The Case for Public Varieties: Comet

Hop breeding in the United States started in 1931 with a program that is now operated by the USDA Agricultural Research Service (USDA-ARS), and now housed at Oregon State University and Washington State University. Their goal is to breed hop cultivars that are resistant to disease and pests and that exhibit high value to brewers (sought after flavor and aroma). In addition, public hop development, as it has no attached private intellectual property controls attached, ensures that all growers have access to new hop varieties. Today, there are also a number of hop varieties developed by private organizations.

Hop varieties have always come in and out of favor with brewers and growers, and it’s interesting to consider why some public hops have survived while others have been relegated to the vaults. Is it the persistence of a particular beer style, or new thoughts on how a long-standing hop can be used? With that question in mind, we thought it would be worthwhile to revisit some public hop varieties, their history, and perhaps suggest why they are surviving in the current culture. In this series, we will take a look at a few public cultivars and try to answer these questions.

Comet

Breeding and Development

Comet was released in 1974 by the USDA team of Chuck Zimmerman, Sam Likens, Al Haunold, Chester “Jack” Horner, and Don Roberts. It can rightfully be considered the first American high alpha hop cultivar. Previously available high alpha varieties at the time were Bullion and Brewer’s Gold, sister selections bred at Wye College in England. Those varieties, however, were not particularly well-suited for the Yakima Valley of Washington, where a majority of U.S. hops were being grown. Comet was cross-completed in 1961 from a seedling of Sunshine, an open-pollinated variety from England and a wild male hop that was found in Logan Canyon in Northeastern Utah.

The Comet cultivar was grown at significant acreage in the late 1970’s. In 1980, 635 acres were strung, accounting for one percent of U.S. hop production. Acreage decreased rather significantly starting in 1981, following the release of new “super alpha” hops, particularly Columbus/Tomahawk. At the time, Comet’s unique Wild American aroma was considered pungent and not desirable to the larger breweries. Beer writer Stan Hieronymus reports that Comet was kept alive likely by only one hop grower in the Yakima Valley until the early 2010’s when more Northwest growers started producing the hop. (1) As with some “rediscovered” older hop cultivars, it was their unique “American” aroma qualities that sparked renewed interest in the variety by brewers and growers. According to the National Agricultural Statistics Service, there were 331 acres of Comet strung in the Northwest for harvest in 2019 – in Washington 244 acres (0.4%) and Idaho 87 acres (1%). 

Agronomics

As with any hop variety, growers find Comet has its challenges and advantages in the field and picker. It is a fairly vigorous variety and grows well in a range of soil types and has decent resistance to most common pests and diseases, including mites, aphids, and mildew. On the string, Comet is unique with its golden-green leaves in early spring, with the leaves turning greener through the season. Comet’s late picking window is attractive to growers as there’s pressure on the mid-picking window with many of today’s hops.

As for challenges, yield for Comet can be variable with a wide range from 1,200 to 2,400 pounds per acre. Over-vigor (too much vegetative growth with lesser cone production) is best controlled with lower watering regimes and lighter nitrogen applications. It is also notorious among growers as being difficult to harvest. The cones have been called “raggy” particularly if they are left to harvest late and are difficult to remove from the vine. The vines themselves are particularly “rubbery” and are known to clog picking equipment, with the cones being a challenge to clean sufficiently. Often Comet is limited strictly to two bines per string to allow better cone production and in hopes of easing picking.

Brewing Qualities

Comet was originally developed as a Northwest-viable high alpha variety but loss favor to super alpha hops about a decade after its release. As craft beer has grown and tastes have changed, we have seen an increase in interest in this hop from brewers. What was previously called a “wild, American-character” and deemed offensive by large commercial brewers in the 1970’s is now just the type of unique hop attributes modern brewers seek out. Comet’s flavor profile leans towards citrus with strong notes of grapefruit. It’s been adopted by some brewers as a “little-sister” to some of the heavy citrus, proprietary varieties so popular today. Subtle grassy-notes and hints of bitter dankness have moved Comet into recipes for both West and East Coast IPAs. Brewers have also reported having success with the variety in beers like Saison and Kviek – styles that were not considered as a likely home for Comet when it was being developed in the 1960s and 70s.

The alpha acid content is on the higher end which would have been considered a high-alpha variety at the time of its release. Today, it would be categorized as dual-purpose, though its usefulness as a bittering hop has been negated by more modern, super alpha cultivars. Co-H is certainly on the high side. Historically, though debatable given today’s research, this would have suggested Comet would contribute a harsher bitterness to a beer. Compared to Cascade (33-40% Co-H) and Simcoe (15-20%), we can see Co-Humulone in Comet is definitely high. While this may have been a consideration when Comet was released as a potential bittering hop, it’s less of a concern today as brewers are using it more as flavor and aroma hop. In terms of total oil, Comet is about average and in-line with a number of the US hops of the time. Myrcene levels are on the higher side for earlier US cultivars and hops used at the time, but certainly not at the levels we typically see in hops of today, like Cascade or Centennial. Humulene levels, on the other hand, are relatively low as are Caryophyllene. Comet also has a lower Geraniol percentage than say a Centennial (1.2 – 1.8%) but is right in there with Pinene and Linalool percentages.

In these days where it seems much of the focus is on proprietary hop varieties, Comet is a great example of an existing public variety that has value with modern brewer and consumer tastes. The challenges growing and picking Comet may relegate it to always being a smaller acreage variety.

In increasingly competitive beer and hop industries, Comet can be seen as a success story. Privately bred, marketed, and controlled proprietary hops have taken the lead in acreage and brewer mindshare. As brewery owners are looking for ways to create beers that stand out from the crowd, Comet has maintained a toehold in Pacific Northwest hop acreage as an “old-school” public variety that stretches a brewer’s creativity, works well in a range of beer styles and provides the advantages of using public bred hop cultivars.

(1)   https://appellationbeer.com/blog/more-citra-more-mosaic-more-comet-wait-more-comet/