Hop looper, Hypena humuli Harris, can cause substantial defoliation and crop damage by feeding on hop leaves and cones. A 4-yr field study conducted in western Oregon evaluated the abundance of hop looper larvae and associated defoliation of leaves on plants fertilized with nitrogen rates ranging from 44.8 to 269...
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...
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...
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...
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...
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...
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...
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,...
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...
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...