bluuebunny/crossref_metadata_2025 huggingface dataset:
Management of Early Leaf Spot of Peanut with Pyraclostrobin as Affected by Rate and Spray Interval
Authors: Culbreath A. K. , Brenneman T. B. , Kemerait R. C.
Published: May 2008

Field tests were conducted in Tifton, Georgia, in 1998 to 2000 and in Plains, Georgia, in 1999 and 2000 to determine the efficacy of pyraclostrobin on early leaf spot (Cercospora arachidicola) of peanut (Arachis hypogaea). Application regimes included three rates (112, 168, and 224 g a.i./ha) of pyraclostrobin applied on 14-, 21-, and 28-day schedules. These were compared to currently-used fungicides chlorothalonil, tebuconazole, and azoxystrobin. In all tests, application of pyraclostrobin at rates of 168 g/ha or higher gave better leaf spot control than chlorothalonil applied at 1.26 kg/ha or tebuconazole applied at 227 g/ha on the same schedule. At both Plains and Tifton, plots treated four times with pyraclostrobin at 168 or 224 g/ha on a 28-day schedule had final leaf spot intensity ratings that were similar to those of standard rates of chlorothalonil or tebuconazole applied seven times on a 14-day schedule. At Tifton, all three rates of pyraclostrobin applied five times on a 21-day schedule had final leaf spot ratings lower than those of plots treated with seven applications of chlorothalonil or tebuconazole on a 14-day schedule. There was little improvement in leaf spot control with rates of pyraclostrobin higher than 168 g/ha in any test or application schedule. Fungicide effects on yield were not consistent, but in all tests, yields from plots treated with any of the three rates of pyraclostrobin were similar to or higher than yields from plots treated with 227 g/ha of tebuconazole on the same schedule. The ability to use pyraclostrobin at 21-day intervals and maintain control of early leaf spot similar to that of application of currently available fungicides at 14-day intervals represents potential savings in time, fuel, labor, and equipment costs.

Accepted for publication 14 October 2002. Published 18 October 2002.
Confirmation of Shattercane (Sorghum bicolor) Resistance to ALS-Inhibiting Herbicides in Ohio
Authors: Brenly-Bultemeier Traci L. , Stachler Jeff , Harrison S. Kent
Published: May 2008

A population of shattercane (Sorghum bicolor (L.) Moench) located in Fairfield County, Ohio, was investigated for herbicide resistance after it persisted in a field that had been treated repeatedly with herbicides that inhibit acetolactate synthase (ALS). Herbicide bioassays confirmed cross-resistance of the suspected resistant (R) population to the ALS inhibitors nicosulfuron, primisulfuron, and imazethapyr. Herbicide doses required to reduce R shattercane shoot dry weight 50% (i.e., the GR50 values) were > 35,000, > 40,000, and 34,215 g ai/ha for nicosulfuron, primisulfuron, and imazethapyr, respectively. In contrast, GR50 values for the same herbicides applied to a susceptible (S) shattercane population from an adjacent county were 0.185, 0.025, and 0.038 g/ha, respectively. The high levels of resistance exhibited by the R population suggest that the resistance mechanism is due to one or more alterations in ALS, the herbicide target site. Effective management of ALS herbicide-resistant shattercane will require an integrated strategy designed to isolate the R population and deplete its soil seed bank while minimizing herbicide selection pressure.

Accepted for publication 14 October 2002. Published 21 October 2002.
Detecting Single Seeds of Small Broomrape (Orobanche minor) with a Polymerase Chain Reaction
Authors: Osterbauer Nancy K. , Rehms Lisa
Published: May 2008

The seeds of the federally-listed noxious weed and parasitic plant small broomrape (Orobanche minor Smith) are extremely small, averaging 200 to 300 μm in size. Because of its miniscule seed size, contamination of fields and seed lots by small broomrape seeds is difficult to detect and confirm via conventional methods. Complementary polymerase chain reaction (PCR) primers based upon unique sequences in the internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA (nrDNA) of small broomrape were developed. The PCR amplified small broomrape DNA and did not amplify DNA from other Orobanche species with similar host ranges found in Oregon. The primers also did not amplify the DNA of red and white clover (Trifolium pratense L. and T. repens L., respectively), two agricultural hosts for this parasite. The PCR-based assay was sensitive enough to detect a single small broomrape seed.

Accepted for publication 14 October 2002. Published 18 October 2002.
Recent Trends in Microbiological Safety of Fruits and Vegetables
Authors: Buck J. W. , Walcott R. R. , Beuchat L. R.
Published: May 2008

No single strategy will be successful in eliminating contamination of fresh produce and seed by human pathogenic bacteria, but a multi-pronged approach may reduce the risks of outbreaks. An integrated pest management model is likely to work for minimizing the risk of human pathogenic bacteria on seed and fresh produce.

Accepted for publication 20 December 2002. Published 21 January 2003.
Particle Film, Surround WP, Effects on Glassy-winged Sharpshooter Behavior and Its Utility as a Barrier to Sharpshooter Infestations in Grape
Authors: Puterka Gary J. , Reinke Mike , Luvisi Donald , Ciomperik Matthew A. , Bartels David , Glenn D. Michael
Published: May 2008

Glassy-winged sharpshooter (GWSS) was recently introduced into California and poses a serious threat to the grape industry because it is a very effective vector of the bacterium that causes Pierce's disease. We studied how GWSS was affected by a new technology called particle film, Surround™ WP, that protects plants from insect feeding, oviposition, and infestation by coating the plant surfaces with a protective mineral barrier. In caged field studies, we found that GWSS nymphs and adults were highly repelled by lemon trees treated with Surround WP. Applications of Surround WP turn foliage white; thus, we compared the attractiveness of white and other colors with yellow, which is extremely attractive to GWSS. This study showed that yellow was the most attractive color, followed by orange, and that white was among the least attractive colors, suggesting that Surround WP applications may make plants unrecognizable as hosts. In a field study that compared three biweekly Surround WP treatments to six weekly contact insecticide treatments, Surround WP performed as well as insecticides in reducing GWSS adult numbers and oviposition.

Accepted for publication 25 February 2003. Published 21 March 2003.
First Report of Powdery Mildew of Kalanchoe blossfeldiana caused by Sphaerotheca fuliginea (Podosphaera fuliginea) in the Pacific Northwest
Authors: Glawe Dean A. , Hummel Rita , Jack Grace
Published: May 2008

Kalanchoe blossfeldiana Poelln. is a common ornamental houseplant. Although powdery mildew is a major disease of this species, there are no published reports of it in the Pacific Northwest. In August, 2002, powdery mildew was observed on six indoor K. blossfeldiana plants in an office and adjacent laboratory at the Puyallup Research and Extension Center.

Accepted for publication 25 March 2003. Published 17 April 2003.
First Report of Powdery Mildew of Magnolia Caused by Microsphaera magnifica (Erysiphe magnifica) in the Pacific Northwest
Authors: Glawe Dean A.
Published: May 2008

Magnolia liliiflora Desrousseaux in Lamarck (orthographic variant: M. liliiflora), a species thought to have originated in China (3), is used as a landscape plant in North America. In August 2002, Microsphaera magnifica U. Braun was collected from three plants of M. liliiflora in the Magnolia collection at the Washington Park Arboretum, University of Washington, Seattle. This report documents for the first time a powdery mildew disease of a Magnolia species in the Pacific Northwest, and the first finding of M. magnifica in the western United States.

Accepted for publication 14 April 2003. Published 12 May 2003.
Diagnosis of Peltamigratus christiei, a Plant-Parasitic Nematode Associated with Warm-Season Turgrasses in the Southern United States
Authors: Crow W. T. , Walker N. R.
Published: May 2008

Various turfgrass species are used as ground cover for residential, commercial, right-of-way, and recreational purposes in the southern United States. Plant-parasitic nematodes are common and destructive pests of both warm- and cool-season turfgrasses. The population diversity and distribution of plant-parasitic nematodes in numerous turfgrass ecosystems have been characterized in this study.

Accepted for publication 4 April 2003. Published 13 May 2003.
Dollar Spot in Four Bentgrass Cultivars as Affected by Acibenzolar-S-Methyl and Organic Fertilizers
Authors: Lee Joon , Fry Jack , Tisserat Ned
Published: May 2008

Golf course superintendents are interested in identifying ways to reduce fungicide inputs on creeping bentgrass (Agrostis palustris Huds.) putting greens. Our objectives were to evaluate the influence of the plant defense activator acibenzolar-S-methyl (ASM, Actigard, Syngenta Corp., Basel, Switzerland) and organic fertilizers on dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn) in four bentgrass cultivars. Crenshaw had over 10 times the area under the disease progress curve (AUDPC) value for dollar spot compared to the cultivar L-93 in 2000. Acibenzolar-S-methyl applied at 35 g a.i. per ha every 14 days between mid-May and mid-September for two consecutive growing seasons reduced the number of S. homoeocarpa infection centers by 15% in Crenshaw, 24% in Penncross, and 29% in Providence, but had no effect on the number of infection centers in L-93. Only Sustane (Crenshaw in 2000) and Milorganite (Crenshaw and Providence in 2001) suppressed dollar spot compared to urea. The following fertilizers resulted in an increase in S. homoeocarpa infection centers: Nature Safe 8-1.3-4.2 in Crenshaw in both years, and in Providence in 2000; Nature Safe 10-0.9-6.6 in Crenshaw in both years; and Sustane with Iron in Crenshaw in 2001. All other organic fertilizer × cultivar combinations resulted in dollar spot levels equivalent to those observed in ureatreated turf. Brown patch levels were not affected by cultivar, ASM, or organic fertilizers. The defense activator ASM deserves further evaluation as a tool to reduce dollar spot-targeted fungicide inputs in creeping bentgrass.

Accepted for publication 5 June 2003. Published 26 June 2003.
Peduncle Rot of Dwarf Wheat caused by Rhizoctonia cerealis
Authors: Lovell D. J. , Parker S. R. , Baldwin S. , Fraaije B. A.
Published: May 2008

Sharp eyespot, caused by the soil-borne fungus Rhizoctonia cerealis Van der Hoeven (teleomorph: Ceratobasidium cereale D. Murray & L.L. Burpee), is a common disease of Graminaceae plants including wheat, barley, oats, and rye. The fungus is prevalent throughout the major wheat growing regions of the world and is sometimes associated with pre- and post-emergence damping off and shoot death of seedlings.

Accepted for publication 16 June 2003. Published 17 July 2003.
Diagnosis of Common Root Rot of Wheat and Barley
Authors: Mathre D. E. , Johnston R. H. , Grey W. E.
Published: May 2008

Diagnosis of common root rot of wheat and barley is discussed in detail, including its symptoms and signs, host range, taxonomy, and geographic distribution, as well as methods of isolation, identification, and storage of the common root rot pathogen.

Accepted for publication 17 July 2003. Published 19 August 2003.
Factors Limiting IPM-Compatibility of New Disease Control Tactics for Apples in Eastern United States
Authors: Rosenberger David A.
Published: May 2008

Economic constraints in the production of apples and perhaps other horticultural crops limit the adoption of many new IPM-friendly technologies. Because of the diminishing profit margins and the complexities involved in evaluating new technologies, farmers will increasingly turn to crop consultants for advice on when and how to integrate new disease-control technologies into their production systems.

Accepted for publication 26 June 2003. Published 26 August 2003.
Responding to an Introduced Pathogen: Podosphaera macularis (Hop Powdery Mildew) in the Pacific Northwest
Authors: Mahaffee Walter F. , Thomas Carla S. , Turechek William W. , Ocamb Cynthia M. , Nelson Mark E. , Fox Alan , Gubler Walter D.
Published: May 2008

Powdery mildew of hop (Humulus lupus L.), which is caused by Podosphaera macularis (formerly Sphaerotheca macularis) was found in the Yakima Valley, WA in 1996 and subsequently spread to the growing regions in Oregon and northern and southern Idaho. To rapidly assist growers in reducing the cost associated with the preventive fungicide program, the Gubler/Thomas grape powdery mildew risk infection model was adapted for hops. In addition, field surveys were utilized to identify other management practices that impacted disease development. Weather networks were established and utilized to deliver daily regional maps indicating the risk index. These maps were posted to the web for daily access. Lessons learned from this experience will be useful in addressing future pathogen introductions.

Accepted for publication 28 March 2003. Published 13 November 2003.
Field Application of Brassicaceous Amendments for Control of Soilborne Pests and Pathogens
Authors: Zasada I. A. , Ferris H. , Elmore C. L. , Roncoroni J. A. , MacDonald J. D. , Bolkan L. R. , Yakabe L. E.
Published: May 2008

Field studies were conducted to evaluate brassicaceous amendments in combination with solarization against diverse soilborne organisms in cut-flower production systems. Across a diversity of California climates, the application of broccoli (Brassica oleracea var. botrytis) did not consistently reduce populations of Fusarium spp., citrus nematode (Tylenchulus semipenetrans), or weeds. Solarization in combination with broccoli amendments did not consistently improve pest suppression in cool coastal regions, whereas solarization was an important component of suppression in the hot central valley. When the biomass of broccoli was increased from 4 to 8.4 dry tons/ha, there was a decrease in survival of weeds and citrus nematode but the effect on Fusarium spp. survival was not consistent. A horseradish (Armoracia lapathifolia) amendment reduced nematode populations compared to broccoli, but increased field bindweed (Convolvulus arvensis L.). Our research demonstrates that soilborne organisms vary greatly in their susceptibility to brassicaceous amendments. The citrus nematode was consistently suppressed by brassicaceous amendments, while the effect on Fusarium spp. and weeds was variable. To achieve consistent and reliable pest suppression in amendment-based management systems, it is essential to determine and understand the component mechanisms active against specific soilborne organisms.

Accepted for publication 10 October 2003. Published 20 November 2003.
Resistance to Take-all is Not Expressed in Wheat-Alien Chromosome Addition and Substitution Lines
Authors: Edmunds Brooke A. , Gleason Mark L.
Published: May 2008

Stalk and petiole rot of herbaceous ornamental perennials, caused by S. rolfsii var. delphinii, is a widespread disease in landscape plantings and nursery production fields in the Midwest United States. A better understanding of perennation of the pathogen could aid in development of more effective management recommendations. Sclerotia of S. rolfsii var. delphinii were produced on strips of inoculated cotton batting placed on moistened sand in a plastic crisper. After one week at 27°C, sclerotia were removed, sealed in nylon mesh bags, and the bags were buried immediately below the soil surface and at 15-cm and 30-cm depths at two locations in Iowa in September 2001. Germination of sclerotia was quantified in October and November 2001 and in April, May, June, and July 2002 by plating recovered, surface-sterilized sclerotia on carrot agar amended with antibiotics. Survival was highly variable but in June and July was greatest at the soil surface (~50%). This is the first documented evidence that S. rolfsii var. delphinii will overwinter in the Midwest and survive a sufficient length of time to cause disease in the next growing season.

Accepted for publication 6 October 2003. Published 24 November 2003.
Gray Leaf Spot of Perennial Ryegrass
Authors: Harmon Philip F. , Latin Richard
Published: May 2008

Diagnosis of gray leaf spot (caused by Magnaporthe oryzae) of perennial ryegrass (Lolium perenne) is discussed in detail, including the disease's symptoms and signs, host range, taxonomy, and geographic distribution, as well as methods of isolation, identification, and storage of M. oryzae.

Accepted for publication 29 January 2003. Published 10 March 2003.
First Report of Pepper mild mottle virus in Jalapeno Pepper in Georgia
Authors: Martínez-Ochoa Natalia , Langston David B. , Mullis Stephen W. , Flanders James T.
Published: May 2008

In October of 2002, an entire field of jalapeno pepper in Grady County, Georgia was affected by a virus-like disease. All fruit and leaf tissues and seed samples tested positive for Pepper mild mottle virus (PMMoV). Transmission through both seed and sap inoculation was confirmed under greenhouse conditions. This is the first report of seed-transmitted PMMoV affecting jalapeno peppers in Georgia.

Accepted for publication 3 November 2003. Published 23 December 2003.
First Report of Plasmopara halstedii on Perennial Black-Eyed Susan in North Florida
Authors: Dankers Hank , Kimbrough James W. , Momol M. Timur
Published: May 2008

In August 2003, the Florida Extension Plant Diagnostic Clinic in Quincy, FL, received a perennial black-eyed-susan (orange coneflower) plant exhibiting symptoms of downy mildew. Nearly all of approximately 0.2 hectares of potted plants grown by a nursery were symptomatic. Downy mildew has not been previously reported on perennial black-eyed-susan in Florida.

Accepted for publication 2 January 2004. Published 19 January 2004.
Characterization of Pythium spp. from Three Ohio Fields for Pathogenicity on Corn and Soybean and Metalaxyl Sensitivity
Authors: Dorrance A. E. , Berry S. A. , Lipps P. E.
Published: May 2008

Pythium spp. were baited with corn and soybean seed from soils collected from three locations in Ohio where soybean and corn stand establishment was a concern. Five species, P. catenulatum, P. irregulare, P. paroecandrum, P. splendens, and P. torulosum, were recovered and a subset of these isolates was then tested for pathogenicity on corn and soybean seed and sensitivity to the seed treatment fungicide metalaxyl. There was a range of both pathogenicity and sensitivity to metalaxyl within and among the Pythium spp. recovered from the three locations. A more thorough evaluation of the Pythium populations that exist in grain production fields in the north central region of the US is needed to facilitate the development and deployment of broader based seed treatment products.

Accepted for publication 12 January 2004. Published 2 February 2004.
Transgenic Rootworm Corn: Assessing Potential Agronomic, Economic, and Environmental Benefits
Authors: Rice Marlin E.
Published: May 2008

The potential benefits of transgenic rootworm corn (Cry3Bb1 protein) are expected to include: increased root protection; increased intangible benefits to farmers (safety of not being exposed to insecticides, ease of use and handling, time and labor savings, better pest control); increased economic benefits to farmers ($231 million from yield gains [$25-$75/acre relative to no insecticide control, $4-$12/acre relative to control with a soil insecticide] and $58 million in reduced insecticide risks and time savings); reduced incidence of corn stalk rot; and increased yield protection (9 to 28% relative to no insecticide use, 1.5 to 4.5% relative to control with a soil insecticide). If transgenic rootworm corn is planted on 10 million acres, the annual impact will be a reduction of 5,344,462 lb a.i. (75.2%) of insecticide use; increased resource conservation (3.07 to 5.23 million gal of diesel fuel equivalents conserved that would have been consumed in the manufacture and delivery of insecticides); increased water conservation (5,657,734 gal of water not used in insecticide application); conservation of aviation fuel (68,845 gal of aviation fuel not used); reduced farm waste (1,187,035 fewer insecticide containers used); increased planting efficiency; and improved safety to wildlife and other nontarget organisms.

Accepted for publication 1 February 2004. Published 1 March 2004.
Trionymus haancheni McKenzie: A New Pest of Barley in Idaho
Authors: Alvarez Juan M.
Published: May 2008

A new insect pest of barley, sometimes referred to as the Haanchen barley mealybug, was discovered for the first time in Idaho near Soda Springs during June 2003 in a commercial barley field. This report is the first documented detection of T. haancheni in Idaho. It summarizes what is known about T. haancheni from the published literature, field surveys in Idaho, and laboratory observations.

Accepted for publication 11 February 2004. Published 15 March 2004.
First Report of Powdery Mildew of Akebia quinata Caused by Microsphaera akebiae (Erysiphe akebiae) in North America
Authors: Glawe Dean A. , Glass Jenny R.
Published: May 2008

Akebia quinata (chocolate-vine, five-leaf akebia) is grown as a perennial ornamental vine in North America. Five collections were made from A. quinata plants in western Washington with symptoms of powdery mildew caused by Microsphaera akebiae Sawada. This report documents the presence of this fungus in North America for the first time, describes and illustrates this fungus and the disease it causes, and reviews the taxonomy and identification of the fungus.

Accepted for publication 24 February 2004. Published 16 March 2004.
First Report of White Rust of Lunaria annua Caused by Albugo candida in North America
Authors: Glawe Dean A. , Glass Jenny R. , Putnam Melodie L.
Published: May 2008

Lunaria annua, or money plant, is grown as an ornamental landscape plant and is used in dried flower arrangements. This report provides the first documentation of white rust (caused by the fungus Albugo candida) on L. annua in North America, and describes the symptoms and morphology of A. candida useful for identification.

Accepted for publication 24 February 2004. Published 17 March 2004.
Fusarium Species Associated with Tall Fescue Seed Production in Oregon
Authors: Ocamb Cynthia M. , Alderman Stephen C.
Published: May 2008

Seed samples were collected from 15 commercial tall fescue seed production fields and examined for Fusarium spp. The percentage of seeds from which Fusarium spp. were recovered ranged from 0 to 32%, while disinfesting seeds with 3% hydrogen peroxide reduced the recovery of Fusarium to 7% or less. The predominant Fusarium spp. isolated from the tall fescue seeds included F. avenaceum, F. culmorum, F. pseudograminearum, and F. sambucinum. Greenhouse inoculations of tall fescue panicles with F. avenaceum, F. culmorum, and F. pseudograminearum resulted in higher seedborne rates of each respective Fusarium sp. than that recovered from noninoculated plants. Seeds recovered from panicles treated with F. avenaceum or F. pseudograminearum had significantly lower germination rates relative to panicles sprayed with water or a suspension of F. culmorum. Our work confirms that Fusarium spp. decrease seed germination and expands the pathogen list to include F. avenaceum and F. pseudograminearum.

Accepted for publication 17 February 2004. Published 19 March 2004.
Discrimination of Plant Pathogenic Bacteria Using an Electronic Nose
Authors: Momol M. T. , Balaban M. O. , Korel F. , Odabasi A. , Momol E. A. , Folkes G. , Jones J. B.
Published: May 2008

An electronic nose (EN) is an array of chemical sensors, where each sensor has only fractional specificity to a wide range of odor molecules, connected with a suitable pattern recognition system. A rapid, sensitive, specific, nondestructive, and easy-to-use technique such as the EN could be used to detect and identify plant pathogenic bacteria in diagnostic clinics and quarantine labs. In this study, an EN discriminated between plant pathogenic bacteria belonging to up to seven species from seven different genera.

Accepted for publication 31 March 2004. Published 5 April 2004.
The Response of Fusarium graminearum-Infected Seed of Hard Red Spring Wheat to Vitavax Extra RTU and Dividend XL Seed Treatments
Authors: Wiersma Jochum J. , Kandel Herman J.
Published: May 2008

Fusarium head blight (FHB) caused by Fusarium graminearum can severely impact seed quality and limit the availability of seed. Repeated outbreaks of FHB in the hard red spring wheat (HRSW) production areas of Minnesota and North Dakota since 1993 has forced seed dealers and producers, on occasion, to use FHB-infected wheat as seed. In this experiment, two FHB-infected seed lots, one of the variety Verde and one of the variety 2375, were used to determine the effect of Vitavax Extra RTU (16.7% carboxin : 1.2% imazalil : 1.5% thiabendazole) and Dividend XL (16.5% difenoconazole : 1.38% mefenoxam) on initial plant population, grain yield, and quality. The standard laboratory germination tests indicated that germination of Vitavax Extra RTU-treated seed increased germination from 64 to 84% for both seed lots. Using a four-by-two factorial design, the effect of the brand of seed treatment, the effect of using either brand of seed treatment versus not using a seed treatment at all, and the attained germination percentages from the laboratory tests were used to determine the effects on the initial plant population, grain yield, test weight, and grain protein content. In three field trials, there was no significant interaction between the use of either Vitavax Extra RTU or Dividend XL and seeding rate for initial plant population, grain yield, and test weight. Although a treatment of FHBinfected wheat seed with Vitivax Extra RTU increased germination in a laboratory test, there was no increase in initial plant population or grain yield and quality compared to untreated seed. However, increasing the seeding rate in field trials compensated for poor germination results in the laboratory test and resulted in higher initial stands. Consequently, results of the laboratory test of the untreated seed needed to be used to calculate a proper seeding rate for both seed lots.

Accepted for publication 2 April 2004. Published 16 April 2004.
First Report of Powdery Mildew of Myosotis sylvatica (Wood Forget-me-not) Caused by Golovinomyces cynoglossi (Erysiphe cynoglossi) in Washington State
Authors: Glawe Dean A.
Published: May 2008

Wood forget-me-not cultivars are popular ornamentals in the Pacific Northwest. In western Washington, this species frequently displays symptoms and signs of powdery mildew after anthesis. This report records the disease from King, Pierce, Snohomish, and Skagit counties and describes and illustrates symptoms of the disease as well as taxonomically important features of the causal organism.

Accepted for publication 29 October 2004. Published 24 November 2004.
First Report of Powdery Mildew of Lycium chinense (Chinese Matrimony Vine) Caused by Arthrocladiella mougeotii in the Pacific Northwest
Authors: Glawe Dean A.
Published: May 2008

Chinese matrimony-vine (Lycium chinense Mill.) is a traditional medicinal plant grown in China and used as a perennial landscape plant in North America. This report documents the presence of powdery mildew on L. chinense in the Pacific Northwest and describes and illustrates morphological features of the causal agent. It appears to be the first report of a powdery mildew caused by Arthrocladiella in the Pacific Northwest.

Accepted for publication 10 November 2004. Published 8 December 2004.
First Report of Powdery Mildew of Carrot and Parsley Caused by Erysiphe heraclei in Washington State
Authors: Glawe Dean A. , Pelter Gary Q. , Toit Lindsey J. du
Published: May 2008

From 2002 to 2004, the anamorph of Erysiphe heraclei DC was observed on plants from processing carrot fields in central WA. The teleomorph, not previously reported in Washington, was discovered in a processing carrot field in Grant Co. A fungus matching the description of the anamorph of E. heraclei also was found attacking parsley in a home garden in Grant Co. This report documents the occurrence of E. heraclei and its teleomorph on carrot in WA and the occurrence of E. heraclei on parsley in WA.

Accepted for publication 10 January 2005. Published 14 January 2005.
Diagnosis of Trichodorus obtusus and Paratrichodorus minor on Turfgrasses in the Southeastern United States
Authors: Crow William T.
Published: May 2008

“Stubby-root” nematodes are of agricultural importance as plant-pathogens and as vectors for plant viruses. Two species of stubby-root nematode have been identified as pathogens on warm-season turfgrasses in the southern U.S.: Paratrichodorus minor and Trichodorus obtusus. Both are pathogens of bermudagrass and St. Augustinegrass, with T. obtusus more damaging than P. minor. Methods for distinguishing these species are described that do not require mounting of specimens and can be used at ×100 magnification or less.

Accepted for publication 24 November 2004. Published 21 January 2005.
First Report of Stripe Rust caused by Puccinia striiformis f. sp. tritici on Wheat in Florida
Authors: Blount Ann R. , Rizvi Shabbir A. , Barnett Ronald D. , Chen Xianming , Schubert Timothy S. , Dankers W. Hank , Momol Timur M. , Dixon Wayne N.
Published: May 2008

The wheat stripe rust pathogen occured on several experimental wheat lines planted at Quincy, FL in early February 2003. Several experimental lines in the 2003 Advanced Wheat A, the Advanced Wheat B, and the Uniform Southern Wheat Nursery yield trials then showed traces of stripe rust on the leaves of the plants. An unusually cool and wet winter and spring encouraged a scattered outbreak of stripe rust of wheat on susceptible experimental lines of wheat. This report constitutes the first documented case of stripe rust of wheat in Florida.

Accepted for publication 22 February 2005. Published 4 March 2005.
Comparing Diagnostic Protocols for Phytophthora ramorum in Rhododendron Leaves
Authors: Osterbauer Nancy , Trippe Aaron
Published: May 2008

Phytophthora ramorum attacks many plant species important to the nursery industry and to the natural environment. USDA-APHIS requires all West Coast nursery stock to be inspected and, if necessary, tested for P. ramorum prior to export. The plants must be tested using a commercial DAS-ELISA kit and, if confirmed positive, the species-specific methods of PARP and PCR. This paper compares these diagnostic methods for the detection of P. ramorum in Rhododendron (L.) nursery stock.

Accepted for publication 4 March 2005. Published 14 March 2005.
Use of Petroleum Derived Spray Oils in Washington Grapevine Powdery Mildew Management Programs
Authors: Grove G. G. , Lunden J. , Spayd S.
Published: May 2008

The effects of petroleum-derived spray oils (PDSO) on powdery mildew control and selected berry characteristics were evaluated in vineyards in eastern Washington during 2001 and 2002. Up to seven PDSO applications were made during each growing season between the 15-to-30-cm shoot stage and veraison. The use of oil decreased total soluble solids (TSS) at harvest by 0.17% per application but had no significant effects on berry weight, pH, or titratable acidity. Because of their documented eradicant and antisporulant properties, PDSO were also utilized as the initial treatment in fungicide treatment sequences initiated upon the first visual detection of powdery mildew signs in the vineyard. When used in this fashion very early in powdery mildew epidemics, PDSO helped to reduce fungicide usage and input costs without compromising disease control.

Accepted for publication 15 February 2005. Published 17 March 2005.
Effects of Azoxystrobin Application Rate and Treatment Interval on the Control of Rhabdocline pseudotsugae on Douglas-fir Christmas Trees
Authors: Bates Ricky M. , Despot David A.
Published: May 2008

Rhabdocline needlecast caused by Rhabdocline pseudotsugae is the primary disease limiting Douglas-fir Christmas tree production in the northeastern United States. Azoxystrobin (Quadris) was recently registered for control of needlecasts on conifers, but little is known about its efficacy. In 2002, azoxystrobin was applied to field-grown Lincoln N.F. Douglas-fir Christmas trees at 0.14 or 0.28 g a.i./liter as the first or second spray of a chlorothalonil-based control program. In 2003, four sequential sprays of azoxystrobin at 0.28, 0.55, and 1.10 g a.i./liter were compared to chlorothalonil treatments. Untreated trees at both Pennsylvania test sites in both years were heavily infected, confirming high inoculum levels and environmental conditions favorable for infection. The standard program that consisted of 1.29 g a.i./liter chlorothalonil applications was very effective in controlling Rhabdocline in all experiments. In 2002, application interval had a significant effect on efficacy. Trees sprayed with 0.14 and 0.28 g a.i./liter azoxystrobin 9 days prior to an infection period had a higher disease index rating than those sprayed 2 days prior to the same infection period. Application rate did not appear to have an effect on efficacy. Trees receiving 1.10 g a.i./liter azoxystrobin had the same disease index rating as trees receiving the 0.28 g a.i./liter rate. In all cases, azoxystrobin treatments had significantly higher infection rates than the standard chlorothalonil treatment. The level of natural inoculum present at each site also appeared to play a role in azoxystrobin efficacy. Azoxystrobin is more than twice the cost of chlorothalonil and the data presented does not support any cost incentive for its inclusion in a Rhabdocline control program.

Accepted for publication 19 May 2005. Published 17 June 2005.
The Southeastern U.S. Fusarium Head Blight Epidemic of 2003
Authors: Cowger Christina , Sutton Abbey L.
Published: May 2008

Fusarium head blight (FHB) caused unprecedented losses to southeastern U.S. wheat producers and millers in 2003. The epidemic was documented afterward through interviews with 120 researchers, extension agents, millers, and growers. Sixty-two counties in five states were assigned an FHB impact score of 1 to 4, and 2003 yield and weather data were obtained for those counties. The relationships of yield and pre- and post-flowering weather variables to impact score were evaluated using regression and correlation analyses. Yield as a percentage of the 10-year average was negatively correlated with FHB impact (r = -0.588, P < 0.0001). FHB impact was positively correlated with hours of post-flowering rainfall (r = 0.465, 0.590, and 0.619 for 10, 20, and 30 days post-flowering, respectively; P = 0.0001), but not correlated with hours of pre-flowering rainfall (P = 0.99). While this was not a controlled study, the results suggest that pre-flowering weather may have played a less significant role than post-flowering weather, and was unlikely to have been a good predictor of FHB severity in the southeast in 2003. Using 10-year average production data, premilling economic losses were estimated for 40 counties in Maryland, Virginia, and North Carolina at over $13.6 million. Wheat production in those counties comprised just 71.7%, 45.8%, and 48.0% of the statewide totals, respectively; thus, actual 2003 FHB-related losses to growers in those states were probably much higher. Additionally, mills in the region suffered losses of several million dollars in 2003 due to increased shipping, testing, and handling costs brought on by FHB.

Accepted for publication 26 September 2005. Published 26 October 2005.
Repellency and Repulsiveness of Selected Agrichemicals to the Two-Spotted Spider Mite (Tetranychus urticae) on Grape Foliage
Authors: Walsh Douglas B. , Grove Gary G.
Published: May 2008

Leaf disk and whole leaf bioassays were conducted to evaluate the repellency and repulsiveness of selected fungicides, insecticides, spray adjuvants, and petroleum-derived spray oils (PDSO) to the two-spotted spider mite, Tetranychus Urticae Koch (Acari: Tetranychidae). Compounds were evaluated for their ability to stimulate the movement of T. urticae from treated to nontreated grape tissue (repellency) and to inhibit their movement from untreated to treated tissue (repulsiveness). All insecticides other than Bacillus thuringiensis and some fungicides were highly repellent. Several insecticides and fungicides, and all spray adjuvants, were highly repulsive. We conclude that many agrichemicals are irritating to two-spotted spider mites and may impact their spatial dynamics within plant canopies.

Accepted for publication 7 November 2005. Published 28 December 2005.
Relative Distribution and Incidence of Viruses Associated with Disease Outbreaks in Tomato Fields in Trinidad
Authors: Rampersad S. N.
Published: May 2008

Tomato production in Trinidad has suffered considerable losses in yield and fruit quality due to infections of hitherto surmised etiology. In order to develop strategies for controlling viral diseases in tomato, the relative distribution and incidence of seven viruses that commonly infect tomato were determined. Of the 362 samples tested, Potato yellow mosaic Trinidad virus (PYMTV) was found in every farm except two and was present at relatively high incidence throughout the country. Tobacco mosaic virus (TMV) and Tobacco etch virus (TEV) were found in fewer farms and at lower incidences while the other viruses were absent. Single infections of either virus were more common than double infections and multiple infections were rare but present. The results indicated that PYMTV is the predominant and most important viral pathogen in tomato production systems in Trinidad; however, begomovirus disease management strategies will also have to accommodate controls

Accepted for publication 10 January 2006. Published 9 March 2006.
Susceptibility of Camellia to Phytophthora ramorum
Authors: Shishkoff Nina
Published: May 2008

Camellia is a known host of Phytophthora ramorum, the “sudden oak death” pathogen. During 2003-2004, the organism was shipped from California throughout the U.S. on infected nursery stock, leading to a nationwide effort to recover the infected plants. This paper describes the symptoms on Camellia and the relative susceptibility of nine species and four hybrids. Camellias varied widely in susceptibility, with Camellia × ‘Roni gaki’ showing the worst overall symptoms, while some other cultivars showed little or none. Obvious symptoms include leaf lesions and stem blight; defoliation, while more difficult to observe, was also characteristic in camellias. The pathogen persisted in diseased plants, notably in stem tissue, for at least a month as demonstrated by isolation. One month after inoculation, roots remained

Accepted for publication 23 December 2005. Published 15 March 2006.
Control of Phytophthora Root Rot in Field Plantings of Fraser Fir with Fosetyl-Al and Mefenoxam
Authors: Benson D. M. , Sidebottom J. R. , Moody J.
Published: May 2008

Fungicides were evaluated for control of Phytophthora root rot for five growing seasons in two field plantings of Fraser fir (Abies fraseri) affected by Phytophthora cinnamomi in western North Carolina. At the first site, which had a fairly well-drained soil, treatment programs with Aliette (5 lb/100 gal, three applications per year), Subdue Maxx (3.7 fl oz/1.15 gal/1000 ft2, two applications per year), and Subdue GR (5.75 lb/1000 ft2, two applications per year) maintained low rates of mortality (< 10%) for three growing seasons, whereas tree mortality in the untreated plots reached 13 and 37% by the second and third growing seasons, respectively. At the second site, which was in a flood plain, disease did not develop during the first 2.5 years, even in untreated control plots. However, mortality increased rapidly following several high-rainfall events, but none of the fungicides had any effect on disease development. Apparently, at least under conditions not overly conducive to the disease, the fungicide treatment programs can delay the onset of high mortality rates caused by P. cinnamomi in Fraser fir for up to three growing seasons.

Accepted for publication 23 February 2006. Published 31 March 2006.
Effect of Two Different Nozzle Arrangements on Control of Carrot Weevil, Listronotus oregonensis (LeConte), in Processing Carrots
Authors: Ghidiu Gerald M. , Hitchner Erin , Zimmerman Melissa , Rossell Elwood
Published: May 2008

Field studies were conducted during 2004-2005 at the Rutgers Agricultural Research and Extension Center, Bridgeton, NJ to determine the effect of two different nozzle arrangements on the control of the carrot weevil, Listronotus oregonensis (LeConte), in processing carrots (Daucus carota L.). Two drop nozzles per row directed at the base of the plant resulted in significantly fewer damaged carrots caused by carrot weevil feeding each year as compared with a single nozzle centered as a 15.2-cm band located 30.5 cm over the row. However, carrot weevil damage to carrots was high each year in all treatments even during and after multiple pesticide applications, suggesting that growers need to use other management tactics with their spray program. Crop rotation, weed control, and planting date may be as important as pesticide selection and application for effective management of the carrot weevil.

Accepted for publication 7 February 2006. Published 3 April 2006.
Incidence of Alfalfa mosaic virus, Bean pod mottle virus, and Soybean mosaic virus in Nebraska Soybean Fields
Authors: Giesler Loren J. , Ziems Amy D.
Published: May 2008

The incidence of soybean viruses is increasing across the North Central Region of the United States as indicated by survey efforts and grower reports from several states. To determine the level of virus infection in Nebraska, we surveyed soybean fields for two consecutive years. Alfalfa mosaic virus (AMV) was detected in 52% of the fields in 2001 and in 56% of fields in 2002. The incidence of Bean pod mottle virus (BPMV) varied more, with 54% of fields testing positive in 2001 and 91% testing positive in 2002. Soybean mosaic virus (SMV) was not detected in 2001, but it was detected in 31% of fields in 2002. The widespread distribution of detected SMV in 2002 is suggestive of introduction with seed. The incidence of BPMV was significantly higher in fields planted earlier than the recommended optimum planting date in one of the two years studied. The widespread incidence of AMV and BPMV and the irregular occurrence of SMV indicate that further studies of soybean viral diseases in Nebraska are warranted.

Accepted for publication 13 March 2006. Published 24 April 2006.
Early Detection of Asian Soybean Rust Using PCR
Authors: Lamour Kurt H. , Finley Ledare , Snover-Clift Karen L. , Stack James P. , Pierzynski Joy , Hammerschmidt Ray , Jacobs Janette L. , Byrne Janet M. , Harmon Philip F. , Vitoreli Anne M. , Wisler Gail C. , Harmon Carrie L. , Levy Laurene , Zeller Kurt A. , Stone Christine L. , Luster Douglas G. , Frederick Reid D.
Published: May 2008

Early detection of Asian soybean rust (ASR) is essential to help producers minimize the impact of this serious disease. DNA from ASR-infected soybean plants was used to compare conventional and real-time ASR-specific PCR assays at seven laboratories in the United States. Soybean plants were inoculated with four concentrations of rust spores to establish different levels of infection within the plants. Plant tissue was then harvested at 7 time points over the course of 12 days, and DNA was extracted using two commercially available kits. DNA extracted from soybean plants inoculated with different spore concentrations was tested for ASR using conventional or real-time PCR assays. ASR was consistently detected at 6 days following inoculation with both the conventional and real-time PCR assays. This study demonstrates the ability to reliably detect ASR in soybean before the presence of readily visible symptoms. It also demonstrates the reproducibility of the PCR assay across different real-time PCR platforms at multiple laboratories when the assays were performed in multiple diagnostic laboratories.

Accepted for publication 5 April 2006. Published 24 May 2006.
Sclerotinia Blight in Georgia and Evidence for Resistance to Sclerotinia sclerotiorum in Runner Peanuts
Authors: Woodward Jason E. , Brenneman Timothy B. , Kemerait Robert C. , Culbreath Albert K. , Clark James R.
Published: May 2008

Sclerotinia blight (Sclerotinia sclerotiorum (Lib.) de Bary) was recently identified in a commercial peanut (Arachis hypogaea L.) field in Appling County, GA. Symptoms were first observed on the cultivars Tifrunner and Georgia 02C. Plant inoculations and a detached leaflet assay were conducted to determine the susceptibility of the cultivars Georgia Green, Georgia 02C, Georgia 03L, AP-3, Georgia 01R, Hull, C-99R, and Tifrunner. For plant inoculations, lesion lengths were greatest for Okrun, the susceptible control, and Georgia 02C; lesion lengths for C-99R and Georgia 01R did not differ significantly from Tamspan 90, the resistant control. Georgia Green, the current commercial standard, exhibited intermediate lesion lengths. Similar results were obtained from the detached leaflet assay. These results suggest that differing levels of resistance to S. sclerotiorum are available in runner cultivars used in the southeastern United States.

Accepted for publication 27 March 2006. Published 31 May 2006.
First Report of Powdery Mildew on Dipsacus sylvestris Caused by Sphaerotheca dipsacearum in North America
Authors: Dugan Frank M. , Glawe Dean A.
Published: May 2008

Common teasel (Dipsacus sylvestris) is a European species introduced into North America, and is now widely established and regarded as a noxious weed. In October 2005, a powdery mildew was observed on D. sylvestris in two locations in Pullman, Whitman Co., WA. Examination of diseased material confirmed that the causal agent was S. dipsacearum. This report provides the first documentation of S. dipsacearum on D. sylvestris in North America.

Accepted for publication 20 April 2006. Published 7 June 2006.
First Report of Tomato spotted wilt virus in Tomatillo in Florida
Authors: Adkins Scott , Momol M. Timur , Dankers Hank , Reitz Stuart , Olson Stephen
Published: May 2008

In the spring of 2004 and 2005, symptoms similar to those induced by the thrips-vectored Tomato spotted wilt virus (TSWV) were observed on tomatillo in cultivated fields in Gadsden county and experimental plots in Leon county, both in northern Florida. Presence of TSWV was confirmed. To the best of our knowledge this is the first report of TSWV on tomatillo in Florida.

Accepted for publication 8 May 2006. Published 7 June 2006.
Toxicity and Field Efficacy of Acetamiprid on Asparagus Beetle
Authors: Kuhar Thomas P. , Doughty Helene B. , Hitchner Erin M. , Chapman Anna V.
Published: May 2008

The asparagus beetle, Crioceris asparagi L., is a major pest of asparagus in the United States. Commercial growers typically apply a foliar insecticide in the spring to kill adults before they can oviposit on asparagus spears. However, very few new insecticides have been registered on the crop in the last twenty years, and many chemicals have lost their registrations due to enactment of the Food Quality Protection Act. Laboratory and field experiments were conducted to evaluate the efficacy of a novel neonicotinoid insecticide, acetamiprid, to control all life stages of the asparagus beetle. Laboratory toxicity assays revealed that acetamiprid is highly toxic to asparagus beetle eggs and larvae. LC50 levels were 8.95 mg ai/liter for eggs and 0.012 mg ai/liter for larvae. Field efficacy trials in Virginia showed that acetamiprid applied at 0.112 kg ai/ha significantly reduced the numbers of asparagus beetle adults, eggs, and larvae on asparagus equal to or greater than that of the insecticide standard, methomyl. Acetamiprid also provided excellent control of aphids on spears, equal to or greater than that of methomyl.

Accepted for publication 3 May 2006. Published 18 August 2006.