The Amarillo hop was discovered growing in a Virgil Gamache Farms Inc. (VGF) Liberty hop field. It looked more yellow-green and smelled more of grapefruit than the other hops. Visually, inside the cone was a brilliant yellow, lupulin color, Amarillo is the Spanish word for yellow, thus the name. Amarillo, Amarillo Gold and VGXP01 (the patented name) are the same and they join other new breeds of hops in the world which are used in American beers. There is no such thing as too much hops!
Amarillo’s cone is small and compact. It was called a supercharged Cascade, which was also said about Centennial. Amarillo’s oils compare to Horizon hops in all essential oils, especially the Myrcene percentage, which rank #1 and #2 of all hops. The Myrcene is that grapefruit/orange taste often referred to in beer descriptions. Horizon also matches Amarillo with very low Humulene, Caryophyllene and Farnesene oils, yet surprisingly, they are not listed as substitutes for each other.
When a cultivar hop is cross-pollinated by other hops, the cones produce seeds and a “chance seedling” is born. Fuggles is another example of a chance seedling. These were discovered by Richard Fuggle in Kent County, UK in 1861. The other methods of hop breeding are genetic modification, Polyploidy breeding and grafting which are explained below.
Genetic modification: USDA hop scientists are working to leverage the completely sequenced hop genome to combine a high yield, dual purpose, high oil, disease resistant hop with good stability into one new hop germplasm (collection of genetic resources). By introducing new genes into a hop chromosome, a cultigen (cultivated and genetically modified) is made. This is distinct from a cultivar (cultivated and variety). For most plants, the cultigen is considered a cultivar once patented.
Polyploidy breeding: Colchicine is a medicine derived from the plant Colchicum, which has been used to treat swelling since 1500 BC. The plant was brought to America by Benjamin Franklin who used it to treat his gout. A Colchicine cream is smeared on a growing shoot of a plant, resulting in doubling of the chromosomes. This genetically manipulates the plants to be better. Liberty, Mount Hood, Ultra, and Crystal hops were colchicine induced crosses between Hallertau Mittelfrueh and other hops.
Grafting: Hops use different methods, from the woody root below the ground to the scion above the ground.
Amarillo is a trademarked proprietary hop (about 30% of the hops grown in the US are proprietary hops); VGF has patented rights to grow and license others to grow Amarillo. Amarillo rhizomes are not available to hop growers without license. I cannot find disclosure of Amarillo’s yearly harvest but Hop Union reported the 2012 Amarillo crop was lower than expected, and this year’s crop has already been rationed. Hopefully, this helps explain the questions often asked in homebrew stores, “Why are Amarillo hops unavailable?” and “Where can I get Amarillo rhizomes?”