Index Catalog // ScholarsArchive@OSU

Powdery Mildew Caused by Podosphaera macularis on Hop (Humulus lupulus) in North Carolina

Creator:: Wolfenbarger, S. N., Quesada-Ocampo, L. M., and Gent, D. H.
Abstract:: Hop (Humulus lupulus L.) production recently has expanded across the United States to include areas of the country that have not previously grown hop commercially. In June 2015, a grower in western North Carolina detected powdery mildew in a small (<0.5-ha) yard during routine scouting. Characteristic signs of powdery mildew...
Resource Type:: Article

Black Wilt of Hop (Humulus lupulus) Caused by Diplodia seriata in New York State

Creator:: Twomey, M. C., Stone, J. K., and Gent, D. H.
Abstract:: In August 2012, wilted hop bines were observed in a yard near Seneca Castle, New York, affecting 10 to 20% of the plants. Affected bines had a dark stem discoloration and wilted leaves that remained attached after bines were killed. Dark brown to black, erumpent pycnidia were aggregated in the...
Resource Type:: Article

Genotyping-by-sequencing of a bi-parental mapping population segregating for downy mildew resistance in hop (Humulus lupulus L.)

Creator:: Henning, J. A., Gent, D. H., Twomey, M. C., Townsend, M. S., Pitra, N. J., and Matthews, P. D.
Abstract:: Downy mildew (caused by Pseudoperonospora humuli) causes significant losses in hop (Humulus lupulus L.) cone yield and quality, and potential crown death. Breeding for resistance has proved difficult presumably because of the highly quantitative nature of genetic control over expression. The objective of this study was to utilize multiple environments...
Resource Type:: Article

Identification and distribution of mating-type idiomorphs in populations of Podosphaera macularis and development of chasmothecia of the fungus

Creator:: Wolfenbarger, S. N., Twomey, M. C., Gadoury, D. M., Knaus, B. J., Grünwald, N. J., and Gent, D. H.
Abstract:: Podosphaera macularis, the causal agent of hop powdery mildew, is known to produce chasmothecia (formerly cleistothecia) in eastern North America and Europe. Ascocarps have not yet been reported from the Pacific Northwestern region of North America. Reasons for the apparent absence of chasmothecia in the Pacific Northwest were unknown. This...
Resource Type:: Article

Precision QTL mapping of downy mildew resistance in hop (Humulus lupulus L.)

Creator:: Henning, J. A., Gent, D. H., Twomey, M. C., Townsend, M. S., Pitra, N. J., and Matthews, P. D.
Abstract:: Hop downy mildew (DM) is an obligate parasite causing severe losses in hop if not controlled. Resistance to this pathogen is a primary goal for hop breeding programs. The objective of this study was to identify QTLs linked to DM resistance. Next-generation-sequencing was performed on a mapping population segregating for...
Resource Type:: Article

Thrips tabaci (Thysanoptera: Thripidae) and Iris yellow spot virus Associated with Onion Transplants, Onion Volunteers, and Weeds in Colorado

Creator:: Schwartz, H. F., Gent, D. H., Fichtner, S. M., Otto, K., Boateng, C. O., Szostek, S., Cranshaw, W. S., and Mahaffey, L. A.
Abstract:: Infestation by onion thrips, Thrips tabaci Lindeman, was determined on transplants of onion (Allium cepa L.) received in Colorado during March and April from out-of-state sources (Imperial Valley, CA; near Phoenix, AZ; and southern Texas) during 2004 to 2008. In the 5 years of the study, 50 to 100% of...
Resource Type:: Article

Suppression of Hop Looper (Lepidoptera: Noctuidae) by the Fungicide Pyraclostrobin

Creator:: Woods, J. L. and Gent, D. H.
Abstract:: The hop looper, Hypena humuli Harris, is a reemergent pest of hop that often requires treatment to mitigate crop damage. In 4 yr of field trials, plots treated with fungicides were observed to sustain less hop looper defoliation compared with nontreated plots. Further investigation revealed that abundance of hop looper...
Resource Type:: Article

Development of Biological Control of Tetranychus urticae (Acari: Tetranychidae) and Phorodon humuli (Hemiptera: Aphididae) in Oregon Hop Yards

Creator:: Woods, J. L., Dreves, Amy J., James, D. G., Lee, J. C., Walsh, D. B., and Gent, D. H.
Abstract:: The temporal development of biological control of arthropod pests in perennial cropping systems is largely unreported. In this study, the development of biological control of twospotted spider mite, Tetranychus urticae Koch, and hop aphid, Phorodon humuli (Schrank), in a new planting of hop in Oregon is described over a period...
Resource Type:: Article

Crop damage caused by powdery mildew on hop and its relationship to late season management

Creator:: Gent, D. H., Grove, G. G., Nelson, M. E., Wolfenbarger, S. N., and Woods, J. L.
Abstract:: Powdery mildew of hop (Podosphaera macularis) may cause economic loss due to reductions in cone yield and quality. Quantitative estimates of crop damage from powdery mildew remain poorly characterized, especially the effect of late season disease management on crop yield and quality. Field studies in Washington State evaluated cone yield,...
Resource Type:: Article

Sclerotinia Wilt of Hop (Humulus lupulus) Caused by Sclerotinia sclerotiorum in the Pacific Northwest United States

Creator:: Kropf, S. M., Putnam, M. L., Serdani, M., Twomey, M. C., Woods, J. L., and Gent, D. H.
Abstract:: In June 2009, wilted hop bines were observed in a yard in Marion County, OR. The wilt was associated with a stem rot that occurred ∽1 m from the ground near the point where bines are tied together for horticultural purposes. Samples of affected stems were submitted to the Oregon...
Resource Type:: Article

Sensitivity of Disease Management Decision Aids to Temperature Input Errors Associated with Sampling Interval and Out-of-Canopy Sensor Placement

Creator:: Pfender, W. F., Gent, D. H., and Mahaffee, W. F.
Abstract:: Many plant disease epidemic models, and the disease management decision aids developed from them, are created based on temperature or other weather conditions measured in or above the crop canopy at intervals of 15 or 30 min. Disease management decision aids, however, commonly are implemented based on hourly weather measurements...
Resource Type:: Article

Comments Regarding the Binary Power Law for Heterogeneity of Disease Incidence

Creator:: Turechek, W. W., Madden, L. V., and Gent, D. H.
Abstract:: The binary power law (BPL) has been successfully used to characterize heterogeneity (overdispersion or small-scale aggregation) of disease incidence for many plant pathosystems. With the BPL, the log of the observed variance is a linear function of the log of the theoretical variance for a binomial distribution over the range...
Resource Type:: Article

ScholarsArchive@OSU

Powdery Mildew Caused by Podosphaera macularis on Hop (Humulus lupulus) in North Carolina

Black Wilt of Hop (Humulus lupulus) Caused by Diplodia seriata in New York State

Genotyping-by-sequencing of a bi-parental mapping population segregating for downy mildew resistance in hop (Humulus lupulus L.)

Identification and distribution of mating-type idiomorphs in populations of Podosphaera macularis and development of chasmothecia of the fungus

Precision QTL mapping of downy mildew resistance in hop (Humulus lupulus L.)

Thrips tabaci (Thysanoptera: Thripidae) and Iris yellow spot virus Associated with Onion Transplants, Onion Volunteers, and Weeds in Colorado

Suppression of Hop Looper (Lepidoptera: Noctuidae) by the Fungicide Pyraclostrobin

Development of Biological Control of Tetranychus urticae (Acari: Tetranychidae) and Phorodon humuli (Hemiptera: Aphididae) in Oregon Hop Yards

Crop damage caused by powdery mildew on hop and its relationship to late season management

Sclerotinia Wilt of Hop (Humulus lupulus) Caused by Sclerotinia sclerotiorum in the Pacific Northwest United States

Sensitivity of Disease Management Decision Aids to Temperature Input Errors Associated with Sampling Interval and Out-of-Canopy Sensor Placement

Comments Regarding the Binary Power Law for Heterogeneity of Disease Incidence

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