Narrative
In response to requests from the ornamental nursery industry, the Agricultural Research Service (ARS) and the Agricultural Experiment Station of Oregon State University have released a new ornamental hop, 'SCARLET' (USDA accession number 21741). SCARLET is more vigorous than its' female parent 'Blue Northern Brewer', is moderately resistant to downy mildew (Pseudoperonospora humuli (Miy. et. Tak., G.W. Wilson), and has increased resistance to the two-spotted spider mite (Tetranichus urticae (Koch). SCARLET, a female plant, originated from a cross made by USDA hop geneticist Alfred Haunold between 'Blue Northern Brewer' (USDA 21079) and the USDA male 21329M. Blue Northern Brewer is thought to have originated from 'Northern Brewer' (USDA 64107) but no specific information was provided when it was introduced through germplasm exchange from Belgium in 1974. The male parent, USDA 21329, was developed from a cross between 'Comet' (USDA 62013) and the male USDA 21111M. Assuming Blue Northern Brewer is a mutation of Northern Brewer, the genetic composition of SCARLET is 1/2 `Northern Brewer?, 1/4 Comet, 1/8 'Bullion', 1/32 Hallertauer `Mittlefrueh?, and 3/32 unknown. The original cross from which SCARLET originated was made in 1994, and the initial selection number was 9418-44. A single hill was established in the USDA-ARS hop nursery near Corvallis, Oregon in 1995. Evaluation of quality and agronomic characteristics was initiated in 1996, but due to personnel turnover in the hop program beginning in 1996, evaluations were not completed until 2005. Three years of chemical content and five years of agronomic data have been collected. SCARLET grows quickly and routinely reaches the top trellis wire (18 feet, 5.5 m) in western Oregon whereas Blue Northern Brewer does not. SCARLET is very similar to Blue Northern Brewer in appearance and is characterized by leaves that are often 3-lobed and exhibit a dark blue-green color, dark purple stems, and a reddish tinge to the cones. Side-arms are very short and foliage is relatively sparse compared to typical hop cultivars used for commercial production. Flowering occurs in early July and ploidy is diploid (2n=2x=20). Although SCARLET is intended as an ornamental, limited cone yield and chemical data were collected to help characterize the genotype. SCARLET contains approximately the same amount of alpha acid (3-year average = 5.99% v/v) but slightly less beta acid (3-year average = 1.45% v/v) than Blue Northern Brewer (alpha = 6.1% v/v, beta = 2.5% v/v) . As a result, the alpha-ratio (Alpha % / (Alpha % + Beta % = 83) of SCARLET is slightly higher than the alpha-ratio of Blue Northern Brewer (alpha ratio = 71). Hop storage index over 3 years was 0.29 while cohumulone content was measured at 27 % (v/v). SCARLET exhibits some symptoms of downy mildew infection in the spring but quickly recovers to produce healthy foliage. Based on five years of field observations, SCARLET is considered moderately resistant to downy mildew. Very little powdery mildew [Podospheara macularis Braun and Takamatus] has been observed in the field, however, numerous lesions formed on SCARLET in a greenhouse. Plants continued to grow vigorously in spite of the powdery mildew infection thus SCARLET is considered tolerant to this pathogen. Powdery mildew can be controlled via readily available fungicides. SCARLET's susceptibility to virus infections is unknown. Severe infestations of two-spotted spider mites (Tetranychus urticae Koch) have been observed in plants growing next to SCARLET in the field, however, very few mites were observed on SCARLET. Thus, SCARLET may possess resistance to the two-spotted spider mite. Damson hop aphid (Phorodon humuli Schrank) infestations have not been observed on SCARLET or neighboring plants so resistance to this pest is currently unknown. SCARLET should provide the U.S. ornamentals nursery industry with a more vigorous alternative to Blue Northern Brewer for commercial use.