bluuebunny/crossref_metadata_2025_split huggingface dataset:
First Report of Powdery Mildew in Greenhouse-Grown Tomatoes in New Jersey
Authors: White J. F. , Johnston S. A. , Wang C.-L. , Chin C.-K. 
Published: May 2007

Powdery mildew of tomatoes caused by an Erysiphe sp. has been reported to occur in greenhouses in New York (2). In March and April of 1996, outbreaks of this disease were found in greenhouse-grown tomato plants of cv. PSR55809 at the Cook College campus in New Brunswick, NJ, and in cv. Match in commercial greenhouses in Burlington County, NJ. Identification of an Erysiphe sp. was made by comparative morphology of the conidial state since the perfect stage was not observed. Symptoms included development of patches of white mycelium predominantly on upper surfaces of older leaves followed by chlorosis of tissues colonized by the fungus. Microscopic examination of mycelium revealed the presence of typical Oidium conidiogenous cells and conidia. Conidiogenous cells were short and cylindrical and produce conidia in chains apically. Conidia were hyaline, cylindrical to ellipsoidal, and measured 36 + 4.9 × 16.7 + 2.2 μm (n = 20). Both conidia and symptoms of this powdery mildew are comparable to those previously given for the Erysiphe sp. described in New York (2). Another powdery mildew of tomato, caused by Oidiopsis sicula Scalia, occurs in the western U.S., Mediterranean Basin, Africa, and Asia. However, the conidia of O. sicula are of two types, pyriform and cylindrical, and they are larger than those of an Erysiphe sp. (1). To verify pathogenicity of this Erysiphe sp. to tomatoes, conidia washed from leaves were misted onto uninfected leaves of young tomato plants. After 1 week in a growth chamber (25°C; 80% relative humidity; 12 h of light), typical powdery mildew symptoms were evident on inoculated plants, while unmisted plants remained free of symptoms. Microscopic examination of the fungus on surfaces of leaves confirmed it to be an Erysiphe sp. References: (1) R. N. Campbell and R. W. Scheuerman. Plant Dis. Rep. 63:1087, 1979. (2) D. M. Karasevicz and T. A. Zitter. Plant Dis. 80:709, 1996.
First Report of Stevia as a Host of Sclerotinia sclerotiorum
Authors: Chang K. F. , Howard R. J. , Gaudiel R. G. , Hwang S. F. 
Published: May 2007

Stevia (Stevia rebaudiana Bertoni; Asteraceae), an annual plant originating from Paraguay, contains glucosides of a diterpenoid (2), which is used as a low-caloric sweetener in some South American and southeast Asian countries. The main active ingredient, stevioside, is 100 to 300 times as sweet as sucrose. Stevia has been experimentally grown under field conditions in central and western Canada and has the potential to become a commercially viable alternative crop. In August 1996, a previously undescribed stem rot disease was observed on stevia plants at the Crop Diversification Centre South, Brooks, Alberta. The disease was found in research plots where 4-month-old plants were growing in loam soil. Diseased stems showed dark brown lesions above and at soil level when plant height reached approximately 30 cm. Under dry conditions, mild stem lesions caused plant stunting with lower leaves turning black and curling downward. Wilted leaf symptoms gradually spread upward in affected plants. Partial wilting symptoms appeared when girdling was restricted to branches. The entire plant collapsed when girdling of the crown and roots occurred. Superficial white mycelium developed over the basal part of affected stems under moist conditions, especially after rainy periods. Black, round to oblong sclerotia, 3.5 to 10.1 mm in size, formed externally on the crown areas after plant death. Sclerotinia sclerotiorum (Lib.) de Bary (1) was consistently isolated from the diseased plants. To confirm pathogenicity, 4-week-old stevia seedlings were obtained from shoot cuttings and grown in 12-cm pots of soilless mix. Sclerotia produced on potato dextrose agar were inserted into the mix 0.5 cm deep and 0.5 cm from the stems of test plants. Plants were placed in a growth chamber at 22°C with a 12-h photoperiod and 95% relative humidity. Two weeks after soil infestation, plants wilted and S. sclerotiorum was reisolated from the diseased crown tissues. This is the first report on stevia of sclerotinia stem rot, a disease that could significantly reduce foliar growth and stevioside production in field plantings. References: (1) L. H. Purdy. Phytopathology 69:875, 1979. (2) T. Robinson. 1991. The Organic Constituents of Higher Plants: Their Chemistry and Interrelationships. 6th ed. Cordus Press, North Amherst, MA.
Pathogenicity of Fusarium oxysporum f. sp. phaseoli Isolates from Spain to Phaseolus vulgaris
Authors: Velasquez-Valle R. , Schwartz H. F. , Díaz-Mínguez J. M. 
Published: May 2007

Fusarium oxysporum Schechtend.:Fr. f. sp. phaseoli J. B. Kendrick & W. C. Snyder (FOP) is the causal agent of the common bean (Phaseolus vulgaris L.) disease known as Fusarium wilt or Fusarium yellows. FOP has been reported from the Castilla y Leon region in Spain, where it is a serious problem on most commercial bean cultivars (1). Five FOP isolates from Spain (AB-6, AB-111, AB-112, AS-1, and AS-4) obtained from J. M. Díaz-Mínguez and the isolate FOP-CO1 (ATCC 90245) from Colorado were tested for pathogenicity on two American lines: Pinto U.I. 114, considered as a universal susceptible check, and Flor de Mayo, a Mexican landrace. Seedlings were root-clip inoculated and evaluated according to the CIAT 1 to 9 severity scale, in which 1 to 3 = resistant, 3.1 to 6 = intermediate, and 6.1 to 9 = susceptible. Three inoculum concentrations were tested: 104, 105, and 106 conidia/ml. AS-1 and AS-4 produced resistant reactions in both U.I. 114 (1.5 to 2.1 and 1.2 to 1.5) and Flor de Mayo (1.9 to 2.3 and 1.4), respectively, at all inoculum concentrations. Susceptible reactions to AB-6 (7.3 to 8.9), AB-111 (7.6 to 8.9), AB-112 (7.5 to 7.9), and FOP-CO1 (8.1 to 8.6) were observed in Pinto U.I. 114, regardless of inoculum concentration, although severity ratings increased as the inoculum concentration was increased. Flor de Mayo exhibited a susceptible reaction (6.7 to 7.8) to FOP-CO1 at all inoculum concentrations tested, and intermediate reactions to AB-6 (4.9), AB-111 (5.4), and AB-112 (5.0) at the lowest inoculum concentration. Susceptible reactions (7 to 8.2 for AB-6; 6.8 to 7.0 for AB-111, and 7.3 to 7.7 for AB-112) occurred with higher inoculum concentrations, and severity ratings increased as the inoculum concentration increased. Recently, FOP isolates from Greece and Italy were recognized as each belonging to different pathogenic races (2); consequently, more research on the Spanish isolates (AB-6, AB-111, and AB-112) is needed to determine if they are similar to the races reported from the Mediterranean Basin or should be classified as a new FOP race (s). References: (1) J. M. Díaz-Mínguez et al. Plant Dis. 80:600, 1996. (2) S. L. Woo et al. Phytopathology 86:966, 1996.
First Report of Rhizoctonia solani Causing a Foliar Leaf Spot on Brazilian Pepper-tree (Schinus terebinthifolius) in Florida
Authors: Semer C. R. , Charudattan R. 
Published: May 2007

The Brazilian pepper-tree (Schinus terebinthifolius Raddi) native to Brazil, recently has become an aggressive perennial weed in southern Florida. During a survey in December 1995, a foliar disease was observed on several pepper-tree plants in Palm Beach County. Disease symptoms consisted of dark, reddish-purple necrotic lesions, either with or without dry necrotic centers, that were distributed randomly over the leaf surface. Infected leaf samples from two separate sites were plated on potato dextrose agar (PDA; Difco) and water agar and incubated at 25°C in the dark. A fungus resembling a Rhizoctonia sp. was consistently recovered. To prove Koch's postulates, the fungus was grown on PDA for 10 to 14 days, and the cultures blended in a Waring blender. Metamucil (Procter & Gamble) was added to the mixture at the rate of 0.5% wt/vol, and the suspension was used to spray and inoculate 2- and 3-month-old Brazilian pepper-tree seedlings. Seedlings were sprayed until the inoculum dripped off the foliage and after inoculation were maintained at 100% relative humidity. After 48 h in the dew chamber the inoculated seedlings were moved to a greenhouse bench and examined for infection 5 and 10 days later. Inoculation was completed three times with the leaf lesions occurring 94 to 100%. A Rhizoctonia sp. was recovered from the lesions that appeared on the challenged plants. A determination of the anastomosis group was performed by plating it against the tester isolates of R. solani, AG1-1A, AG2-2IV, AG-3, AG-4, and AG-5. In two separate tests anastomosis (imperfect fusion) (1) was observed between the recovered Rhizoctonia sp. and tester strain AG2-2IV of R. solani. The fungus was identified as R. solani, and this is the first report of R. solani causing a leaf lesion of Brazilian pepper-tree in Florida. The potential of this R. solani as a biological control agent of Brazilian pepper-tree remains to be tested. Reference: (1) B. Sneh et al. Identification of Rhizoctonia Species. American Phytopathological Society, 1991.
First Report of Pythium myriotylum on Lemna gibba in Israel
Authors: Flaishman M. A. , Hadar E. , Hallak-Herr E. 
Published: May 2007

Much interest has focused on duckweed as an alternative food source. Commercial production of Lemna gibba was initiated in Israel in 1991. During the summers of 1994 and 1995, Lemna gibba was grown commercially in covered ponds. In these two seasons, the plants were found to be infected by Pythium myriotylum, which has previously been reported as a pathogen of duckweed (1). In the ponds where the plants were held at high density, small, wilted, white patches of plants were recognized in early June. By the end of the month over 70% of the plants were infected and died. Microscopic examination of infected plants showed the presence of fungal appressoria and mycelial growth. Fungi were isolated from the plants onto potato dextrose agar (PDA). Ten isolates grown on PDA for 7 days were used to inoculate healthy plants. After 12 days, symptoms developed on plants at 28 or 32°C. Symptoms were similar to those observed on pond-grown plants. Plants maintained at 17 or 22°C did not become infected. The results from the pond and laboratory work showed that high plant density and temperature above 24°C were necessary for infection, and infection takes place by hyphal elements that spread in the water. This is the first report of Pythium myriotylum on Lemna gibba in Israel. Reference: (1) E. Rejmankova et al. Veröff. Geobot. Inst. Eidg. Tech. Hochsch. Stift. Rübel, Zür. 87:178, 1986.
First Report of Lettuce Chlorosis Virus Naturally Infecting Sugar Beets in California
Authors: Wisler G. C. , Duffus J. E. , Gerik J. S. 
Published: May 2007

Sugar beet (Beta vulgaris) plants showing interveinal yellowing and thickened leaves were collected from two fields in Imperial County, CA, for disease assessment in January 1996. Yellowing symptoms were widespread in these fields during the winter of 1995 to 1996. Initial enzyme-linked immunosorbent assays (ELISA) with polyclonal antiserum (ATCC) for beet western yellows virus were consistently negative. Inoculations with Bemisia tabaci “B” biotype (B. argentifolii) whiteflies onto the indicator plants Chenopodium capitatum, C. murale, lettuce (Lactuca sativa), and sugar beet resulted in interveinal yellowing, reddening, and thickened leaves characteristic of whitefly-transmitted closteroviruses (1). Western blot (immunoblot) analyses were performed with antisera to the purified virions of lettuce chlorosis virus (LCV) and lettuce infectious yellows virus (LIYV). Tissue extracts from original beet plants representing two fields and from all subsequent whitefly-inoculated indicator plants consistently showed a single band at ca. 32 kDa, reported to be the molecular mass for LCV capsid protein. Corresponding Western blot analyses for LIYV with the same tissue extracts were negative. No reactions were observed in Western blot assays with tissue extracts from healthy plants. Although sugar beet is a host for LCV as shown by laboratory experiments (1), this is the first report of a natural infection of LCV in sugar beet. Reference: (1) J. E. Duffus et al. Eur. J. Plant Pathol. 102:591, 1996.
First Report of Phomopsis longicolla Infection of Cowpea Pods and Seeds in Mississippi
Authors: Roy K. W. , Ratnayake S. 
Published: May 2007

Mature cowpea (Vigna unguiculata (L.) Walp.) pods with scattered, irregular black spots, similar in appearance to those found on mature soybean (Glycine max (L.) Merr.) pods infected with Phomopsis longicolla T. W. Hobbs, were observed in three fields in Oktibbeha County, MS, in September 1994. In a delayed harvest sample of pods and seeds from one field, a fungus identified as P. longicolla (1) was isolated from more than 60% of surface-disinfested, excised pod disks and from 42% of surface-disinfested seeds. Average frequencies of isolation from seeds harvested at the normal time from the other two fields were 27 and 9%. When surface-disinfested soybean seeds (cv. Avery) were placed along the margins of P. longicolla colonies on potato dextrose agar, the radicals from most germinating seeds became necrotic and many seeds did not germinate. Koch's postulates were completed by reisolating the fungus from diseased tissue. Reference: (1) T. W. Hobbs et al. Mycologia 77:535, 1985.
Occurrence of Vine Decline Diseases of Muskmelon in Guatemala
Authors: Bruton B. D. , Miller M. E. 
Published: May 2007

Central American countries have become major production areas of melons (Cucumis melo L.) destined for export to Europe and the United States during the winter months. Double cropping in the same fields year after year has created serious vine decline diseases in melons grown in the Capco area of Guatemala. Vines typically appear healthy until the fruit are approaching maturity, when the crown leaves begin to turn yellow and collapse and the decline gradually radiates outward. There was evidence of slightly water-soaked lesions in the crown of some plants; however, the symptoms were not similar to charcoal rot or gummy stem blight. The roots exhibited some decay, lesions, and discoloration, but were not macerated and rotten. A minimum of 10 affected plants were collected from each of nine fields in the Capco area of Guatemala. Isolations were made from the crown area, primary root, and secondary roots of selected plants by excising 3- to 5-mm pieces and surface sterilizing them for 30 to 60 s with 0.5% sodium hypochlorite. The isolations were made on 2% water agar plus 0.1 g of streptomycin sulfate per liter. Plates were examined for fungal growth daily for 5 days with hyphal tips from all colonies transferred to potato dextrose agar and Synthetischer nährstoffärmer agar (2) and allowed to sporulate. Isolations revealed the presence of several fungi capable of causing vine decline or suspected of being involved in the vine decline complex. Rhizoctonia solani Kühn and Fusarium semitectum Berk. & Ravenel were isolated from more than 50% of plants in some fields. F. semitectum, R. solani, and a Stagonospora-like fungus were isolated from 38, 18, and 17% of the total plants, respectively. R. solani was isolated from the crown more often than from the roots, but its role is not understood. With one exception, F. semitectum was always isolated from the crown area, which may suggest a more significant role in the vine decline complex than suspected previously. The Stagonospora-like fungus, isolated from 30% of the plants from one field, has been reported as a pathogen of cantaloupe that may contribute to the vine decline complex (1). Monosporascus cannonballus Pollack & Uecker and Fusarium oxysporum Schlechtend.:Fr. emend. W. C. Snyder & H. N. Hans. were isolated from 60% of the plants from one field. It was the only field in which M. cannonballus was isolated. Plectosporium tabacinum (van Beyma) M. E. Palm, W. Gams et Nirenberg, a cucurbit pathogen, was isolated infrequently. This is the first report of M. cannonballus, P. tabacinum, and the Stagonospora-like fungus in Guatemala. References: (1) M. E. Miller et al. Phytopathology 86:S3, 1996. (2) H. I. Nirenberg. Mitt. Biol. Bundesanst. Land Forstwirtsch. Berlin-Dahlem. 169:1, 1976.
First Report of Colletotrichum gloeosporioides f. sp. manihotis, Cause of Cassava Anthracnose Disease, Being Seed-borne and Seed-Transmitted in Cassava
Authors: Fokunang C. N. , Ikotun T. , Dixon A. G. O. , Akem C. N. 
Published: May 2007

Cassava anthracnose disease is a major economic disease of cassava in the tropics (2). Infection can lead to a significant loss in planting materials and total field crop failure. The disease has been reported to be transmitted mainly by a bug (Pseudotheraptus devastans Dist) (1). Open pollinated seeds from 13 cassava (Manihot esculenta Crantz) genotypes, stored for 10 months after harvest in 1994, were used to investigate the presence of the cassava anthracnose disease fungus. Seeds, 200 from each genotype, were surface sterilized, cultured on potato dextrose agar (PDA), and incubated for 8 days, at 25 ± 2°C. Microscopic examination indicated that Colletotrichum gloeosporioides was one of the seed-borne fungi, with up to 40% incidence recorded in some genotypes. Seeds from five susceptible genotypes selected for seed transmission studies were planted in fine, steam-sterilized soils in jiffy pots and watered daily for seedling emergence. At a height of 10 to 15 cm, the seedlings were transferred to plastic pots (10.5 cm in diameter) filled with sterilized mixture of soil and sand (2:2, vol/vol). Pots were placed close to each other to obtain a thick plant canopy. Temperature of 25 to 32°C and humidity of 80 to 98% were maintained. After 45 days, some plants had cassava anthracnose symptoms, including defoliation, wilt, and necrotic lesions. Stems, leaves, and roots of infected plants were washed, surface sterilized, and plated on PDA for 5 to 7 days. Microscopic observation of the fungus showed conidia of C. gloeosporioides. The rest of the plants were monitored for 3 months under vector-free conditions for typical anthracnose symptoms. Mean maximum wilt and defoliation of 35 to 38% was recorded in some genotypes. Conidial suspensions of C. gloeosporioides were used in stem-puncture inoculations of young, healthy cassava plants. The typical anthracnose symptoms of stem necrosis were observed 2 weeks after inoculation, confirming isolates as C. gloeosporioides f. sp. manihotis. This is the first report of C. gloeosporioides f. sp. manihotis being seed-borne and seed-transmitted in cassava. References: (1) B. Boher et al. Agronomie 3:989, 1983. (2) J. C. Lozano. PANS 20:30, 1974.
Occurrence of Squash Mosaic Comovirus Infecting Summer Squash (Cucurbita pepo) in South Dakota and Transmission by Diabroticabarberi
Authors: Langham M. A. C. , Gallenberg D. J. , Gergerich R. C. 
Published: May 2007

Summer squash (Cucurbita pepo L.) exhibiting strong mosaic symptoms and leaf deformations were found in Brookings County during the summers of 1994 and 1995. Four isolates were mechanically transmitted to C. pepo cv. Early Prolific Straightneck. Ouchterlony double diffusion tests (conducted both in Arkansas and South Dakota) and protein-A enzyme-linked immunosorbent assays (ELISAs) with squash mosaic virus (SqMV) antisera provided by R. C. Gergerich were positive for SqMV. Pumpkin mosaic virus, a strain of SqMV, was previously reported infecting pumpkin in South Dakota (1). The pumpkin strain was differentiated from other strains of SqMV by its ability to infect lentil (Lens esculenta Moench), garden pea (Pisum sativum L.), and fenugreek (Trigonella foenum-graecum L.). The South Dakota isolates in this study did not infect these hosts, although the Arkansas isolate was found to infect Pisum sativum cvs. Little Marvel and Dwarf Gray Sugar Pod when tested serologically. The presence of adult Diabrotica undecimpunctata howardii Barber and D. barberi (Smith and Lawrence) was noted on infected plants in the area. Transmission tests were conducted with D. barberi provided by the USDA-ARS Northern Grain Insect Research Laboratory, Brookings, SD. The beetles had been previously reared on artificial diet media and germinated corn seed. Individual beetles were given a 48-h acquisition access period on infected or healthy detached squash leaves in petri dishes followed by a 48-h inoculation access period on Early Prolific Straightneck squash plants (1 beetle per plant). Beetles were removed at the end of this period, and the plants were grown under greenhouse conditions for 3 weeks. Plants were assayed for SqMV by protein-A ELISA. Transmission percentages of SqMV were as follows: SqMV (Arkansas isolate), 16.7%; and four South Dakota isolates, 12.5, 11.4, 14.6, and 5.1%. Beetles fed on healthy plants did not transmit virus. The rate of transmission found in this study indicates that D. barbari serves as an efficient vector for the transmission of SqMV in field plantings. Reference: (1) W. N. Stoner. Proc. S. D. Acad. Sci. 56:178, 1977.
First Report of Grapevine Virus A in Spain
Authors: Zabalgogeazcoa I. , de Blas C. , Cabaleiro C. , Segura A. , Ponz F. 
Published: May 2007

Grapevine trichovirus A (GVA), a flexuous, filamentous, phloem-limited virus with an approximately 7.3-kbp RNA genome, is widespread in grapevines showing symptoms of leafroll and/or rugose wood. The virus can be mechanically inoculated to Nicotiana benthamiana and N. clevelandii. A field survey of diseased Vitis vinifera white and red cultivars was carried out in Pontevedra (northwest Spain) during the autumn of 1993. We detected the presence of GVA in vines showing leafroll symptoms by an immunocapture-reverse transcription-polymerase chain reaction (PCR) method (2) with GVA-specific primers (1). Bands of the expected size of 430 bp were obtained with extracts from petioles and stem bark as reaction substrates. To verify these results, Northern (RNA) blots with double-stranded (ds) RNAs isolated from grapevines were prepared. Hybridization was positive in two out of 10 samples analyzed. The probe was a 32P-labeled 430-bp PCR product amplified from extracts of N. benthamiana plants infected with GVA strain Is151 (gift of A. Mina-fra). The specificity of this probe was confirmed in dot blot hybridization, as a positive signal was obtained with extracts from GVA-inoculated N. benthamiana, but not with extracts of phosphate buffer-inoculated N. benthamiana, turnip mosaic potyvirus-inoculated Arabidopsis thaliana, or potato potyvirus Y-inoculated N. xanthi plants. The probe did not hybridize to dsRNAs extracted from enzyme-linked immunosorbent assay-positive GLRaV-III-infected grapevines. GVA has been identified in other Mediterranean countries, but to our knowledge this is the first report of the detection of GVA in Spain. References: (1) A. Minafra and A. Hadidi. J. Virol. Methods 47:175, 1994. (2) G. Nolasco et al. J. Virol. Methods 45:201, 1993.