scholarly journals Occurrences of Diplodia Leaf Streak Caused by Stenocarpella macrospora on Corn (Zea mays) in Illinois

Plant Disease ◽  
2010 ◽  
Vol 94 (10) ◽  
pp. 1262-1262 ◽  
Author(s):  
C. A. Bradley ◽  
D. K. Pedersen ◽  
G. R. Zhang ◽  
N. R. Pataky
Keyword(s):  
United States ◽  
Zea Mays ◽  
Morphological Characteristics ◽  
The United States ◽  
Small Subunit ◽  
Minor Importance ◽  
United States Department ◽  
Conidial Suspension ◽  
Small Subunit Rdna ◽  
Corn Fields

In August 2008, long and narrow lesions were observed on leaves of corn (Zea mays L.) growing in a field in Pope County, Illinois. Lesions were 10 to 35 × 50 to 250 mm and were cream to tan. Dark pycnidia inside the lesions were immersed and approximately 350 μm in diameter. Affected leaves were collected and placed into a moist chamber to encourage the development of conidia. Conidia developed in cirri and were dark, one septate, and 7 to 11 × 59 to 87 μm. Cirri were streaked onto potato dextrose agar (PDA; Becton, Dickinson, and Company, Franklin Lakes, NJ) and cultures arising from single conidia were transferred and maintained. On the basis of the corn leaf symptoms and the morphological characteristics of the pycnidia and conidia, the fungus was tentatively identified as Stenocarpella macrospora (Earle) Sutton (1). To complete Koch's postulates, ‘Garst 84H80-3000GT’ corn was inoculated in the greenhouse. Conidia were produced by placing a S. macrospora isolate from Pope County, IL onto water agar containing autoclaved corn leaves and incubating at room temperature until pycnidia and conidia were produced (approximately 3 weeks). A conidial suspension was used to inoculate the leaf whorls of corn plants (approximately at the V4 growth stage). Control plants were mock inoculated with sterile water. The experiment was repeated once over time. Twenty days after inoculation, all plants inoculated with S. macrospora conidia developed lesions similar to those observed in the field, and mock-inoculated plants remained symptomless. The fungus was reisolated on PDA from the symptomatic leaves. In August 2009, symptomatic leaves similar to those observed in Pope County, IL in 2008 were observed and collected from corn fields in Gallatin and Vermillion counties. Pycnidia and conidia from these lesions were similar to those described above, and isolates from single conidia were obtained from these samples. To confirm the identity of all isolates collected, PCR amplification of the small subunit rDNA and internal transcribed spacer (ITS) region with primers EF3RCNL and ITS4 was conducted (3). The PCR product was sequenced with these primers at the Keck Biotechnology Center at the University of Illinois, Urbana. The resulting nucleotide sequence was compared with small subunit rDNA and ITS sequences deposited in the GenBank nucleotide database, which revealed 99% homology to sequences of S. macrospora. In total, six of our S. macrospora isolates from Gallatin, Pope, and Vermillion counties were submitted to the United States Department of Agriculture–Agriculture Research Service Culture Collection in Peoria, IL, where they have received NRRL Accession Nos. 54190–54195. To our knowledge, this is the first report of S. macrospora affecting corn in Illinois. Although not observed in the Illinois corn fields described above, S. macrospora has been reported to infect stalks and ears (2). Because of the large leaf lesions caused by S. macrospora and its reported aggressiveness in causing disease on leaves, ears, and stalks, this pathogen has the potential to cause severe yield and quality losses to corn in the United States (2). References: (1) M. L. Carson. Diseases of minor importance or limited occurrence. Page 23 in: Compendium of Corn Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 1999. (2) F. M. Latterell and A. E. Rossi. Plant Dis. 67:725, 1983. (3) N. S. Lord et al. FEMS Microbiol. Ecol. 42:327, 2002.

scholarly journals First Report of Leaf Spot of Smooth Bromegrass Caused by Pithomyces chartarum in Nebraska

Plant Disease ◽  
2006 ◽  
Vol 90 (1) ◽  
pp. 108-108 ◽  
Author(s):  
C. Eken ◽  
C. C. Jochum ◽  
G. Y. Yuen
Keyword(s):  
United States ◽  
Relative Humidity ◽  
Morphological Characteristics ◽  
The United States ◽  
Grass Species ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Smooth Bromegrass ◽  
Decay Fungi ◽  
Wide Range

Smooth bromegrass (Bromus inermis Leyss.) is the most common perennial grass species cultivated for forage in North America. During late fall of 2004, smooth bromegrass plants in Lincoln, NE were observed to have brown lesions on leaf midveins that were several centimeters long. Symptomatic leaves were surface disinfested for 1 min in 2% NaOCl and incubated at 25°C on potato dextrose agar (PDA) and water agar. The fungus, Pithomyces chartarum (Berk. & Curt) Ellis, was isolated consistently and identified on the basis of morphological characteristics (1). Colonies were effused and black on PDA. Conidiophores measured 3.5 to 8 × 1.9 to 3.9 μm and were smooth and single. Conidia (7 to 25 × 9.5 to 14 μm) were broadly ellipsoidal, pale brown to dark brown, verrucose with mainly three transverse septa and one to two longitudinal septa. Pathogenicity tests were conducted on 50-day-old plants by spraying with a conidial suspension (2.5 × 105 spores per ml). Control plants were sprayed with sterile water. All plants were kept in a moist chamber (100% relative humidity) for 3 days and then transferred to a greenhouse (25°C, >70% relative humidity, and a 12-h photoperiod). One week after spraying, elongated lesions developed on leaf midveins of inoculated plants from which P. chartarum was consistently reisolated. No symptoms were observed on control plants. While P. chartarum has been described as a saprotroph or a parasite on a wide range of plants primarily in the tropics and subtropics, including the southern United States (2), it was reported previously on B. inermis only in Canada (3). This report expands the distribution and host range of P. chartarum as a pathogen in the United States. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) D. F. Farr et al. Fungal Databases, Systematic Botany and Mycology Laboratory, On-line publication. ARS, USDA, 2005. (3) J. H. Ginns. Compendium of Plant Disease and Decay Fungi in Canada 1960-1980. Res. Br. Can. Agric. Publ. 1813, 1986.

scholarly journals First Report of Verticillium Wilt Caused by Verticillium dahliae on Rudbeckia fulgida (Orange Coneflower) in Italy

Plant Disease ◽  
2008 ◽  
Vol 92 (9) ◽  
pp. 1367-1367 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Vascular Tissue ◽  
Morphological Characteristics ◽  
Its Region ◽  
The United States ◽  
Conidial Suspension ◽  
First Report ◽  
Initial Symptoms

Rudbeckia fulgida (common name orange coneflower) is an herbaceous perennial (Asteraceae) grown in full sun in perennial borders in gardens. At the end of the summer of 2007, in a public garden located in Turin (northern Italy), symptoms of vascular wilt and stunting were observed on approximately 80% of the plants grown in a mixed border. Initial symptoms were yellowing of external leaves and brown or black streaks in the vascular tissue of roots, crown, and leaves. A fungus was consistently and readily isolated on potato dextrose agar from symptomatic vascular tissue previously disinfested in 1% sodium hypochloride. Ovoid, dark microsclerotia, 41 to 108 μm, developed in hyaline hyphae after 10 days of growth at 23°C (12 h of light and 12 h of dark). Hyaline, elliptical, single-celled conidia, 3.2 to 7.3 × 2.1 to 3.7 (average 4.7 × 2.8) μm, developed on verticillate conidiophores. On the basis of these morphological characteristics, the fungus was identified as Verticillium dahliae (4). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 530 bp showed a 100% homology with the sequence of V. dahliae. The nucleotide sequence has been assigned GenBank Accession No. EU 627007. Healthy, 30-day-old R. fulgida plants were grown in a steam-disinfested mix of sphagnum peat:pomix:pine bark:clay (50:20:20:10) infested with a conidial suspension (1.5 × 106/ml) of three isolates of V. dahliae isolated from infected plants. Noninoculated plants served as controls. Plants (16 per treatment) were grown in pots (3 liter vol) and maintained in a glasshouse at temperatures between 22 and 25°C and relative humidity between 50 and 70%. First wilt symptoms and vascular discoloration in the roots, crown, and veins developed 17 days after inoculation. Noninoculated plants remained healthy. The pathogenicity tests were carried out twice. To our knowledge, this is the first report in Italy of Verticillium wilt on R. fulgida. Wilts caused by V. dahliae on R. laciniata in Poland (3) and V. albo-atrum on R. hirta in the United States (2) were previously reported. The importance and economic impact of this disease is currently limited but may increase because of the popularity of Rudbeckia spp. in private and public parks. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) D. F. Farr et al. Fungi on Plants and Their Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (3) B. Leski. Rocz. Nauk Roln. 253, 1974. (4) G. F. Pegg and B. L. Brady. Verticillium Wilts. CABI Publishing, Wallingford, UK, 2002.

Photovoltaics in the United States Department of Defense

1996 ◽  
Author(s):  
J. F. Hoelscher ◽  
R. Ducey ◽  
G. D. Smith ◽  
L. W. Strother ◽  
C. Combs
Keyword(s):  
United States ◽  
Department Of Defense ◽  
The United States ◽  
United States Department ◽  
States Department

scholarly journals Corn (Zea mays L.) Genetics in the United States

Nature ◽  
1948 ◽  
Vol 161 (4080) ◽  
pp. 42-44
Author(s):  
GORDON HASKELL
Keyword(s):  
United States ◽  
Zea Mays ◽  
Zea Mays L ◽  
The United States

scholarly journals Exotic Haemaphysalis longicornis (Acari: Ixodidae) in the United States: Biology, Ecology, and Strategies for Management

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Brittany L Schappach ◽  
Rayda K Krell ◽  
Victoria L Hornbostel ◽  
Neeta P Connally
Keyword(s):  
United States ◽  
Vector Competence ◽  
The United States ◽  
United States Department ◽  
Haemaphysalis Longicornis ◽  
Life Stages ◽  
Department Of Agriculture ◽  
Management Options ◽  
Significant Public Health ◽  
Multiple Pathogens

Abstract The Asian longhorned tick (ALT), Haemaphysalis longicornis Neumann (Acari: Ixodidae), is a three-host tick that was first detected outside of United States Department of Agriculture (USDA) quarantine in Hunterdon County, New Jersey, in 2017 and subsequently found in another 14 states. In its native Asia, and where it has become established in Australia and New Zealand, ALTs feed on a variety of hosts and are economically important livestock pests and competent vectors of multiple pathogens to humans and other animals. The degree to which ALT will become a persistent livestock pest or competent vector for introduced or existing pathogens in the United States is yet unclear. Because of its vast host availability, ability to reproduce asexually, known vector competence, and the presence of multiple life stages on hosts, the expansion of ALT establishment in the United States is expected, and is a significant public health and veterinary concern. In this paper, we discuss the biology, geographical distribution, life cycle and seasonal activity, reproduction, identification, medical and veterinary implications, management options, and future concerns in the United States.

Sign in / Sign up

Export Citation Format

Share Document