Narrative
The Agricultural Research Service, USDA, announces the release of `BitterGold?, a new ?super-alpha? bittering-type hop (Humulus lupulus L.) cultivar. The primary advantages of BitterGold are its high concentration of alpha acids combined with high yield, and good storage capabilities. BitterGold originated from a 1973 cross made at Corvallis, OR, between USDA female diploid (2n=2X=20) accession 21055 and USDA male diploid accession 21110M. Female parent 21055 arose from a cross between the variety `Comet? (USDA 62013) and male accession USDA 6616-35M [an offspring from the cross, `Brewers Gold? x (`Fuggle? x Colorado 2-1)]. Male parent 21110M arose from a cross between the variety `Bullion? and a male seedling (USDA 64035M) obtained from Dr. Zattler of Germany. Based upon the abovementioned breeding pedigree, the genetic composition of BitterGold is 1/4th Bullion, 1/4th Comet, 1/4th 64035M [German aroma x OP (open pollination)], 1/8th Brewers Gold, 1/16th Fuggle, and 1/16th Wild Colorado Selection 2-1 parentage. BitterGold was originally known as cross seedling, 7313-083, which was notable for its high alpha acid levels coupled with high yields. The permanent USDA accession number, 21257, was assigned in 1980. From 1974 to 1995 this accession (BitterGold) has been sequentially planted in four different nursery locations (three near Corvallis, OR and one near Prosser, WA). Data were obtained for 11 out of the 21 growing years. In each case BitterGold has expressed alpha acid levels in excess of `Nugget? or `Galena? while maintaining good yields. Nursery plot tests in Oregon indicate a yield potential ranging from 1086 to 2486 kilograms per hectare with an average yield of 1795 kilograms per hectare. Nursery plot tests in Washington suggest even higher yield potential (maximum yield of 3091 kilograms per hectare). No special precautions were required for pruning or training although normal cultural practices used against downy mildew and powdery mildew are recommended. BitterGold matures moderately early (Aug 23 to Sept 17 in Oregon) and as such is slightly earlier than Nugget. Cones are large, tapered and compact with little shattering. Dry weights on cone samples ranged from 250 to 350 milligrams per cone. Storage stability is similar to `Centennial?, better than `Chinook? or `Eroica?, but not as good as `Nugget? or `Galena?. Chemical analyses of BitterGold suggest primary use of this variety will be extraction. Alpha acid levels range from 15.44 to 18.84 percent with an average content of 16.54 percent. Beta acid levels were less variable, but ranged from 6.13 to 8.01 with an average of 6.82 percent. Cohumulone content ranged from 36 to 41 percent (average = 35.2 percent) while the oil content in the samples ranged from 0.81 to 3.92 milliliters (average = 2.53 milliliters). Storage stability, as measured by per cent alpha acids remaining after 6 months storage at ambient (20O Celcius) temperature, ranged from 33.3 to 75 percent with an average of 56.5 percent. Average oil content during the 11 years of analyses was 68.2 percent myrcene, 8.4 percent caryophyllene, 1.2 percent farnesene, and 7.5 percent humulene. No systemic infections of downy mildew (Psuedoperonospora humuli Miy. et. Tak., G.W. Wilson) have been observed in BitterGold in any of the nursery plots. Only one instance of minor leaf infection was observed with an additional instance of slight cone infection. These cases were easily controlled with fungicides currently registered for use on hop in the United States. There is no information on the resistance of BitterGold to powdery mildew (Sphaerotheca humuli L.). No cases of verticillium wilt (incited by various Verticillium species) were observed in nursery plots. Nevertheless, growers are cautioned against growing BitterGold in known verticillium-infected fields or locations with powdery mildew until reaction to these diseases can be ascertained.