mosaic pattern was expressed on the newly emergent leaves of the same plants. After disease expression, new pods aborted, while developing pods became stunted, distorted, and blistered. Potyvirus cylindrical inclusions (CI) were found in leaf strips (1) of the original plants. Viral symptoms were expressed in manually inoculated plants of Chenopodium amaraticolor, C. quinoa, Lactuca sativa, Nicotiana benthamiana, Petunia × hybrida, Verbena × hybrida, Vicia faba, and Zinnia elegans. Inoculated species of Phaseolus and Pisum were not infected. The virus causing the disease was identified as Bidens mottle virus (2) based on host range, characteristic CI in Z. elegans, and homologous lines of precipitation in SDS-immunodiffusion using antiserum to Bidens mottle and a known antigen. Both the primary host of this virus Bidens mottle virus and its aphid vectors are ubiquitous throughout Florida. To our knowledge, this is the first report of Bidens mottle virus infecting a member of the Leguminosae.

References: (1) R. G. Christie and J. R. Edwardson. Light and Electron Microscopy of Plant Virus. Monogr. 9, IFAS, University of Florida, 1994. (2) D. E. Purcifull et al. Bidens mottle virus. Descriptions of Plant Viruses. No. 161. CMI/AAB, Surrey, England, 1976.
Extreme Susceptibility of Primosole Mandarin to Alternaria Fruit Rot in Italy
Authors: Bella P. , Rosa R. La , Catara V. , Polizzi G.
Published: May 2007

Primosole mandarin is a promising mandarin-like hybrid of Satsuma Miho and Carvalhais mandarin that ripens very early, at the beginning of October, in southern Italy (2). During August and September 1999 and 2000 in Sicily, widespread fruit rot, affecting from 80 to 95% of the total production, was observed in a 4-year-old Primosole mandarin orchard. The fruits developed color prematurely and light brown-to-black discoloration of the rind at the stylar end. Internal symptoms consisted of a black rot of the fruit core. Sometimes the exterior of the fruits appeared healthy. No premature fruit drop was observed, and infected fruits became mummified and remained attached on the trees. Alternaria citri Ellis & N. Pierce in N. Pierce was consistently isolated from infected tissues, and the identification of the fungus was based on morphological characteristics of the conidia (1). Pathogenicity tests of single-spore isolates were carried out on surface-sterilized Primosole fruits and were repeated twice. Either a conidial suspension (2 × 104 conidia per ml) was injected into the core of fruits, or fruits were pricked at the stylar end near or through growth cracks in poorly formed navels, and the conidial suspension was placed on the wound. Thirty fruits were used per treatment, and thirty noninoculated fruits were used for controls. Following inoculation, the fruits were placed in plastic bags and kept at 30°C for 15 days. No external symptoms were observed on any of the fruits, but when cut in half, decay of the core was observed in all inoculated fruits. A. citri was reisolated from inoculated fruits, fulfilling Koch's postulates. No symptoms were observed on fruits used as controls. We believe that infection is facilitated by growth cracks at the stylar end and the sensitivity to sunburn of Primosole mandarin. To our knowledge, this is the first report of the extreme susceptibility of Primosole mandarin to Alternaria fruit rot.

References: (1) G. E. Brown and J. W. Eckert. Postharvest fungal diseases. Page 37 in: Compendium of Citrus Diseases, 2nd ed. L. W. Timmer, S. M. Garnsey, and J. H. Graham, eds. The American Phytopathological Society, St. Paul, MN, 2000. (2) E. Tribulato and G. La Rosa. Italus Hortus 1:21, 1993.
First Report of the Occurrence of Fusarium oxysporum f. sp. niveum Race 2 in Commercial Watermelon Production Areas of Maryland and Delaware
Authors: Zhou X. G. , Everts K. L.
Published: May 2007

Resistance to race 1 of Fusarium oxysporum f. sp. niveum (E.F. Sm.) W.C. Snyder & H.N. Hans) is the most widely used tool for management of Fusarium wilt of watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai). However, this resistance is ineffective against the more aggressive F. oxysporum f. sp. niveum race 2. Race 2 was first identified in Israel in 1973 (2) and was subsequently reported in Texas (1981), Oklahoma (1988), and Florida (1989) (1). From July through September 2000 in Maryland and Delaware, 123 isolates of F. oxysporum f. sp. niveum were collected from wilted plants or plants with vascular discoloration from commercial production fields with moderate to severe wilt severity. Race determination was performed in the greenhouse on five race-differential cultivars. Differential cvs. Sugar Baby, Crimson Sweet, Charleston Gray, Allsweet, and Dixielee range from susceptible to highly resistant (in the order listed) to race 1, but all are susceptible to race 2. Seeds were planted in pots containing pasteurized vermiculite and peat moss (2:3 mixture) growth medium infested with 1 × 105 conidia per g of growth medium. Conidia were harvested from 5- to 6-day-old cultures of F. oxysporum f. sp. niveum grown in a liquid mineral salts medium (2). Control pots were treated with water or diluted liquid medium. Pots were maintained in a greenhouse at 19 to 28°C. Three replicate pots containing seven plants each were used for each isolate-cultivar combination. Race 0 obtained from B. D. Bruton (USDA-ARS, Lane, OK), and races 1 and 2 obtained from the American Type Culture Collection (Manassas, VA) were included in the tests for comparative purposes. Eleven isolates from Maryland and three isolates from Delaware consistently caused 60 to 100% wilt or mortality of all cultivars, with a mean of more than 75% wilt. Percent wilt of cvs. Sugar Baby and Dixielee to races 0, 1, and 2, and the 14 isolates from Maryland and Delaware was 78, 76, 100, and 95 to 100% and 0, 14, 59, and 63 to 93%, respectively. All control plants remained healthy. In each of the three replicated tests, these 14 isolates caused an equal or greater incidence of wilt as the reference race 2 isolate, and cvs. Dixielee and Allsweet were susceptible to these isolates. Therefore, these isolates were identified as F. oxysporum f. sp. niveum race 2. This is the first report of F. oxsporum f. sp. niveum race 2 occurring in Maryland and Delaware.

References: (1) R. D. Martyn and B. D. Bruton. HortScience 24:696, 1989. (2) D. Netzer. Phytoparasitica 4:131, 1976.
Premature Fruit Drop in Saw Palmettos Caused by Colletotrichum gloeosporioides
Authors: Carrington M. E. , Roberts P. D. , Urs N. V. R. R. , McGovern R. J. , Seijo T. E. , Mullahey J. J.
Published: May 2007

Saw palmetto (Serenoa repens) is a palm species that grows naturally in the southeastern coastal plain of the United States and is most abundant in Florida. Extracts from saw palmetto fruit are sold worldwide in pharmaceutical and dietary supplements in a market valued at $2 billion per year. Lesions on blossoms and fruit and premature fruit drop were first observed in 1996. In 1997, premature fruit drop resulted in 100% loss of fruit in saw palmetto in central and south Florida. In 1998, fruit loss was 8 to 59%. A fungus was consistently isolated from diseased saw palmetto spadices and fruit and identified as Colletotrichum gloeosporioides based on morphological, immunological, and genetic characteristics. Inoculation of spadices of container-produced saw palmettos with C. gloeosporioides resulted in similar disease symptoms and subsequent reisolation of the causal agent. The cross-infection potential of isolates was demonstrated by infection of other hosts. This is the first report of C. gloeosporioides causing disease on saw palmetto.
Characterization of Colletotrichum gloeosporioides Isolates from Ornamental Lupines in Connecticut
Authors: Elmer Wade H. , Yang Huaan A. , Sweetingham Mark W.
Published: May 2007

Twenty-six isolates of Colletotrichum gloeosporioides were isolated from diseased ornamental lupines (Lupinus spp. ‘Russell Hybrids’) in seven different nurseries in Connecticut from 1996 to 1998. Three isolates from New Hampshire, New York, and Utah were also included. All isolates identified were pathogenic on lupine and vegetatively compatible with each other. Representative isolates were compared to lupine isolates from Quebec, Canada and France (COL-1 group), and from Australia and France (COL-2 group). Both groups are responsible for causing anthracnose of ornamental and forage Lupinus spp. in these countries. The Connecticut isolates were vegetatively compatible with the isolates in the COL-2 group and had random amplified polymorphic DNA profiles consistent with isolates in the COL-2 group. Isolates in the COL-1 group were vegetatively compatible only with each other and had random amplified polymorphic DNA profiles that differed from the COL-2 group. Isolates in both COL-1 and COL-2 were sensitive to both benomyl and thiobendazole, but the COL-1 group could be distinguished as slightly more tolerant than the COL-2 group and the Connecticut isolates. These assays provided persuasive evidence that the isolates from Connecticut belong to COL-2 group. The introduction of this homogenous pathogen population in Connecticut is likely due to the importation of infested seeds.
First Report of Cactus virus X on Hylocereus undatus (Cactaceae) in Taiwan
Authors: Liou M. R. , Hung C. L. , Liou R. F.
Published: May 2007

Hylocereus undatus Britt. & Rose (Cactaceae), commonly known as pitaya, produces edible fruits with red thorny peel and sweet white pulp containing numerous small soft seeds. In recent years, this fruit crop has become increasingly important in Taiwan. During a survey of diseases of pitaya, some plants were found with systemic mild mottling on the stems. A virus was mechanically transmitted that caused necrotic local lesions on Chenopodium amaranticolor and chlorotic lesions on C. quinoa. This virus also caused necrotic lesions with chlorotic halos on Gomphrena globosa and small chlorotic spots followed by systemic infection in Celosia argentea. Back inoculation from C. quinoa by sap transmission caused mild mottling on pitaya similar to that observed on the naturally infected plants and thus confirmed that the agent was the cause of the mottle symptom. Electron microscopic examination of negatively stained extracts from diseased plants revealed a flexuous rod-shaped virus with a length of 480 to 520 nm. Purified viral particles contained a single major protein of approximately 26 KDa as estimated by SDS polyacrylamide gel electrophoresis. In immunodiffusion tests, this virus reacted with antiserum to Cactus X virus (CVX) (ATCC #PVAS245), but did not react with antisera to Bamboo mosaic or Papaya mosaic viruses. These results establish the identity of the virus causing mottle disease on H. undatus as a strain of CVX.
Melampsora Leaf Rust of Willow Causing a Stem Canker in Minnesota
Authors: Ostry M. E. , Anderson N. A.
Published: May 2007

In June 2000, during a routine examination of native willow (Salix sp.) growing in northwestern Minnesota, several plants were observed with multiple stem cankers. The cankers, some reaching 6 cm in length, were found on 1- to 3-year-old wood. Within the canker, the bark was blistered in several areas, exposing urediniospores averaging 15 × 24 μm. Although all North American willow leaf rusts are now included in the collective species Melampsora epitea, the spores fit the description of M. paradoxa (syn. M. bigelowii) (1). While evidence of previous sporulating cankers was present on older wood, no symptoms of leaf rust were present on the foliage in the area. Similarly, evidence of overwintering of M. bigelowii on young willow stems has been reported in Michigan (2). Willow species and cultivars used in biomass plantings need to be screened for rust resistance to local rust populations as the presence of a leaf rust infecting stems could become damaging to cultivated willow. For this reason, revision of the willow rust species and determination of their distribution and host range should be undertaken.

References: (1) J. C. Arthur. 1962. Manual of the Rusts in United States and Canada, Hafner Publishing, New York. (2) J. R. Weir and E. E. Hubert. Phytopathology 8:55, 1918.
First Report of Pythium aphanidermatum Causing Crown and Stem Rot on Opuntia ficus-indica
Authors: Rodríguez-Alvarado G. , Fernández-Pavía S. P. , Landa-Hernández L.
Published: May 2007

Opuntia ficus-indica (L.) Mill. (prickly pear cactus) is grown in semiarid regions of Baja California Sur (BCS), Mexico for human consumption and forage. Most of the produce is sold at local markets as a vegetable; however, there is an increasing demand from international markets. O. ficus-indica is propagated using individual cladodes, which are planted with half of the cladode covered with soil. Collapsed plants were observed in a commercial orchard near La Paz, BCS, during March 2000, and in an experimental plot at CIBNOR during August 2000. Disease incidence was 12% in the orchard and 27% at CIBNOR. The initial symptoms were soft, dark brown lesions on the cladode at the soil line. As the disease advanced, the lesions progressed along the soil line and to the upper part of the cladode. In some plants the infection reached upward to the next cladode. Root rot was observed in those cladode areas that were already rotting. Depending of the advance of the rot in the base cladode and the size of the plants, larger plants collapsed more rapidly than smaller plants, but eventually all plants with rot lesions collapsed. The organism consistently isolated from diseased cladodes of several varieties of O. ficus-indica produced inflated sporangia, intercalary antheridia, and oospores described for Pythium aphanidermatum Edson (Fitzp.) (2). To isolate the pathogen, cladodes with lesions were washed with detergent and brush, rinsed with tap water, and then the epidermis was covered with 95% ethanol and the ethanol burned. The epidermis was peeled away from the edge of the lesion and 1 square cm sections were aseptically removed. Tissue sections were plated out on potato-dextrose agar (PDA) plates. Pathogenicity studies were made twice in a greenhouse on a total of 16 potted O. ficus-indica plants with only one cladode. Inoculum was obtained from colonies growing on V8 agar for 7 days producing abundant oospores. Thirty milliliters of an oospore suspension (240 oospores per ml) and V8 agar plugs containing mycelia and oospores were applied next to the crown of the Opuntia plants. Initial symptoms were observed 2 days after inoculation and were similar to those observed on field-grown plants. All inoculated plants were dead 5 to 10 days after inoculation. P. aphanidermatum was re-isolated from diseased cladodes. Water-inoculated plants remained healthy throughout the experiments. P. aphanidermatum has been reported causing root rot in Opuntia sp. (1). This is the first report of P. aphanidermatum on O. ficus-indica.

References: (1) S. A. Alfieri Jr. et al. Fl. Dept. Agric. Cons. Serv. Div. Plant Ind. Bull. 11 (rev.), 1984. (2) A. J. Van der Plaats-Niterink. Monograph of the genus Pythium. Studies Mycol. 21:1, 1981
Isolation and Identification of Fusarium solani f. sp. glycines from Soil on Modified Nash and Snyder's Medium
Authors: Cho J. H. , Rupe J. C. , Cummings M. S. , Gbur E. E.
Published: May 2007

Modified Nash and Snyder's medium (MNSM) has been used to study soil populations of the fungus Fusarium solani f. sp. glycines, the causal agent of sudden death syndrome (SDS) of soybean. However, no studies have been conducted to confirm the accuracy of this technique in enumerating the SDS pathogen. To determine what portion of the colonies enumerated on MNSM are the SDS pathogen, 282 isolates resembling F. solani f. sp. glycines were collected from soil of two fields with a history of SDS in Arkansas using a soil dilution method with MNSM. The colony morphology of these isolates was compared on MNSM and on potato dextrose agar (PDA). Of these isolates, 112 were tested for pathogenicity on soybean in the greenhouse. In addition to fungi that produced colonies typical of F. solani f. sp. glycines on MNSM, 5 isolates each of four common colony types on MNSM were collected from each field for a total of 40 isolates. These isolates were compared to F. solani f. sp. glycines for colony morphology on PDA and for pathogenicity. Isolates that had colonies on MNSM that resembled F. solani f. sp. glycines had colony morphologies on PDA similar to this pathogen and produced SDS-like foliar symptoms in greenhouse inoculations of soybean. There was a significant quadratic relationship between foliar symptom severity and plant fresh weight. None of the other isolates tested resembled F. solani f. sp. glycines on either MNSM or PDA or produced SDS-foliar symptoms in greenhouse inoculations. These non-SDS isolates were F. solani, F. merismoides, a Pythium sp., and a Paecilomyces sp. All of these isolates produced some root rot, but significantly less than the F. solani f. sp. glycines reference isolate. The results of this study established that soil populations of F. solani f. sp. glycines can be accurately enumerated using MNSM. It should be noted that, on both MNSM and PDA, F. solani f. sp. glycines can resemble some isolates of F. solani f. sp. phaseoli, so pathogenicity tests of random isolates may be required to confirm the forma specialis especially in fields that have a history of both Glycines max and Phaseolus vulgaris.
Inheritance of Resistance to Aspergillus Ear Rot and Aflatoxin Production of Corn from CI2
Authors: Walker R. D. , White D. G.
Published: May 2007

This study determined the types and magnitude of gene action, estimated heritabilities, and predicted gain from selection for resistance to Aspergillus ear rot and aflatoxin production in the cross of resistant corn inbred CI2 to susceptible inbred B73 in 1998 and 1999. The warm, dry summer of 1998 favored aflatoxin production, whereas the conditions of 1999 did not. Resistance to ear rot was mainly controlled by additive gene action. Aflatoxin values were analyzed by individual years (environments) because of the highly significant generation × environment interaction. Resistance to aflatoxin production was mainly controlled by epistasis in 1998 and by additive gene action in 1999. Heritabilities for ear rot and aflatoxin production were higher in the F3generation than in the BCP1-selfed generation. In 1998, Spearman's correlation coefficients between Aspergillus ear rot ratings and aflatoxin values for the F3and the BCP1-selfed families were not significant (P > 0.05). In 1999, both were highly significant (P < 0.01), but low at 0.41 and 0.17 for the F3and BCP1-selfed generations, respectively. We found that CI2 is not an acceptable source of resistance due to lower heritabilities and disease resistance compared to other sources of resistance.
First Report of Ascochyta spp. on Soybean in South Africa
Authors: van Wyk P. S. , Herselman L. , Van der Linde E. J.
Published: May 2007

During February 2000 soybean fields over a wide area in South Africa were affected by a previously unreported disease. A typical target spot developed on leaves and many became blighted. Elongated dark brown to black lesions developed on the stems, often resulting in wilting of young shoots. Petioles and leaf axils were colonized, resulting in premature leaf drop. The most severe manifestation was on pedicels where infection suppressed podfill and plants remained green as ripening was delayed. Two distinct groups of isolates were obtained from lesions. In both groups an Ascochyta anamorph was present, while from some lesions collected in Kwazulu-Natal and Mpumalanga, a teliomorph (Mycosphaerella) was also present. Since dry beans are produced in these areas and M. phaseolorum is common on this crop, it was believed that the pathogen might have moved to soybean. In cross inoculations, both soybean and dry bean isolates were pathogenic to both hosts. However, M. phaseolorum isolates were more aggressive to both hosts than the Ascochyta sp. Morphologically the anamorphs of two types of isolates were indistinguishable. DNA was isolated from freeze dried mycelia using a modified version of the CTAB-method described by Graham et al. (1). The DNA concentration and purity were estimated by measuring absorbances at A260 and A280. Genetic difference between both isolates were determined using amplified fragment length polymorphism (AFLP) technique. The AFLP analysis was performed following the protocol described by Vos et al. (2) and the product manual supplied by Life Technologies Inc. (Gaithersburg, MD) with minor modifications. Five randomly selected primer pair combinations were tested for their ability to reveal polymorphisms between the isolates. The gel electrophoresis for AFLP products was as described by Vos et al. (2). AFLP gels were silver stained following the protocol described by silver sequence DNA sequencing system manual (Promega, Madison, WI). All five primer pairs revealed only polymorphisms between isolates. No corresponding bands between the two isolates were detected using these five primer pair combinations. It is concluded that both M. phaseolorum and an unidentified Ascochyta sp. were the cause of the epidemic. Ascochyta spp. have not previously been reported on soybean in South Africa.

References: (1) G. C. Graham et al. Biotechniques 16:48-50, 1994. (2) P. Vos et al. Nucleic Acids Res. 21:4407-4414, 1995.
First Occurrence of Puccinia lagenophorae Causing Rust Disease on Common Groundsel in North America
Authors: Scholler M. , Herbaria Arthur , Herbaria Kriebel , Koike S. T.
Published: May 2007

Common groundsel (Senecio vulgaris, Asteraceae) is native to Europe and is now a common weed mainly in disturbed habitats of almost worldwide distribution. In November 2000, groundsel plants growing adjacent to lettuce fields in California's coastal Salinas Valley (Monterey County) showed symptoms of rust. In a 0.2-ha survey area, 75% of the plants were infected. Examination of weeds growing in four residential blocks also uncovered infected groundsel. Densely clustered, orange aecia were observed on leaves and stems. Stems were swollen where aecia had formed. Blossom and fruit formation was not notably reduced, although some involucral bracts were infected. Aeciospores measured 14 to 18 μm × 12.5 to 15 μm (fresh material). Telia were not found. The pathogen was identified as Puccinia lagenophorae Cooke, a rust fungus that is native to Australia and New Zealand and infects plants of the subfamily Asteroideae (family Asteraceae) (3). P. lagenophorae is an autoecious species forming only repeating aecia (stage I) and telia (stage III). There are six other rusts of Senecio that occur in the United States (1) that readily form aecia but not telia on Senecio spp. When only aecia are observed on Senecio, which is typical for P. lagenophorae (2), the following features can be used to differentiate it from these other species: no pycnia (stage 0) are formed; aecia are formed repeatedly; systemic growth that results in deformation of the host, including formation of galls with dense clusters of aecia on the stem; poorly developed aecial peridium; and aeciospores small, measuring 12.5 to 18.5 μm × 10.0 to 16.0 μm (4). In addition, P. lagenophorae forms aecia even at the end of the year in northern temperate zones, whereas heteroecious species form aecia only in spring and early summer (2). This is the first record of P. lagenophorae in North America. Specimens were deposited in the Arthur Herbarium, Purdue University. Outside its native habitat, this fungus has been found in Europe, Africa, the Middle East, and South America. There are about 60 known host species of P. lagenophorae (3) including ornamentals such as Bellis perennis, Calendula officinalis, and Senecio cruentus. The pathogen may have been introduced to North America via land from South America through Central America, or by the importation of ornamentals that were either infected with rust or infested with diseased groundsel.

References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (2) M. Scholler. Regensb. Myk. Schr. 6:1, 1996. (3) M. Scholler. J. Plant Dis. Prot. 105:239, 1998. (4) I. Wilson et al. Trans. Brit. Mycol. Soc. 48:501, 1965.
First Report of Arceuthobium hondurense in Mexico
Authors: Mathiasen R. , Nickrent D. , Parks C. , Beatty J. , Sesnie S.
Published: May 2007

Honduran dwarf mistletoe (Arceuthobium hondurense Hawksw. & Wiens) is a rare dwarf mistletoe previously known only from Honduras (1,2). In March 2000 we collected a dwarf mistletoe from approximately 7 km west of San Cristobal de las Casas, Chiapas, Mexico near Route 190 (elevation 2,440 m), which was morphologically similar to A. hondurense (1). This population had initially been classified as A. nigrumHawksw. & Wiens (1). However, our morphological measurements and analysis of nuclear rDNA ITS sequences of A. hondurense plants from Honduras (GenBank No. AF325969) and the plants from Chiapas (AF325970) have confirmed that the Chiapan population is A. hondurense and not A. nigrum. An additional population of A. hondurense was discovered in Chiapas approximately 11 km west of Oxchuc near Route 186 (elevation 2160 m). Both of the Chiapan populations of A. hondurense were parasitizing Pinus tecunumanii(Schw.) Eguiluz et Perry. Specimens of A. hondurense from Chiapas were deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff. This is the first report of A. hondurense in Mexico and extends its known distribution from northwestern Honduras (3) by approximately 500 km. Although A. hondurense has not been observed in the pine forests of Guatemala, it is probable that it also occurs there (1).

References: (1) F. G. Hawksworth and D. Wiens. 1996. Dwarf Mistletoes: Biology, Pathology, and Systematics. USDA Agric. Handb. 709. (2) R. Mathiasen et al. Phytologia 36:211, 1998. (3) R. Mathiasen et al. Plant Dis. 84:372, 2000.
First Report of Sclerotinia sclerotiorum on Calendula officinalis in Italy
Authors: Garibaldi A. , Minuto A. , Gullino M. L.
Published: May 2007

Pot marigold (Calendula officinalis) has recently become popular as a potted ornamental plant in Italy. During the spring 1999, a sudden wilt of 120 day-old plants was observed in the Albenga region of Northern Italy, an area of intensive floriculture production. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Necrotic tissues resulted, covered with whitish mycelium that produced dark, spherical (2- to 6-mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from symptomatic stem sections surface disinfested 1 min in 1% NaOCl and plated on potato dextrose agar (PDA), amended with 100 ppm streptomycin sulfate. Pathogenicity of three isolates was confirmed by inoculating 90-day-old pot marigold plants grown in containers. Inoculum that consisted of wheat kernels infested with mycelium and sclerotia was placed on the soil surface around the base of previously wounded or non-wounded plants. Non-inoculated plants served as controls. All plants were kept outdoors where temperatures ranged between 8 and 16°C, under 50% shade and were maintained moist. Inoculated plants developed symptoms of leaf yellowing, followed by wilt within 7 days, while control plants remained symptomless. Sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. This is the first report of stem blight of C. officinalis caused by S. sclerotiorum in Europe. The disease was previously observed in the United States (1).

Reference: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.
First Report of Artichoke Downy Mildew Caused by Bremia lactucae in Argentina
Authors: Carranza M. , Larran S. , Alippi H.
Published: May 2007

In 1999, downy mildew was detected on artichoke (Cynara scolymus L.) plants from La Plata, Buenos Aires Province. The disease was observed on various commercial varieties. Symptoms were angular interveinal chlorotic spots less than 3 cm in size. These infected areas, although not confluent, covered a wide surface and caused early death of the leaves. On the undersides of these lesions, white-grayish sporulation was abundant, consisting of sporangiophores with dichotomous branches, widened in their peaks with 2 to 7 terminal sterigmata. Sporangia were ellipsoidal, hyaline and 14 to 30 × 12 to 25 μm in size. Oospores were not observed in leaf tissues. The pathogen was identified as Bremia lactucae Regel (1). Pathogenicity was confirmed with the inoculation of healthy artichoke plants. They were incubated in a humidity chamber at 10 to 15°C, and after 16 days chlorotic spots and downy mildew colonies developed. The presence of B. lactucae was confirmed by macro- and microscopic observation and Koch's postulates were fulfilled. This is the first report of downy mildew on artichoke in Argentina. Because it is widespread in the most important artichoke-growing area in Argentina (2), downy mildew should be considered in the cultural and sanitary management of the crop.

References: (1) P. Corda. Hypermedia Prot. Plantes, INRA, 1995. (2) A. Ricceti et al. Bol. Hortic. 4:4, 1996.